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Gutiérrez-Lara EJ, Sánchez-López A, Murbartián J, Acosta-Cota SJ, Centurión D. Effect of chronic administration of 17β-estradiol on the vasopressor responses induced by the sympathetic nervous system in insulin resistance rats. Steroids 2022; 188:109132. [PMID: 36273542 DOI: 10.1016/j.steroids.2022.109132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Revised: 09/14/2022] [Accepted: 10/14/2022] [Indexed: 11/05/2022]
Abstract
Several studies have demonstrated that the underlying mechanism of insulin resistance (IR) is linked with developing diseases like diabetes mellitus, hypertension, metabolic syndrome, and polycystic ovary syndrome. In turn, the dysfunction of female gonadal hormones (especially 17β-estradiol) may be related to the development of IR complications since different studies have shown that 17β-estradiol has a cardioprotector and vasorelaxant effect. This study aimed was to determine the effect of the 17β-estradiol administration in insulin-resistant rats and its effects on cardiovascular responses in pithed rats. Thus, the vasopressor responses are induced by sympathetic stimulation or i.v. bolus injections of noradrenaline (α1/2), methoxamine (α1), and UK 14,304 (α2) adrenergic agonist were determined in female pithed rats with fructose-induced insulin resistance or control rats treated with: 1) 17β-estradiol or 2) its vehicle (oil) for 5 weeks. Thus, 17β-estradiol decreased heart rate, prevented the increase of blood pressure induced by ovariectomy, but with the opposite effect on sham-operated rats; and decreased vasopressor responses induced by i.v. bolus injections of noradrenaline on sham-operated (control and fructose group) and ovariectomized (control) rats, and those induced by i.v. bolus injections of methoxamine (α1 adrenergic agonist). Overall, these results suggest 17β-estradiol has a cardioprotective effect, and its effect on vasopressor responses could be mediated mainly by the α1 adrenergic receptor. In contrast, IR with ovariectomy 17β-estradiol decreases or loses its cardioprotector effect, this could suggest a possible link between the adrenergic receptors and the insulin pathway.
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Affiliation(s)
- Erika J Gutiérrez-Lara
- Departamento de Farmacobiología, Cinvestav Unidad Coapa, Czda. de los Tenorios 235, Col. Granjas-Coapa, Deleg. Tlalpan, C.P. 14330 México City, México
| | - Araceli Sánchez-López
- Departamento de Farmacobiología, Cinvestav Unidad Coapa, Czda. de los Tenorios 235, Col. Granjas-Coapa, Deleg. Tlalpan, C.P. 14330 México City, México
| | - Janet Murbartián
- Departamento de Farmacobiología, Cinvestav Unidad Coapa, Czda. de los Tenorios 235, Col. Granjas-Coapa, Deleg. Tlalpan, C.P. 14330 México City, México
| | - Selene J Acosta-Cota
- Departamento de Ciencias de la Salud, Universidad Autónoma de Occidente, Blv. Lola Beltrán y Blv. Rolando Arjona. S/N, Col. 4 de marzo, C.P. 80020 Culiacán, Sinaloa, México
| | - David Centurión
- Departamento de Farmacobiología, Cinvestav Unidad Coapa, Czda. de los Tenorios 235, Col. Granjas-Coapa, Deleg. Tlalpan, C.P. 14330 México City, México.
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Gaynullina DK, Kudryashova TV, Vorotnikov AV, Schubert R, Tarasova OS. MAPKs Are Highly Abundant but Do Not Contribute to α 1-Adrenergic Contraction of Rat Saphenous Arteries in the Early Postnatal Period. Int J Mol Sci 2021; 22:ijms22116037. [PMID: 34204888 PMCID: PMC8199737 DOI: 10.3390/ijms22116037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 05/28/2021] [Accepted: 06/01/2021] [Indexed: 12/03/2022] Open
Abstract
Previously, the abundance of p42/44 and p38 MAPK proteins had been shown to be higher in arteries of 1- to 2-week-old compared to 2- to 3-month-old rats. However, the role of MAPKs in vascular tone regulation in early ontogenesis remains largely unexplored. We tested the hypothesis that the contribution of p42/44 and p38 MAPKs to the contraction of peripheral arteries is higher in the early postnatal period compared to adulthood. Saphenous arteries of 1- to 2-week-old and 2- to 3-month-old rats were studied using wire myography and western blotting. The α1-adrenoceptor agonist methoxamine did not increase the phosphorylation level of p38 MAPK in either 1- to 2-week-old or 2- to 3-month-old rats. Accordingly, inhibition of p38 MAPK did not affect arterial contraction to methoxamine in either age group. Methoxamine increased the phosphorylation level of p42/44 MAPKs in arteries of 2- to 3-month-old and of p44 MAPK in 1- to 2-week-old rats. Inhibition of p42/44 MAPKs reduced methoxamine-induced contractions in arteries of 2- to 3-month-old, but not 1- to 2-week-old rats. Thus, despite a high abundance in arterial tissue, p38 and p42/44 MAPKs do not regulate contraction of the saphenous artery in the early postnatal period. However, p42/44 MAPK activity contributes to arterial contractions in adult rats.
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Affiliation(s)
- Dina K. Gaynullina
- Department of Human and Animal Physiology, Faculty of Biology, M.V. Lomonosov Moscow State University, 119234 Moscow, Russia;
- Department of Physiology, Russian National Research Medical University, 117513 Moscow, Russia
- Correspondence:
| | - Tatiana V. Kudryashova
- Department of Internal Medicine, Division of Pulmonary, Critical Care and Sleep Medicine, University of California Davis, Davis, CA 95616, USA;
| | - Alexander V. Vorotnikov
- National Medical Research Center of Cardiology, Institute of Experimental Cardiology, 121552 Moscow, Russia;
| | - Rudolf Schubert
- Physiology, Institute of Theoretical Medicine, Medical Faculty, University of Augsburg, 86159 Augsburg, Germany;
| | - Olga S. Tarasova
- Department of Human and Animal Physiology, Faculty of Biology, M.V. Lomonosov Moscow State University, 119234 Moscow, Russia;
- Laboratory of Exercise Physiology, State Research Center of the Russian Federation-Institute for Biomedical Problems, Russian Academy of Sciences, 123007 Moscow, Russia
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Tamalunas A, Sauckel C, Ciotkowska A, Rutz B, Wang R, Huang R, Li B, Stief CG, Gratzke C, Hennenberg M. Inhibition of human prostate stromal cell growth and smooth muscle contraction by thalidomide: A novel remedy in LUTS? Prostate 2021; 81:377-389. [PMID: 33687083 DOI: 10.1002/pros.24114] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 02/19/2021] [Indexed: 01/08/2023]
Abstract
BACKGROUND Medical treatment in benign prostatic hyperplasia targets prostate size to prevent disease progression, complications, and surgery, and prostate smooth muscle tone for rapid relief of lower urinary tract symptoms. Combination therapies are still required to target both at once. However, current medications are insufficient, due to an unfavorable balance between side effects and efficacy. The limited efficacy of α1 -blockers may be due to nonadrenergic mediators like endothelin-1 and thromboxane A2 (TXA2 ), which keep up prostate smooth muscle contraction even in the presence of α1 -blockers. Consequently, future options with higher efficacy need to target α1 -adrenergic and nonadrenergic contractions as well as stromal cell growth at once. Thalidomide has been approved as an oral medication for various diseases, including the treatment of prostate cancer. Therefore, we investigated the effect of thalidomide on cellular functions of prostate stromal cells and human prostate smooth muscle contraction. METHODS Cytoskeletal organization was visualized by phalloidin staining, cell growth was assessed by 5-ethynyl-2'-deoxyuridine assay, cell viability by cell counting kit-8, and apoptosis and cell death by flow cytometry in cultured prostate stromal cells (WPMY-1). Contractions of human prostate tissues from radical prostatectomy were studied in an organ bath, where they were induced by the α1 -adrenoceptor agonists methoxamine, noradrenaline, phenylephrine, and the nonadrenergic agonists endothelin-1, TXA2 analog U46619, or electric field stimulation (EFS). RESULTS Thalidomide significantly reduced the proliferation of WPMY-1 cells, which was time- and concentration-dependent (10-300 µM). In parallel, organization of actin filaments collapsed after treatment with thalidomide. Thalidomide (30-100 µM) inhibited noradrenaline-, phenylephrine-, and methoxamine-induced contractions, as well as nonadrenergic contractions induced by endothelin-1 and U46619, and neurogenic contractions induced by EFS. No reduction in viability and no increases in apoptosis or in cell death were observed in WPMY-1 cells. CONCLUSIONS Thalidomide impairs the growth of human prostate stromal cells, without showing a decrease in cell viability. In parallel, thalidomide inhibits adrenergic, neurogenic, and nonadrenergic contractions. This may be explained by a breakdown of the actin cytoskeleton. In vivo, urodynamic effects of thalidomide appear possible and may even exceed those of α1 -blockers or combination therapies.
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Affiliation(s)
| | - Cora Sauckel
- Department of Urology, University Hospital, LMU Munich, Munich, Germany
| | - Anna Ciotkowska
- Department of Urology, University Hospital, LMU Munich, Munich, Germany
| | - Beata Rutz
- Department of Urology, University Hospital, LMU Munich, Munich, Germany
| | - Ruixiao Wang
- Department of Urology, University Hospital, LMU Munich, Munich, Germany
| | - Ru Huang
- Department of Urology, University Hospital, LMU Munich, Munich, Germany
| | - Bingsheng Li
- Department of Urology, University Hospital, LMU Munich, Munich, Germany
| | - Christian G Stief
- Department of Urology, University Hospital, LMU Munich, Munich, Germany
| | | | - Martin Hennenberg
- Department of Urology, University Hospital, LMU Munich, Munich, Germany
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de-Los-Santos-Cocotle G, Martínez-Morales JC, Romero-Ávila MT, Reyes-Cruz G, García-Sáinz JA. Effects of agonists and phorbol esters on α 1A-adrenergic receptor-Rab protein interactions. Eur J Pharmacol 2020; 885:173423. [PMID: 32750368 DOI: 10.1016/j.ejphar.2020.173423] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 07/21/2020] [Accepted: 07/25/2020] [Indexed: 11/29/2022]
Abstract
In a cell line, stably expressing α1A-adrenoceptors fused to the mCherry red fluorescent protein, noradrenaline, methoxamine, and oxymetazoline induced concentration-dependent increases in intracellular calcium. All of these agents increase α1A-adrenoceptor phosphorylation and internalization. Transient co-expression of these receptors with Rab proteins tagged with the enhanced Green Fluorescent Protein was employed to estimate α1A-adrenoceptor-Rab interaction using Förster Resonance Energy Transfer. Noradrenaline and methoxamine increased α1A-adrenoceptor interaction with Rab5 and Rab7 but did not modify it with Rab9. Oxymetazoline induced adrenoceptor interaction with Rab5 and Rab9 and only an insignificant increase in Rab7 signal. Phorbol myristate acetate increased α1A-adrenoceptor interaction with Rab5 and Rab9 but did not modify it with Rab7. The agonists and the active phorbol ester, all of which induce receptor phosphorylation and internalization, favor receptor interaction with Rab5, i.e., association with early endosomes. Cell stimulation with phorbol myristate acetate induced the α1A-adrenoceptors to interact with the late endosomal marker, Rab9, suggesting that the receptors are directed to slow recycling endosomes once they have transited to the Trans-Golgi network to be retrieved to the plasma membrane. The agonists noradrenaline and methoxamine likely induce a faster recycling and might direct some of the adrenoceptors toward degradation and/or very slow recycling to the plasma membrane. Oxymetazoline produced a mixed pattern of interaction with the Rab proteins. These data indicate that α1A-adrenoceptor agonists can trigger different vesicular traffic and receptor fates within the cells.
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Affiliation(s)
- Gustavo de-Los-Santos-Cocotle
- Departamento de Biología Celular y del Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Juan Carlos Martínez-Morales
- Departamento de Biología Celular y del Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - M Teresa Romero-Ávila
- Departamento de Biología Celular y del Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Guadalupe Reyes-Cruz
- Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional-CINVESTAV, Av. Instituto Politécnico Nacional 2508; Col, San Pedro Zacatenco, Mexico City, Mexico
| | - J Adolfo García-Sáinz
- Departamento de Biología Celular y del Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico.
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Wang HW, Cheng LH, Lee FP. Efficacy of vardenafil in human nasal mucosa. Am J Otolaryngol 2020; 41:102561. [PMID: 32504853 DOI: 10.1016/j.amjoto.2020.102561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 05/23/2020] [Indexed: 11/29/2022]
Abstract
OBJECTIVE Levitra, a phosphodiesterase-5 (PDE5) inhibitor, is the trade name of vardenafil. It is applied to treatment of erectile dysfunction. PDE5 inhibitors dilate the penile blood vessels and cause prolonged erections. However, the effects of Levitra on human nasal mucosa are not yet fully explored. MATERIALS AND METHODS We examined the effectiveness of Levitra on human nasal mucosa directly in vitro by testing: 1) effect on human nasal mucosa resting tension; 2) effect on contraction caused by 10-6 M methoxamine as a sympathetic mimetic; 3) effect of the drugs on electrically induced human nasal mucosa contractions. RESULTS The results showed that addition of methoxamine to the incubation medium caused the nasal mucosa to contract in a dose-dependent manner. Addition of Levitra at doses of 10-4 M elicited a significant relaxation response to 10-6 M methoxamine-induced mucosa strip contraction. Levitra could not inhibit electrical field stimulation-induced spike contraction and had a minimal effect on the basal tension of nasal mucosa as the concentration increased. CONCLUSION This study indicated that high concentrations of Levitra had a significant spasmolytic effect by antagonizing α-adrenoceptors. Moreover, nasal obstruction might not be relieved in patients suffering from erectile dysfunction and stuffy noses who were concomitant using α-adrenergic agonist and Levitra.
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Affiliation(s)
- Hsing-Won Wang
- The Graduate Institute of Clinical Medicine and Department of Otolaryngology, College of Medicine, Taipei Medical University-Shuang Ho Hospital, Taipei, Taiwan, Republic of China; Department of Otolaryngology-Head and Neck Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China.
| | - Li-Hsiang Cheng
- Department of Otolaryngology-Head and Neck Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China
| | - Fei-Peng Lee
- The Graduate Institute of Clinical Medicine and Department of Otolaryngology, College of Medicine, Taipei Medical University-Shuang Ho Hospital, Taipei, Taiwan, Republic of China.
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Wang HW, Lee JC, Wu PC, Chu YH, Lin YY, Cheng LH. Effects of montelukast on human nasal mucosa. Eur Arch Otorhinolaryngol 2019; 276:761-765. [PMID: 30604060 DOI: 10.1007/s00405-018-05274-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Accepted: 12/26/2018] [Indexed: 12/11/2022]
Abstract
OBJECTIVE Montelukast is a selective and orally active leukotriene D4 receptor antagonist often used in treating asthma and allergic rhinitis. Montelukast nasal spray was developed to avoid systemic adverse effects of the drug in vitro. However, the effects of montelukast on human nasal mucosa are not yet fully explored and potential nasal vascular side effects of the drug merit further exploration. First, the effects of montelukast on vasocontractile responses generated by smooth muscles in the vascular structures of human nasal mucosa were investigated directly in vitro. METHODS This study examined the effects of montelukast on human nasal mucosa in terms of mucosa resting tension, vasoconstriction caused by 10- 6 M methoxamine as a sympathetic mimetic, and electrically induced vasoconstrictions. RESULTS The results indicated that addition of methoxamine to the incubation medium caused the nasal mucosa to vasocontract in a dose-dependent manner. Addition of montelukast at doses of 10- 5 M or above elicited a significant vasodilation response to 10- 6 M methoxamine-induced vasoconstriction. Montelukast could not inhibit electrical field stimulation-induced spike vasoconstriction. Moreover, increase in concentration of montelukast had minimal effect on basal tension of nasal mucosa. CONCLUSIONS The study indicated significant vasodilation on human nasal mucosa under high concentrations of montelukast with a probable α-adrenoceptor antagonism. Hence, the nasal activity of α-adrenergic agonist nasal spray for nasal obstruction may be reduced in those using concomitant (oral or local spray) montelukast.
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Affiliation(s)
- Hsing-Won Wang
- Department of Otolaryngology-Head and Neck Surgery, Tri-Service General Hospital, National Defense Medical Center, 325, Cheng-Kung Road Section 2, Taipei, 114, Taiwan, ROC
- Graduate Institute of Clinical Medicine and Department of Otolaryngology, Taipei Medical University-Shuang Ho Hospital, New Taipei City, Taiwan, ROC
| | - Jih-Chin Lee
- Department of Otolaryngology-Head and Neck Surgery, Tri-Service General Hospital, National Defense Medical Center, 325, Cheng-Kung Road Section 2, Taipei, 114, Taiwan, ROC
| | - Pei-Chuan Wu
- Department of Psychiatry, Far Eastern Memorial Hospital, New Taipei City, Taiwan, ROC
| | - Yueng-Hsiang Chu
- Department of Otolaryngology-Head and Neck Surgery, Tri-Service General Hospital, National Defense Medical Center, 325, Cheng-Kung Road Section 2, Taipei, 114, Taiwan, ROC
| | - Yuan-Yung Lin
- Department of Otolaryngology-Head and Neck Surgery, Tri-Service General Hospital, National Defense Medical Center, 325, Cheng-Kung Road Section 2, Taipei, 114, Taiwan, ROC
| | - Li-Hsiang Cheng
- Department of Otolaryngology-Head and Neck Surgery, Tri-Service General Hospital, National Defense Medical Center, 325, Cheng-Kung Road Section 2, Taipei, 114, Taiwan, ROC.
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Zefirov TL, Khabibrakhmanov II, Ziyatdinova NI, Zefirov AL. Peculiar Aspects in Influence of α 1-Adrenoceptor Stimulation on Isolated Rat Heart. Bull Exp Biol Med 2016; 162:4-6. [PMID: 27878488 DOI: 10.1007/s10517-016-3530-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Indexed: 11/26/2022]
Abstract
The study examined the effect of α1-adrenoceptor stimulation with methoxamine on chronotropic function of isolated heart perfused ex vivo according to Langendorff and cardiac chronotropy in vivo. Stimulation of α1-adrenoceptors in isolated heart induced gradually developing bradycardia, which progressed during several minutes. Similar stimulation in vivo produced a short-term bradycardia probably terminated by the compensatory influences in the whole organism. Comparison of the data obtained in both experimental paradigms during α1-adrenoceptor stimulation revealed unidirectional changes in cardiac chronotropy characterized with time-related peculiarities.
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Affiliation(s)
- T L Zefirov
- Department of Human Health Protection, Kazan (Volga Region) Federal University, Kazan, the Republic of Tatarstan, Russia.
| | - I I Khabibrakhmanov
- Department of Human Health Protection, Kazan (Volga Region) Federal University, Kazan, the Republic of Tatarstan, Russia
| | - N I Ziyatdinova
- Department of Human Health Protection, Kazan (Volga Region) Federal University, Kazan, the Republic of Tatarstan, Russia
| | - A L Zefirov
- Department of Normal Physiology, Kazan Federal Medical University, Kazan, the Republic of Tatarstan, Russia
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Moeller M, Thonig A, Pohl S, Ripoll C, Zipprich A. Hepatic arterial vasodilation is independent of portal hypertension in early stages of cirrhosis. PLoS One 2015; 10:e0121229. [PMID: 25793622 PMCID: PMC4368541 DOI: 10.1371/journal.pone.0121229] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 01/29/2015] [Indexed: 12/17/2022] Open
Abstract
Introduction The compensatory increase in hepatic arterial flow with a decrease in portal venous flow is known as the hepatic arterial buffer response. In cirrhosis with elevated portal pressure, the vascular resistance of the hepatic artery is decreased. Whether this lower resistance of the hepatic artery is a consequence of portal hypertension or not remains unknown. Study Aim The aim of the study was to investigate the hepatic arterial resistance and response to vasoconstriction in cirrhosis without portal hypertension (normal portal resistance). Methods Cirrhosis was induced by CCl4-inhalation for 8 weeks (8W, normal portal resistance) and for 12–14 weeks (12W, elevated portal resistance). Bivascular liver perfusion was performed at 8W or 12W and dose response curves of methoxamine were obtained in the presence or absence of LNMMA (nitric oxide synthase blocker). Vascular resistances of the hepatic artery (HAR), portal vein (PVR) and sinusoids (SVR) were measured. Western Blot (WB) and Immunohistochemistry (IHC) were done to measure eNOS and HIF 1a expression. Results HAR in both groups of cirrhotic animals (8W and 12W) were lower compared to controls. Dose response curves to methoxamine revealed lower HAR in both cirrhotic models (8W and 12W) regardless the magnitude of portal resistance. LNMMA corrected the dose response curves in cirrhosis (8W and 12W) to control. WB and IHC show increased protein expression of eNOS and HIF1a in 8W and 12W. Conclusion Hepatic arterial resistance is decreased in cirrhosis independent of portal resistance. Vasodilation of the hepatic artery in cirrhosis seems to be influenced by hypoxia rather than increase in portal resistance. Nitric oxide is the main vasodilator.
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Affiliation(s)
- Miriam Moeller
- First Department of Internal Medicine, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Antje Thonig
- First Department of Internal Medicine, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Sabine Pohl
- First Department of Internal Medicine, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Cristina Ripoll
- First Department of Internal Medicine, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Alexander Zipprich
- First Department of Internal Medicine, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
- * E-mail:
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Acosta-Cota SJ, Sánchez-López A, Molina-Muñoz T, Gómez-Viquez NL, Centurión D. Evidence that chronic administration of 17β-oestradiol decreases the vasopressor responses to adrenergic system stimulation in streptozotocin-diabetic female rats. Steroids 2014; 83:1-9. [PMID: 24513052 DOI: 10.1016/j.steroids.2014.01.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 01/10/2014] [Accepted: 01/22/2014] [Indexed: 01/02/2023]
Abstract
In vitro studies have indicated that 17β-oestradiol exerts beneficial effects on the cardiovascular system by activating the nitric oxide pathway. However, these effects have not been demonstrated in vivo in the systemic vasculature of rats made diabetic through streptozotocin induction. Therefore, the goal of this study was to determine the effect of 17β-oestradiol on vasopressor responses induced by sympathetic stimulation or i.v. injections of noradrenaline, methoxamine and B-HT 933 in sham-operated or ovariectomised, diabetic or non-diabetic female rats. Thus, rats were ovariectomised or sham-operated for this experiment. One week later, the animals were treated with streptozotocin (60mg/kg, i.p.) or its vehicle. Two weeks later, these rats were treated daily with 17β-oestradiol (10μg/kg, s.c.) or its vehicle for five weeks. Next, under anaesthesia, the animals were pithed and prepared for blood pressure and heart rate measurements. 17β-oestradiol failed to modify the vasopressor responses to (i) sympathetic stimulation, noradrenaline, methoxamine or B-HT 933 in sham-operated non-diabetic rats; (ii) sympathetic stimulation or B-HT 933 in sham-operated diabetic rats; (iii) noradrenaline or methoxamine in ovariectomised non-diabetic rats. In contrast, 17β-oestradiol significantly decreased the vasopressor responses to (i) noradrenaline and methoxamine in sham-operated diabetic rats; (ii) sympathetic stimulation or B-HT 933 in ovariectomised non-diabetic rats; and (iii) sympathetic stimulation, noradrenaline, methoxamine or B-HT 933 in ovariectomised diabetic rats. These results suggest that chronic administration of 17β-oestradiol decreases the vasopressor responses to adrenergic system stimulation in streptozotocin-induced diabetic rats. This report describes the first in vivo study reporting this effect of 17β-oestradiol in diabetes.
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Affiliation(s)
- Selene J Acosta-Cota
- Departamento de Farmacobiología, Cinvestav-Coapa, Czda. de los Tenorios 235, Col. Granjas Coapa, Deleg. Tlalpan, C.P. 14330 México D.F., Mexico
| | - Araceli Sánchez-López
- Departamento de Farmacobiología, Cinvestav-Coapa, Czda. de los Tenorios 235, Col. Granjas Coapa, Deleg. Tlalpan, C.P. 14330 México D.F., Mexico
| | - Tzindilu Molina-Muñoz
- Departamento de Farmacobiología, Cinvestav-Coapa, Czda. de los Tenorios 235, Col. Granjas Coapa, Deleg. Tlalpan, C.P. 14330 México D.F., Mexico
| | - Norma L Gómez-Viquez
- Departamento de Farmacobiología, Cinvestav-Coapa, Czda. de los Tenorios 235, Col. Granjas Coapa, Deleg. Tlalpan, C.P. 14330 México D.F., Mexico
| | - David Centurión
- Departamento de Farmacobiología, Cinvestav-Coapa, Czda. de los Tenorios 235, Col. Granjas Coapa, Deleg. Tlalpan, C.P. 14330 México D.F., Mexico.
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Abdulla MH, Sattar MA, Abdullah NA, Johns EJ. The effect of high-fructose intake on the vasopressor response to angiotensin II and adrenergic agonists in Sprague-Dawley rats. Pak J Pharm Sci 2013; 26:727-732. [PMID: 23811449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Effect of losartan was assessed on systemic haemodynamic responses to angiotensin II (Ang II) and adrenergic agonists in the model of high-fructose-fed rat. Twenty-four Sprague-Dawley (SD) rats were fed for 8 weeks either 20% fructose solution (FFR) or tap water (C) ad libitum. FFR or C group received losartan (10mg/kg/day p.o.) for 1 week at the end of feeding period (FFR-L and L) respectively, then the vasopressor responses to Ang II, noradrenaline (NA), phenylephrine (PE) and methoxamine (ME) were determined. The responses (%) to NA, PE, ME and Ang II in FFR were lower (P<0.05) than C (FFR vs. C; 22±2 vs. 32±2, 30±3 vs. 40±3, 9±1 vs. 13±1, 10±1 vs. 17±1) respectively. L group had blunted (P<0.05) responses to NA, PE, ME and Ang II compared to C (L vs. C; 26±2 vs. 32±2, 30±3 vs. 40±3, 7±0.7 vs. 13±1, 5±0.4 vs. 17±1) respectively. FFR-L group had aggravated (P<0.05) response to NA and ME, but blunted response to Ang II compared to FFR (FFR-L vs. FFR; 39±3 vs. 22±2, 11±1 vs. 9±1, 3±0.4 vs. 10±1) respectively. Fructose intake for 8 weeks results in smaller vasopressor response to adrenergic agonists and Ang II. Data also demonstrated an important role played by Ang II in the control of systemic haemodynamics in FFR and point to its interaction with adrenergic neurotransmission.
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Affiliation(s)
- Mohammed Hadi Abdulla
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, Minden, Penang, Malaysia.
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Hernández-Guerra M, de Ganzo ZA, González-Méndez Y, Salido E, Abreu P, Moreno M, Felipe V, Abrante B, Quintero E. Chronic intermittent hypoxia aggravates intrahepatic endothelial dysfunction in cirrhotic rats. Hepatology 2013; 57:1564-74. [PMID: 23174804 DOI: 10.1002/hep.26152] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 11/01/2012] [Indexed: 12/17/2022]
Abstract
UNLABELLED Chronic intermittent hypoxia (CIH) occurs with obstructive sleep apnea syndrome (OSAS) and provokes systemic endothelial dysfunction, which is associated with oxidative stress and low nitric oxide (NO) bioavailability. Cirrhotic livers exhibit intrahepatic endothelial dysfunction, which is characterized by an impaired endothelium-dependent response to vasodilators and hyperresponse to vasoconstrictors. We hypothesized that CIH may also contribute to intrahepatic endothelial dysfunction in cirrhosis. Normal and cirrhotic rats were exposed for 14 days to repetitive cycles of CIH mimicking OSAS in humans, or caged with room air (handled controls [HC]). Hepatic endothelial function was assessed in isolated and perfused rat livers by dose-response curves to acetylcholine (ACh) and methoxamine (Mtx). In a group of cirrhotic rats, in vivo systemic and hepatic hemodynamic parameters were evaluated at baseline and after volume expansion. In addition, liver samples were obtained to assess endothelial nitric oxide synthase (eNOS), phosphorylated eNOS (p-eNOS), NO bioavailability, and nitrotyrosinated proteins as a marker of oxidative stress. Cirrhotic rats exposed to CIH exhibited an attenuated vasodilatory response to ACh and hyperresponse to Mtx compared with HC rats. During volume expansion, similar portal pressure increases were observed in CIH and HC rats, although the mean arterial pressure increase was lower after CIH. These functional responses were associated with the presence of increased hepatic oxidative stress without changes in p-eNOS after CIH exposure. In normal rats, no hemodynamic changes were found. CONCLUSION CIH exacerbates intrahepatic endothelial dysfunction in cirrhotic rats, which is associated with increased oxidative stress that may reduce NO bioavailability. Clinical studies are needed to assess whether OSAS contributes to endothelial impairment in human patients with cirrhosis.
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Tep-Areenan P, Suksamrarn S. Mechanisms of vasorelaxation to gamma-mangostin in the rat aorta. J Med Assoc Thai 2012; 95 Suppl 12:S63-S68. [PMID: 23513467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
OBJECTIVE To investigate the effects of gamma-mangostin on vascular tone and its mechanisms in the isolated rat aorta. MATERIAL AND METHOD Aortic rings from male Wistar rats were precontracted with methoxamine. Changes in tension were measured using an isometric force transducer and recorded on the MacLab recording system. Vasorelaxant effects of gamma-mangostin were studied in the presence of 300 microM N(G)-nitro L-arginine methyl ester (L-NAME), 10 microM 1H-[1,2,4] oxadiazolo-[4,3-a] quinoxalin-1-one (ODQ), 10 microM indomethacin, 60 mM KCl, 5 mM tetraethylammonium (TEA), 10 microM glibenclamide, 1 mM4-aminopyridine (4-AP) or 30 microM barium chloride (BaCl2). Moreover the effects of gamma-mangostin on contraction to CaCl2 were evaluated. RESULTS Gamma-mangostin (1-100 microM) induced a concentration-dependent vasorelaxation in rat aortic rings precontracted with methoxamine. This effect was significantly reduced after removal of the endothelium and after pretreatment of the rings with L-NAME, ODQ, high KCl solution, or TEA. However, vasorelaxant responses to gamma-mangostin were not altered by indomethacin, 4-AP, BaCl2 or glibenclamide. Moreover, contractions to CaCl2 (10 mM-30 mM) were reduced by pre-treatment with gamma-mangostin (10 and 100 microM). CONCLUSION Gamma-mangostin causes vasorelaxation which is mediated via the NO-cGMP pathway. Moreover activation of K+ channels and inhibition of extracellular Ca2+ influx from the extracellular space are largely involved in the relaxant effects of gamma-mangostin. These data suggest that gamma-mangostin may acts as an antihypertensive agent.
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Affiliation(s)
- Patcharin Tep-Areenan
- Department of Physiology, Faculty of Medicine, Srinakharinwirot University, Bangkok, Thailand.
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Nusuetrong P, Sotanaphun U, Tep-Areenan P. Effects of Phikud Navakot extract on vascular reactivity in the isolated rat aorta. J Med Assoc Thai 2012; 95 Suppl 12:S1-S7. [PMID: 23513458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The aim of the present study is to investigate the effect of standardized Phikud Navakot extract (NVKE) on aortic rings from male Sprague Dawley rats. Changes in tension were measured using an isometric force transducer and recorded on the PowerLab recording system. Vasorelaxant effect of NVKE was examined in the presence of indomethacin (10 microM), N(G)-nitro L-arginine methyl ester (L-NAME, 300 microM), methoxamine (0.1-300 microM), carbachol (1 nanoM-30 microM), or sodium nitroprusside (0.1 nanoM-10 microM). The results showed that NVKE (1-300 microg/mL) caused vasorelaxation in a concentration-dependent manner with a pEC50 value of 4.27 +/- 0.24 and R(max) of 67.7 +/- 13.9%. Pretreatment with indomethacin or L-NAME did not affect NVKE-induced vasorelaxation. However, co-incubation of indomethacin and L-NAME significantly reduced (p < 0.05) vasorelaxation to NVKE (100 microg/mL). Pre-treatment with NVKE significantly decreased (p < 0.05) endothelium-dependent relaxations to carbachol (R(max) = 52.90 +/- 14.3%), but not to sodium nitroprusside. Moreover contractions to methoxamine were unaffected after pretreatment with NVKE. The present study suggested that NVKE decreased vasorelaxation to carbachol in the rat aorta, which may exert at least against muscarinic receptors. These findings support the use of Phikud Navakot, a major ingredient of Yahom Navakot, against dizziness and fainting.
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Affiliation(s)
- Punnee Nusuetrong
- Department of Physiology, Faculty of Medicine, Srinakharinwirot University, Bangkok, Thailand.
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Greenhill LL. Cautious reassurance: cardiovascular risk in the context of stimulant use. J Am Acad Child Adolesc Psychiatry 2012; 51:132-3. [PMID: 22265358 DOI: 10.1016/j.jaac.2011.11.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Accepted: 11/23/2011] [Indexed: 11/19/2022]
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Abdulla MH, Sattar MA, Johns EJ, Abdullah NA, Khan MAH. Evidence for the role of α1A-adrenoceptor subtype in the control of renal haemodynamics in fructose-fed Sprague-Dawley rat. Eur J Nutr 2011; 50:689-97. [PMID: 21373947 DOI: 10.1007/s00394-011-0180-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2010] [Accepted: 02/17/2011] [Indexed: 12/19/2022]
Abstract
AIM To explore the hypothesis that high fructose intake results in a higher functional contribution of α1A-adrenoceptors and blunts the adrenergically and angiotensin II (Ang II)-induced renal vasoconstriction. METHODS Twelve Sprague-Dawley rats received either 20% fructose solution [FFR] or tap water [C] to drink ad libitum for 8 weeks. The renal vasoconstrictor response to noradrenaline (NA), phenylephrine (PE), methoxamine (ME) and Ang II was determined in the presence and absence of 5-methylurapidil (5-MU) (α1A-adrenoceptor antagonist) in a three-phase experiment (pre-drug, low- and high-dose 5-MU). Data, mean ± SEM were analysed by ANOVA or Student's unpaired t-test with significance at P < 0.05. RESULTS FFR exhibited insulin resistance (HOMA index), hypertension and significant increases in plasma levels of glucose and insulin. All agonists caused dose-related reductions in cortical blood perfusion that were larger in C than in FFR while the magnitudes of the responses were progressively reduced with increasing doses of 5-MU in both C and FFR. The degree of 5-MU attenuation of the renal cortical vasoconstriction due to NA, ME and Ang II was significantly greater in the FFR compared to C. CONCLUSIONS Fructose intake for 8 weeks results in smaller vascular response to adrenergic agonists and Ang II. The α1A-adrenoceptor subtype is the functional subtype that mediates renal cortical vasoconstriction in control rats, and this contribution becomes higher due to fructose feeding.
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Affiliation(s)
- Mohammed H Abdulla
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, 11800, Minden, Penang, Malaysia.
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Abdulla MH, Sattar MA, Abdullah NA, Khan AH, Anand Swarup KRL, Rathore HA, Kazi RN, Basri F, Johns EJ. Effect of renal sympathetic nerve on adrenergically and angiotensin II-induced renal vasoconstriction in normal Wistar-Kyoto rats. Ups J Med Sci 2011; 116:18-25. [PMID: 21047287 PMCID: PMC3039756 DOI: 10.3109/03009734.2010.526723] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND This study examined the effect of renal sympathetic innervation on adrenergically and angiotensin II (Ang II)-induced renal vasoconstriction in Wistar-Kyoto (WKY) rats. METHODS Forty-eight WKY rats were treated with either losartan (10 mg/kg/day p.o.) or carvedilol (5 mg/kg/day p.o.) or a combination of them (10 mg/kg/day + 5 mg/kg/day p.o.) for 7 days. On day 8, the rats were anaesthetized, and renal vasoconstrictor experiments were carried out. A group of rats was subjected to acute unilateral renal denervation during the acute study. Changes in the renal vasoconstrictor responses were determined in terms of reductions in renal blood flow caused by Ang II, noradrenaline (NA), and methoxamine (ME). RESULTS In normal animals, losartan decreased (P < 0.05) the renal vasoconstrictor response to Ang II but not to NA or ME. Carvedilol treatment, however, blunted (P < 0.05) the renal vasoconstrictor responses to Ang II and adrenergic agonists. Combination of losartan and carvedilol blunted (P < 0.05) the renal vasoconstrictor response to Ang II but augmented the responses to NA and ME (all P < 0.05). Interestingly, when denervated rats were treated with the same combination, there was a reduction (P < 0.05) in the renal vasoconstrictor responses to Ang II and adrenergic agonists. CONCLUSIONS Data suggest that the renal sympathetic nerve contributes to adrenergic agonist-mediated renal vasoconstrictions in normal rats. The data further indicate an interactive relationship between renin-angiotensin and sympathetic nervous systems in modulating adrenergically and Ang II-induced renal vasoconstriction in WKY rats.
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Affiliation(s)
- Mohammed H Abdulla
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, Minden, Penang, Malaysia.
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Kerber RE, Marcus ME, Ehrhardt J, Abboud FM. Effect of increases in afterload on the systolic thickening of acutely ischemic myocardium. An experimental echocardiographic study. Acta Med Scand Suppl 2009; 627:142-51. [PMID: 286504 DOI: 10.1111/j.0954-6820.1979.tb01097.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Nagareddy PR, McNeill JH, MacLeod KM. Chronic inhibition of inducible nitric oxide synthase ameliorates cardiovascular abnormalities in streptozotocin diabetic rats. Eur J Pharmacol 2009; 611:53-9. [PMID: 19344709 DOI: 10.1016/j.ejphar.2009.03.061] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2008] [Revised: 03/11/2009] [Accepted: 03/23/2009] [Indexed: 02/05/2023]
Abstract
Previous studies from our lab have demonstrated cardiovascular abnormalities such as depressed mean arterial blood pressure and heart rate, endothelial dysfunction and attenuated pressor responses to vasoactive agents in streptozotocin diabetic rats. We investigated whether these abnormalities are due to diabetes-associated chronic activation of inducible nitric oxide synthase (iNOS). Control and streptozotocin (60 mg/kg, iv) diabetic rats were treated with either vehicle or N6-(1-Iminoethyl)-L-lysine dihydrochloride (L-NIL, 3 mg/kg/day, p.o), a specific inhibitor of iNOS for 8 weeks. At the end of treatment, the mean arterial blood pressure and heart rate were measured in freely moving conscious rats. Further, pressor responses to bolus doses of methoxamine were determined. Endothelial nitric oxide synthase (eNOS) and iNOS expression as well as nitrotyrosine (NT) levels were assessed in the heart and superior mesenteric arteries by western blot and immunohistochemistry. Untreated diabetic rats showed depressed mean arterial blood pressure and heart rate and exhibited vascular hyporeactivity that were significantly improved by treatment with L-NIL. Further, decreased eNOS expression and increased iNOS expression and activity were associated with increased NT levels in the heart and superior mesenteric arteries of untreated diabetic rats. L-NIL treatment of diabetic rats normalized the expression of eNOS and NT levels without any effect on iNOS expression in the heart and superior mesenteric arteries. The results of our study suggest that induction of iNOS in cardiovascular tissues contributes significantly to the depressed mean arterial blood pressure, heart rate and pressor responses to vasoactive agents. Chronic inhibition of iNOS in diabetes may prove beneficial in the treatment of cardiovascular abnormalities.
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Mochalov SV, Kalenchuk VU, Gaĭnullina DK, Vorotnikov AV, Tarasova OS. [The contribution of protein kinase C and Rho-kinase to the control of the receptor-dependent artery contraction decreases with age independently of sympathetic innervation]. Biofizika 2008; 53:1102-1108. [PMID: 19137699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The age-related dynamics of the activity of signalling pathways coupled to alpha1-adrenergic receptors and their dependence on the sympathetic innervation of arterial smooth muscle have been studied. The effects of the protein kinase C inhibitor (GF109203X, 10(-6) M) and the Rho-kinase inhibitor (Y27632, 10(-5) M) on the isometric contraction of the rat saphenous artery, induced by the alpha1-adrenoceptor agonist methoxamine, were examined. It was shown that the sensitivity to methoxamine of arteries from 2-week-old rats that are partially innervated was reduced as compared to adults, but the effects of both inhibitors were more prominent. The denervation induced by the excision of sympathetic ganglia increased the arterial sensitivity to methoxamine but was not accompanied by changes in sensitivity to the inhibitors. Therefore, the postnatal development of the arterial smooth muscle is characterized by a decrease in the contribution of protein kinase C and Rho-kinase to the regulation of contraction; however, these changes do not correlate with changes in the sensitivity of arteries to methoxamine and development of sympathetic innervation.
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MESH Headings
- Adrenergic alpha-1 Receptor Agonists
- Age Factors
- Amides/pharmacology
- Animals
- Arteries/growth & development
- Arteries/innervation
- Arteries/physiology
- Ganglionectomy
- Indoles/pharmacology
- Isometric Contraction
- Maleimides/pharmacology
- Methoxamine/pharmacology
- Muscle, Skeletal/blood supply
- Muscle, Smooth, Vascular/growth & development
- Muscle, Smooth, Vascular/innervation
- Muscle, Smooth, Vascular/physiology
- Protein Kinase C/antagonists & inhibitors
- Protein Kinase C/physiology
- Pyridines/pharmacology
- Rats
- Rats, Wistar
- Receptors, Adrenergic, alpha-1/physiology
- Sympathetic Nervous System/growth & development
- Sympathetic Nervous System/physiology
- rho-Associated Kinases/antagonists & inhibitors
- rho-Associated Kinases/physiology
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Armenia A, Sattar MA, Abdullah NA, Khan MAH, Johns EJ. Functional subtypes of renal alpha1-adrenoceptor in diabetic and non-diabetic 2K1C Goldblatt renovascular hypertension. Acta Pharmacol Sin 2008; 29:564-72. [PMID: 18430364 DOI: 10.1111/j.1745-7254.2008.00788.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
AIM This study investigates the subtypes of the alpha1-adrenoceptor mediating the adrenergically-induced renal vasoconstrictor responses in streptozotocin-induced diabetic and non-diabetic 2-kidney one clip (2K1C) Goldblatt hypertensive rats. METHODS The renal blood flow responses to renal nerve stimulation, noradrenaline, phenylephrine, and methoxamine were measured in the absence and presence of nitrendipine, 5-methylurapidil, chloroethylclonidine and BMY 7378. RESULTS The renal vasoconstrictor responses were markedly attenuated by nitrendipine and 5- methylurapidil in the diabetic rats (all P< 0.05). In the non-diabetic rats, these responses were markedly attenuated by nitrendipine, 5-methylurapidil, and BMY 7378 (all P< 0.05). In both experimental groups, chloroethylclonidine markedly accentuated the renal vasoconstrictions caused by all the adrenergic stimuli (all P< 0.05). CONCLUSION These observations indicate that alpha 1A-adrenoceptor subtypes play a major role in mediating adrenergically-induced renal vasoconstriction in the diabetic 2K1C Goldblatt hypertensive rats. In the non-diabetic 2K1C Goldblatt hypertensive rats, contributions of alpha 1A and alpha 1D-adrenoceptor subtypes were proposed. Apart from post-synaptic alpha 1-adrenoceptors, both in the diabetic and non-diabetic 2K1C Goldblatt hypertensive rats, the potential involvement of presynaptic alpha 1- adrenoceptors is also suggested.
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Affiliation(s)
- A Armenia
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, Penang 11800, Malaysia
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Wilkinson JD, Kendall DA, Ralevic V. Delta 9-tetrahydrocannabinol inhibits electrically-evoked CGRP release and capsaicin-sensitive sensory neurogenic vasodilatation in the rat mesenteric arterial bed. Br J Pharmacol 2007; 152:709-16. [PMID: 17828286 PMCID: PMC2190020 DOI: 10.1038/sj.bjp.0707448] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2007] [Revised: 07/17/2007] [Accepted: 08/09/2007] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE Calcitonin gene-related peptide (CGRP) is a sensory neurotransmitter in the rat mesenteric arterial bed. Certain cannabinoids can inhibit, via CB(1) receptors, vasorelaxant responses to electrical field stimulation (EFS) of sensory nerves in the rat mesentery, but the mechanism of the inhibitory effect of the cannabinoid delta 9-tetrahydrocannabinol (THC) is unclear. This study assessed directly the effect of THC on EFS-induced release of CGRP from sensory nerves in the rat mesenteric bed and investigated the possible involvement of cannabinoid receptors and transient receptor potential (TRP) ion channels. EXPERIMENTAL APPROACH Rat mesenteric beds were perfused with physiological salt solution. Sensory nerves were stimulated electrically and perfusate levels of CGRP measured by immunoassay. The effects of THC on EFS-induced CGRP release and vasorelaxant responses to sensory nerve stimulation were investigated in the absence and presence of cannabinoid antagonists and TRP channel blockers. KEY RESULTS EFS evoked a release of CGRP and vasodilatation of the mesenteric beds. THC inhibited the electrically-evoked release of CGRP and sensory neurogenic vasorelaxation. The effect of THC was unaffected by the CB1 antagonist AM251, the CB2 antagonist AM630 or the TRPV1 receptor antagonist capsazepine, but was blocked by the TRP channel blocker ruthenium red. CONCLUSIONS AND IMPLICATIONS THC inhibits the EFS-induced release of CGRP (and subsequent vasorelaxation), from capsaicin-sensitive sensory nerves in the rat perfused mesentery. The effect of THC was not mediated by CB1, CB2 or TRPV1 receptors, but was sensitive to ruthenium red, suggesting a possible involvement of TRP ion channels.
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Affiliation(s)
- J D Wilkinson
- Centre for Integrated Systems Biology & Medicine, School of Biomedical Sciences, University of Nottingham Nottingham, UK
| | - D A Kendall
- Centre for Integrated Systems Biology & Medicine, School of Biomedical Sciences, University of Nottingham Nottingham, UK
| | - V Ralevic
- Centre for Integrated Systems Biology & Medicine, School of Biomedical Sciences, University of Nottingham Nottingham, UK
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Abstract
We have proposed a three step model for the specification of left-right in mammalian embryos. The fundamental assumption is that handedness is imparted by an asymmetrical molecule. Conversion of molecular asymmetry to the cellular level gives a property to one side of the embryo to bias an otherwise random generation of an asymmetrical gradient which can be interpreted by developing organs. Rat embryos, treated at discrete stages, show a window of sensitivity for disruption of handedness, which may reflect the time of conversion/biasing. Heat shock and several chemicals cause left-right inversion in up to 50% of embryos exposed during neural groove formation. Earlier stages are less sensitive; no treatment begun after foregut pocket formation influences asymmetry. Evidence for cellular interactions in left-right specification comes from the apparent rescue of iv/iv mutant embryos in chimeras. We are looking for molecular left-right disparity before morphological asymmetry but detect no differences in two-dimensional protein profiles. Using an indirect measure, we find a right-left gradient of tissue oxygen in embryos at the 20-30 somite stage. This may reflect asymmetrical vasculature, as we have suggested to explain drug-induced asymmetrical limb malformations.
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Affiliation(s)
- N A Brown
- MRC Experimental Embryology and Teratology Unit, St George's Hospital Medical School, London, UK
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Kamikihara SY, Mueller A, Lima V, Akinaga J, Nojimoto FD, Castilho A, Buratini J, Pupo AS. alpha1-Adrenoceptors in proximal segments of tail arteries from control and reserpinised rats. Naunyn Schmiedebergs Arch Pharmacol 2007; 376:117-26. [PMID: 17676312 DOI: 10.1007/s00210-007-0176-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2007] [Accepted: 06/28/2007] [Indexed: 10/23/2022]
Abstract
It has been recently shown that the supersensitivity of distal segments of the rat tail artery to phenylephrine after chemical sympathectomy with reserpine results from the appearance of alpha(1D)-adrenoceptors. It is known that both alpha(1A)- and alpha(1D)-adrenoceptors are involved in the contractions of proximal portions of the rat tail artery. Therefore, this study investigated whether sympathectomy with reserpine would induce supersensitivity in proximal segments of the rat tail artery, a tissue in which alpha(1D)-adrenoceptors are already functional. Proximal segments of tail arteries from reserpinised rats were three- to sixfold more sensitive to phenylephrine and methoxamine than were arteries from control rats (n = 6-2; p < 0.05). The imidazolines N-[5-(4,5-Dihydro-1H-imidazol-2-yl)-2-hydroxy-5,6,7,8-tetrahydronaphthalen-1-yl]methanesulfonamide hydrobromide (A-61603) and oxymetazoline, which activate selectively alpha(1A)-adrenoceptors, were equipotent in tail arteries from control and reserpinised rats (n = 4-2; p < 0.05), whereas buspirone, which activates selectively alpha(1D)-adrenoceptor, was approximately 4-fold more potent in tail arteries from reserpinised rats (n = 4-6; p < 0.05). Prazosin (nonselective) and 5-methylurapidil (alpha(1A)-selective), were competitive antagonists of contractions induced by phenylephrine and were equipotent in tail arteries from control and reserpinised rats (n = 4-6). The selective alpha(1D)-adrenoceptor antagonist 8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4.5]decane-7,9-dione dihydrochloride (BMY-7378) presented similar complex antagonism in tail arteries from control and reserpinised rats, with Schild slopes much lower than 1.0 (p < 0.05, n = 4-6). Semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR) revealed that mRNA encoding alpha(1A)-and alpha(1B)-adrenoceptors are similarly distributed in tail arteries from control and reserpinised rats, whereas mRNA for alpha(1D)-adrenoceptors is twice more abundant in the tail artery from reserpinised rats. In conclusion, the supersensitivity induced by reserpine is related only to alpha(1D)-adrenoceptors, even in tissues where this receptor subtype is already present and functional. Only the use of subtype-selective alpha(1)-adrenoceptor agonists detected the increased alpha(1D)-adrenoceptor component after reserpinisation, as the antagonists behaved similarly in tail arteries from control and reserpinised rats.
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MESH Headings
- Adrenergic alpha-1 Receptor Agonists
- Adrenergic alpha-1 Receptor Antagonists
- Animals
- Arteries/drug effects
- Arteries/innervation
- Arteries/metabolism
- Buspirone/pharmacology
- Gene Expression
- Imidazoles/pharmacology
- In Vitro Techniques
- Male
- Methoxamine/pharmacology
- Muscle Contraction/drug effects
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/physiology
- Oxymetazoline/pharmacology
- Phenylephrine/pharmacology
- Piperazines/pharmacology
- Prazosin/pharmacology
- RNA, Messenger/biosynthesis
- Rats
- Rats, Wistar
- Receptors, Adrenergic, alpha-1/biosynthesis
- Reserpine/pharmacology
- Reverse Transcriptase Polymerase Chain Reaction
- Sympathectomy
- Tail/blood supply
- Tetrahydronaphthalenes/pharmacology
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Affiliation(s)
- Susana Y Kamikihara
- Department of Pharmacology, Instituto de Biociências, UNESP, Botucatu, SP 18618-000, Brazil
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Khan AH, Sattar MA, Abdullah NA, Johns EJ. Influence of cisplatin-induced renal failure on the α1-adrenoceptor subtype causing vasoconstriction in the kidney of the rat. Eur J Pharmacol 2007; 569:110-8. [PMID: 17559832 DOI: 10.1016/j.ejphar.2007.04.063] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Revised: 04/17/2007] [Accepted: 04/20/2007] [Indexed: 10/23/2022]
Abstract
This study investigated whether the alpha(1)-adrenoceptor subtype(s) mediating the vasoconstrictor actions of the renal sympathetic nerves were altered in rats with cisplatin-induced renal failure. Male Wistar Kyoto rats were used and half received cisplatin (5 mg/kg i.p.) to induce renal failure and were taken for study 7 days later. The renal blood flow reductions caused by electrical renal nerve stimulation and close intra-renal administration of noradrenaline, phenylephrine and methoxamine were determined before and after amlodopine (AMP), 5-methylurapidil (MeU), chloroethylclonidine (CEC) or BMY 7378. Water intake and creatinine clearance were decreased (P<0.05) by 40-50% while fractional excretion of sodium was increased two-fold in the cisplatin treated rats. Mean arterial pressure was higher, 110+/-2 versus 102+/-3 mmHg and renal blood flow was lower, 10.7+/-0.9 versus 18.9+/-0.1 ml/min/kg in the renal failure rats (both P<0.05). AMP, MeU and BMY 7378 decreased (all P<0.05) the adrenergically induced renal vasoconstrictor responses in the renal failure groups by 30 to 50% and in normal rats by 20 to 40%. In the presence of CEC, renal nerve stimulation and noradrenaline and methoxamine induced renal vasoconstrictor responses were enhanced (all P<0.05) in the renal failure but not in the normal rats. These data showed that alpha(1A)- and alpha(1D)-adrenoceptors were the major subtypes in mediating adrenergically induced renal vasoconstriction but there was no substantial shift in subtype in renal failure. The contribution of alpha(1B)-adrenoceptor subtypes either pre- or post-synaptic appeared to be raised in the renal failure rats.
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Affiliation(s)
- Abdul H Khan
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia
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Putzke C, Wemhöner K, Sachse FB, Rinné S, Schlichthörl G, Li XT, Jaé L, Eckhardt I, Wischmeyer E, Wulf H, Preisig-Müller R, Daut J, Decher N. The acid-sensitive potassium channel TASK-1 in rat cardiac muscle. Cardiovasc Res 2007; 75:59-68. [PMID: 17389142 DOI: 10.1016/j.cardiores.2007.02.025] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2006] [Revised: 02/21/2007] [Accepted: 02/23/2007] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVE The outward current flowing through the two-pore domain acid-sensitive potassium channel TASK-1 (I(TASK)) and its inhibition via alpha1-adrenergic receptors was studied in rat ventricular cardiomyocytes. METHODS Quantitative RT-PCR experiments were carried out with mRNA from rat heart. Patch-clamp recordings were performed in isolated rat cardiomyocytes. TASK-1 and other K+ channels were expressed in Xenopus oocytes to study the pharmacological properties of a new TASK-1 channel blocker, A293. RESULTS TASK-1 channels were found to be strongly expressed in rat heart. Analysis of the sensitivity of various K+ channels to A293 in Xenopus oocytes showed that at low concentrations A293 was a selective blocker of TASK-1 channels. I(TASK) in rat cardiomyocytes was dissected by application of A293 and by extracellular acidification to pH 6.0; it had an amplitude of approximately 0.30 pA/pF at +30 mV. Application of 200 nM A293 increased action potential duration (APD(50)) by 31+/-3% at a stimulation rate of 4 Hz. The plausibility of the effects of A293 on APD50 was checked with a mathematical action potential model. Application of the alpha1-adrenergic agonist methoxamine inhibited I(TASK) in Xenopus oocytes co-injected with cRNA for TASK-1 and alpha1A-receptors. In cardiomyocytes, methoxamine inhibited an outward current with characteristics similar to I(TASK). This effect was abolished in the presence of the alpha1A-antagonist 5-methyl-urapidil. CONCLUSIONS Our results suggest that in rat cardiomyocytes I(TASK) makes a substantial contribution to the outward current flowing in the plateau range of potentials and that this current component can be inhibited via alpha1A-adrenergic receptors.
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Affiliation(s)
- Caroline Putzke
- Klinik für Anästhesiologie, Universitätsklinikum Marburg, 35033 Marburg, Germany
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Lee CH, Loureiro-Silva MR, Abraldes JG, Iwakiri Y, Haq O, Groszmann RJ. Decreased intrahepatic response to alpha(1)-adrenergic agonists in lipopolysaccharide-treated rats is located in the sinusoidal area and depends on Kupffer cell function. J Gastroenterol Hepatol 2007; 22:893-900. [PMID: 17498219 DOI: 10.1111/j.1440-1746.2007.04922.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
BACKGROUND AND AIM Livers from lipopolysaccharide-treated rats have a decreased vascular response to alpha(1)-adrenergic agonists due to an increased production of nitric oxide. Kupffer cells play a central role in the development of intrahepatic microvascular abnormalities during endotoxemia. We investigated the role of Kupffer cells in the intrahepatic vascular tone control in normal and endotoxemic rats. METHOD Twenty-four hours after pretreatment with gadolinium chloride (to eliminate/inactivate Kupffer cells) or saline, rats were treated with lipopolysaccharide or a second dose of saline. Six hours later, rats (under deep anesthesia) were submitted to liver perfusion with Krebs-Henseleit solution using a system that allowed the measurement of both perfusion and sinusoidal pressures. Dose-response curves to methoxamine (alpha(1)-adrenergic agonist) were obtained in the absence or the presence of the nitric oxide synthase inhibitor N-monomethyl-L-arginine. RESULTS Pretreatment with gadolinium did not change the intrahepatic vascular response to methoxamine in normal livers. Livers from lipopolysaccharide-treated rats showed a decreased sinusoidal vascular response to methoxamine and a 10-fold increase in nitric oxide production during liver perfusion. Either pretreatment with gadolinium or the presence of N-monomethyl-L-arginine in the perfusate restored the response to methoxamine and decreased the nitric oxide overproduction by more than 50%. CONCLUSIONS Kupffer cells neither mediate nor modulate the intrahepatic vascular response to alpha(1)-adrenergic agonists in normal livers. Reduction in intrahepatic vascular response to alpha(1)-adrenergic agonists in livers from lipopolysaccharide-treated rats is located in the sinusoidal area and depends on Kupffer cell function.
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Affiliation(s)
- Chang-Hyeong Lee
- Hepatic Hemodynamic Laboratory, VA Medical Center, West Haven, Connecticut 06516, USA
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Zerpa H, Berhane Y, Elliott J, Bailey SR. Cooling augments vasoconstriction mediated by 5-HT1 and alpha2-adrenoceptors in the isolated equine digital vein: involvement of Rho kinase. Eur J Pharmacol 2007; 569:212-21. [PMID: 17560569 DOI: 10.1016/j.ejphar.2007.04.057] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2006] [Revised: 04/24/2007] [Accepted: 04/25/2007] [Indexed: 11/26/2022]
Abstract
The vasculature of the equine digit fulfils an important role in thermoregulation. In other species, it has been found that cooling may enhance the response of cutaneous vessels to 5-hydroxytryptamine (5-HT) and alpha(2)-adrenoceptor agonists. Translocation of alpha(2)-adrenoceptors to the smooth muscle cell membrane, mediated by Rho kinase, is thought to be involved in the cooling-enhanced response in mouse tail arteries. However, little is known about the effect of cooling on 5-HT receptor function. The present investigation compared the response of 5-bromo-6-(2-imidazolin-2-ylamino) quinoxaline (UK14304:1 nM to 30 microM), methoxamine (0.1 nM to 30 microM; in the presence of yohimbine 0.1 microM), 5-carboxamidotryptamine (5-CT; 0.1 nM to 10 microM) and alpha-methyl 5-HT (0.1 nM to 10 microM) in the isolated equine digital vein at 30 degrees C and 22 degrees C. The effect of the Rho kinase inhibitor, fasudil (1 microM), and the recovery of the response after the irreversible blockade of surface receptors with phenoxybenzamine (10 microM) or 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline (EEDQ;10 microM), was established. Moderate cooling significantly increased the maximum response to alpha-methyl 5-HT, 5-CT and UK14304 and shifted their response curves to the left. Cooling also augmented the phenoxybenzamine- and EEDQ-resistant response to UK14304 and 5-CT, respectively. Fasudil had no effect on the contractile response at 30 degrees C, but completely abrogated the effect of cooling on the response to 5-CT and UK14304. The response to methoxamine was not significantly affected by cooling. These results suggest that Rho kinase plays an important role in the cooling-enhanced response mediated by 5-HT(1B/D) receptors and alpha(2)-adrenoceptors. The exact mechanism by which Rho/Rho kinase enhances the functional responses mediated by these receptors in these vessels has yet to be determined.
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Affiliation(s)
- Hector Zerpa
- Department of Veterinary Basic Sciences, Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK
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Laleman W, Van Landeghem L, Severi T, Vander Elst I, Zeegers M, Bisschops R, Van Pelt J, Roskams T, Cassiman D, Fevery J, Nevens F. Both Ca2+ -dependent and -independent pathways are involved in rat hepatic stellate cell contraction and intrahepatic hyperresponsiveness to methoxamine. Am J Physiol Gastrointest Liver Physiol 2007; 292:G556-64. [PMID: 17008556 DOI: 10.1152/ajpgi.00196.2006] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In chronic liver injury, hepatic stellate cells (HSCs) have been implicated as regulators of sinusoidal vascular tone. We studied the relative role of Ca(2+)-dependent and Ca(2+)-independent contraction pathways in rat HSCs and correlated these findings to in situ perfused cirrhotic rat livers. Contraction of primary rat HSCs was studied by a stress-relaxed collagen lattice model. Dose-response curves to the Ca(2+) ionophore A-23187 and to the calmodulin/myosin light chain kinase inhibitor W-7 served to study Ca(2+)-dependent pathways. Y-27632, staurosporin, and calyculin (inhibitors of Rho kinase, protein kinase C, and myosin light chain phosphatase, respectively) were used to investigate Ca(2+)-independent pathways. The actomyosin interaction, the common end target, was inhibited by 2,3-butanedione monoxime. Additionally, the effects of W-7, Y-27632, and staurosporin on intrahepatic vascular resistance were evaluated by in situ perfusion of normal and thioacetamide-treated cirrhotic rat livers stimulated with methoxamine (n = 25 each). In vitro, HSC contraction was shown to be actomyosin based with a regulating role for both Ca(2+)-dependent and -independent pathways. Although the former seem important, an important auxiliary role for the latter was illustrated through their involvement in the phenomenon of "Ca(2+) sensitization." In vivo, preincubation of cirrhotic livers with Y-27632 (10(-4) M) and staurosporin (25 nM), more than with W-7 (10(-4) M), significantly reduced the hyperresponsiveness to methoxamine (10(-4) M) by -66.8 +/- 1.3%, -52.4 +/- 2.7%, and -28.7 +/- 2.8%, respectively, whereas in normal livers this was significantly less: -43.1 +/- 4.2%, -40.2 +/- 4.2%, and -3.8 +/- 6.3%, respectively. Taken together, these results suggest that HSC contraction is based on both Ca(2+)-dependent and -independent pathways, which were shown to be upregulated in the perfused cirrhotic liver, with a predominance of Ca(2+)-independent pathways.
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Affiliation(s)
- Wim Laleman
- Dept of Hepatology, Univ Hospital Gasthuisberg, K U Leuven, Leuven, Belgium
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Dincer UD, Araiza AG, Knudson JD, Molina PE, Tune JD. Sensitization of coronary alpha-adrenoceptor vasoconstriction in the prediabetic metabolic syndrome. Microcirculation 2006; 13:587-95. [PMID: 16990217 DOI: 10.1080/10739680600885228] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
OBJECTIVE This study tested whether alpha -adrenoceptor-mediated coronary vasoconstriction is augmented in the metabolic syndrome and is accompanied by the alteration of specific alpha(1)- and alpha(2)-coronary adrenoceptors. METHODS Studies were conducted in control and chronically high-fat-fed (6 weeks of 60% calories from fat) dogs with metabolic syndrome. Alterations in coronary alpha(1B)-, alpha(1D)-, and alpha(2A)-adrenoceptor mRNA and protein expression were examined by real-time PCR and Western analyses, respectively. Coronary blood flow and its response to intracoronary infusion of either the alpha1-adrenoceptor agonist methoxamine (0.1-3 mg) or the alpha(2)-adrenoceptor agonist BHT-933 (0.1-3 mg) were measured in anesthetized dogs. RESULTS Basal plasma epinephrine and norepinephrine levels were higher in the high-fat-fed dogs compared to controls. Real-time PCR revealed no alterations of coronary artery or arteriole alpha1B-, alpha(1D)-, and alpha(2A)-adrenoceptor mRNA expression. However, Western blot analysis showed a significant decrease in alpha(2A)-adrenoceptor protein density with no change in alpha(1B)- or alpha(1D)-adrenoceptors. Methoxamine and BHT-933 produced dose-dependent decreases in coronary blood flow, but the decrease in coronary flow to methoxamine was significantly greater (approximately 20%) in dogs with the metabolic syndrome. No differences in the coronary flow response to BHT-933 were noted. CONCLUSIONS These results indicate that the metabolic syndrome is associated with sensitization of alpha1- and alpha2-adrenoceptor signaling that could significantly limit control of coronary blood flow when the sympathetic nervous system is activated.
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Affiliation(s)
- U Deniz Dincer
- Department of Physiology, Louisiana State University Health Sciences Center, New Orleans, USA
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Abstract
1 Several imidazolines were examined for the antagonism of muscarinic (M3) and other receptors on the isolated ileum of guinea-pig. The effect of the muscarinic agonist, carbachol was competitively antagonized by oxymetazoline at 10(-5) m. A dissociation constant (KB) of 3.6 microm for the antagonist was calculated. At higher concentrations, 3 x 10(-5) and 10(-4) m, of the antagonist, the agonist dose-response curve was shifted to the right with a decrease in the maximum effect. Thus, a non-competitive block occurred at higher concentrations of oxymetazoline. Blockade of histamine H, and serotonin receptor-mediated responses by oxymetazoline were also of a non-competitive type. 2 Naphazoline at 10(-4) m shifted the dose-response curves of carbachol and serotonin to the right by two- and 15-fold, respectively. The maximum contraction of the agonist was not affected. Tolazoline also had a weak antihistaminic activity. At similar concentration; tetrahydrozoline clonidine and phentolamine at 10(-5) m produced two-, three- and four-fold shift of the carbachol dose-response curve without significant changes in the maxima. Neither methoxamine, p-amino-clonidine nor cimetidine blocked the responses of carbachol. 3 The isosteric nature of the alpha-adrenoceptor agonist, oxymetazoline and some imidazolines with carbachol, in part, explains its molecular competition at the muscarinic M3 receptor of the guinea-pig ileum. Surprisingly, contractile effects of carbachol (M3), histamine (H1) or serotonin (5HT3/5HT4) were not influenced by methoxamine, tetrahydrozoline, p-amino clonidine and cimetidine.
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Affiliation(s)
- M M Salazar-Bookaman
- Department of Pharmacology, College of Pharmacy, Universidad Central de Venezuela, Caracas, Venezuela
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Kamata K, Satoh T, Matsumoto T, Noguchi E, Taguchi K, Kobayashi T, Tanaka H, Shigenobu K. Enhancement of methoxamine-induced contractile responses of rat ventricular muscle in streptozotocin-induced diabetes is associated with alpha1A adrenoceptor upregulation. Acta Physiol (Oxf) 2006; 188:173-83. [PMID: 17054657 DOI: 10.1111/j.1748-1716.2006.01616.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
AIM To clarify the time-related changes in cardiac function and the mechanism underlying the cardiac dysfunction present in diabetes mellitus, we studied mechanical responses induced by alpha(1)- and beta-adrenoceptors, the Ca(2+)-entry promoter Bay K 8644- and ryanodine (an agent known to inhibit Ca(2+) release from the sarcoplasmic reticulum) in papillary muscles from streptozotocin (STZ)-induced diabetic and age-matched control rats. METHODS Male Wistar rats received a single injection of STZ (60 mg kg(-1)) via the tail vein to induce diabetes. For the mechanical studies, papillary muscle preparations were suspended in an organ bath and isometric contractions were measured in 1-, 4-, and 10-week STZ-induced diabetic and age-matched control rats. RESULTS In 1-week diabetic rats, the contractions induced by isoproterenol, methoxamine and Bay K 8644 were unchanged (vs. age-matched controls). In 4-week diabetic rats, (a) the isoproterenol- and Bay K 8644-induced contractions were impaired, (b) sensitivity to ryanodine was reduced, whereas (c) the methoxamine-induced contraction was unchanged. In 10-week diabetic rats, the isoproterenol- and Bay K 8644-induced contractile responses were impaired and the sensitivity to ryanodine was reduced, but in sharp contrast the methoxamine-induced contraction was enhanced. Both the mRNA level for the alpha(1A) adrenoceptor (but not the alpha(1B) or alpha(1D) mRNAs) and alpha(1A) adrenoceptor protein were increased in 10-week diabetic rats (vs. age-matched controls). CONCLUSION These results suggest that impairments of beta-adrenergic and Ca(2+)-handling mechanisms occur early in the development of cardiomyopathy in STZ-induced diabetic rats, and that this is followed by augmentation of alpha(1A) adrenoceptor-mediated inotropy due to alpha(1A) adrenoceptor upregulation.
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Affiliation(s)
- K Kamata
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Tokyo, Japan.
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Hasumi H, Matsuda R, Shimamoto K, Hata Y, Kaneko N. K201, a multi-channel blocker, inhibits clofilium-induced torsades de pointes and attenuates an increase in repolarization. Eur J Pharmacol 2006; 555:54-60. [PMID: 17112502 DOI: 10.1016/j.ejphar.2006.10.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2006] [Revised: 10/03/2006] [Accepted: 10/05/2006] [Indexed: 11/16/2022]
Abstract
K201 (JTV519) is a 1,4-benzothiazepine derivative that exhibits a strong cardioprotective action and acts as a multiple-channel blocker, including as a K+ channel blocker. An experimental model of prolongation of the QT interval and torsades de pointes can be induced in rabbits by treatment with clofilium in the presence of the alpha1-adrenoreceptor agonist methoxamine. In this study we examined the effects of K201 with and without methoxamine on the QT and QTc intervals, and determined whether K201 inhibits clofilium-induced torsades de pointes in the presence of methoxamine (15 microg/kg/min) in rabbits (n=74). Administration of K201 (0, 40, 100, 200 and 400 microg/kg/min) with and without methoxamine prolonged the QT interval in a dose-dependent manner, and torsades de pointes did not occur in any animals. However, clofilium (50 microg/kg/min) with methoxamine induced torsades de pointes in all animals (6/6). Torsades de pointes occurred at rates of 100%, 67%, 40% and 0% at K201 concentrations of 0, 50, 200 and 400 microg/kg/min, respectively, in the clofilium-infused torsades de pointes model. Therefore, 400 microg/kg/min of K201 completely inhibited clofilium-induced torsades de pointes and attenuated the increase of repolarization caused by clofilium; the inhibitory effects of K201 may be related to its pharmacological properties as an alpha1-adrenoceptor blocker. Overall, our results show that K201 causes prolongation of the QT and QTc intervals, but does not induce torsades de pointes, with and without alpha1-adrenoceptor stimulation. Furthermore, K201 inhibits clofilium-induced torsades de pointes, despite QT prolongation, suggesting that QT prolongation alone is not a proarrhythmic signal.
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Affiliation(s)
- Hisashi Hasumi
- Department of Cardiology and Pneumology, Dokkyo Medical University School of Medicine 880 Kitakobayashi, Mibu, Tochigi, Japan
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Mizuta K, Mizuta F, Takahashi M, Ishii H, Niioka T, Izumi H. Effects of isoflurane on parasympathetic vasodilatation in the rat submandibular gland. J Dent Res 2006; 85:379-83. [PMID: 16567563 DOI: 10.1177/154405910608500419] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Volatile anesthetics have been known to suppress parasympathetic reflex vasodilatation in the lower lip and palate. However, in the submandibular gland, little is known about the effects of these anesthetics on the parasympathetic vasodilatation elicited by reflex and direct (i.e., non-reflex) activation of the parasympathetic vasodilator mechanisms. Although both parasympathetic vasodilatations were inhibited by isoflurane in a concentration- and time-dependent manner, the effects of continuous administration of the alpha(1)-adrenoceptor agonist methoxamine were markedly different: The reflex vasodilatation was not affected by methoxamine, while the direct vasodilatation was significantly reduced. Picrotoxin (GABA(A) receptor antagonist) attenuated the inhibitory effect of isoflurane on direct vasodilatation and the systemic arterial blood pressure. These findings suggest that the isoflurane-induced inhibitory effects on direct vasodilatation are produced by a decrease of peripheral vascular tone by GABAergic mechanisms, whereas those on the reflex vasodilatation are produced exclusively by the inhibition of the reflex center.
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Affiliation(s)
- K Mizuta
- Division of Dento-Oral Anesthesiology, Tohoku University Graduate School of Dentistry, Aoba, Sendai, 980-8575, Japan
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Alsene KM, Carasso BS, Connors EE, Bakshi VP. Disruption of prepulse inhibition after stimulation of central but not peripheral alpha-1 adrenergic receptors. Neuropsychopharmacology 2006; 31:2150-61. [PMID: 16407904 DOI: 10.1038/sj.npp.1300989] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Prepulse inhibition (PPI) refers to the attenuation of startle when a weak prestimulus precedes the startling stimulus. PPI is deficient in several psychiatric illnesses involving poor sensorimotor gating. Previous studies indicate that alpha1 adrenergic receptors regulate PPI, yet the extent to which these effects are mediated by central vs peripheral receptors is unclear. The present studies compared the effects of intracerebroventricular (ICV) vs intraperitoneal (IP) delivery of several alpha1 receptor agonists on PPI. Male Sprague-Dawley rats received either cirazoline (0, 10, 25, 50 microg/5 microl), methoxamine (0, 30, 100 microg/5 microl), or phenylephrine (0, 3, 10, 30 microg/5 microl) ICV immediately before testing. Separate groups received either cirazoline (0, 0.25, 0.50, 0.75 mg/kg), methoxamine (0, 2, 5, 10 mg/kg), or phenylephrine (0, 0.1, 2.0 mg/kg) IP 5 min before testing. PPI, baseline startle responses, and piloerection, an index of autonomic arousal, were measured. Cirazoline disrupted PPI; effective ICV doses were approximately six times lower than effective IP doses. Methoxamine disrupted PPI after ICV infusion but failed to affect PPI with IP doses that were up to 30-fold higher than the effective ICV dose. Phenylephrine disrupted PPI with ICV administration, but did not alter PPI after IP injection of even a 20-fold higher dose. None of the ICV treatments altered baseline startle magnitude, but phenylephrine and methoxamine lowered startle after administration of high systemic doses. Piloerection was induced by cirazoline via either route of administration, and by IP methoxamine and phenylephrine, but not by ICV infusion of methoxamine or phenylephrine. These findings indicate that alpha1 receptor-mediated PPI disruption occurs exclusively through stimulation of central receptors and is dissociable from alterations in baseline startle or autonomic effects.
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MESH Headings
- Acoustic Stimulation/methods
- Adrenergic alpha-Agonists/administration & dosage
- Adrenergic alpha-Antagonists/administration & dosage
- Analysis of Variance
- Animals
- Behavior, Animal
- Conditioning, Classical/drug effects
- Dose-Response Relationship, Drug
- Dose-Response Relationship, Radiation
- Imidazoles/pharmacology
- Infusions, Parenteral
- Injections, Intraventricular
- Male
- Methoxamine/pharmacology
- Neural Inhibition/drug effects
- Neural Inhibition/physiology
- Phenylephrine/pharmacology
- Piloerection/drug effects
- Prazosin/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptors, Adrenergic, alpha-1/physiology
- Reflex, Startle/drug effects
- Reflex, Startle/physiology
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Affiliation(s)
- Karen M Alsene
- Department of Psychiatry and Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI 53719, USA
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37
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Jiang MC, Heckman CJ. In vitro sacral cord preparation and motoneuron recording from adult mice. J Neurosci Methods 2006; 156:31-6. [PMID: 16574242 DOI: 10.1016/j.jneumeth.2006.02.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Revised: 02/02/2006] [Accepted: 02/02/2006] [Indexed: 01/07/2023]
Abstract
We report the development of an intracellular recording technique for adult mouse motoneurons in sacral spinal cord. Based on a similar preparation for adult rat, we modified the cord preparation solution and filled the sharp electrode with a solution that has physiological osmolarity and pH. The viability of the preparation was examined by recording root reflexes. Short-latency reflexes mediated through monosynaptic transmission between S1 and S3 ventral root were reliably produced by dorsal root electrical stimuli and were stably recorded for more than eight hours. Long-lasting potentiation of the root reflex was observed by bath application of methoxamine, a noradrenergic alpha1 receptor agonist. Bath application of strychnine and picrotoxin, antagonists for glycine and GABA(A) receptors respectively, unmasked long-lasting reflexes that may contain polysynaptic components. In addition, on the background of strychnine and picrotoxin, adding methoxamine induced spontaneous ventral root activity. For intracellular recording, the motoneurons could be reliably penetrated and held for up to 30 min. In all 16 motoneurons recorded, resting membrane potential, input resistance, action potentials and repetitive firing were comparable to those of rat motoneurons. Thus, this preparation is viable and provides a new method for combined electrophysiological and genetic studies of the adult mouse spinal cord.
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Affiliation(s)
- M C Jiang
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
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Zhou Q, Hennenberg M, Trebicka J, Jochem K, Leifeld L, Biecker E, Sauerbruch T, Heller J. Intrahepatic upregulation of RhoA and Rho-kinase signalling contributes to increased hepatic vascular resistance in rats with secondary biliary cirrhosis. Gut 2006; 55:1296-305. [PMID: 16492715 PMCID: PMC1860046 DOI: 10.1136/gut.2005.081059] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND AND AIMS Portal hypertension in cirrhosis is mediated in part by increased intrahepatic resistance, reflecting an increased sensitivity of the hepatic microvasculature to vasoconstrictors. Activation of the RhoA/Rho-kinase pathway is essential for contraction of vascular smooth muscle. The aim of this study was to investigate RhoA/Rho-kinase mediated regulation of the intrahepatic vascular tone in cirrhotic rats. METHODS Cirrhosis was induced by bile duct ligation (BDL). Hepatic RhoA and Rho-kinase expressions were studied by real time reverse transcription polymerase chain reaction and western blot analysis. Hepatic Rho-kinase activity in rat and human livers was assessed as phosphorylation of the Rho-kinase substrate moesin. The effect of the Rho-kinase inhibitor Y-27632 on hepatic perfusion pressure was measured in livers perfused at constant flow. The in vivo effect of intravenous application of Y-27632 was studied by haemodynamic measurements. RESULTS Hepatic expressions of RhoA and Rho-kinase were increased at mRNA and protein level in BDL rats. Intrahepatic moesin phosphorylation was increased in livers from cirrhotic rats and patients with alcohol induced cirrhosis. Y-27632 reduced the basal perfusion pressure of in situ perfused livers in BDL rats but not in sham operated rats. Y-27632 reduced the sensitivity to methoxamine in isolated perfused livers in sham operated rats more than in BDL rats. In vivo, Y-27632 reduced portal pressure to a greater extent in BDL rats than in sham operated rats. Intrahepatic vascular resistance was decreased in response to bolus injection of Y-27632 in BDL rats but not in sham operated rats. CONCLUSIONS Upregulation of RhoA and Rho-kinase contributes to increased intrahepatic resistance in cirrhotic rats and to an increased sensitivity of cirrhotic livers to vasoconstrictors.
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Affiliation(s)
- Q Zhou
- Department of Internal Medicine I, University of Bonn, Sigmund-Freud-Str 25, D-53105 Bonn, Germany
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Kumar VM, Vetrivelan R, Mallick HN. Alpha-1 adrenergic receptors in the medial preoptic area are involved in the induction of sleep. Neurochem Res 2006; 31:1095-102. [PMID: 16933152 DOI: 10.1007/s11064-006-9109-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/30/2006] [Indexed: 02/04/2023]
Abstract
This paper reviews the recent studies that led to the conclusion that the noradrenergic neurons projecting to the medial preoptic area (mPOA) are hypnogenic and that they mediate this action through alpha(1) adrenergic receptors. Microinjection of noradrenaline (NA) into the mPOA induced arousal. Studies using alpha(2) adrenergic drugs showed that the arousal induced by intrapreoptic injection of NA was due to its action on presynaptic alpha(2) adrenergic receptors. A combination of lesion and chemical stimulation techniques demonstrated that when NA acted on the postsynaptic alpha(1 )receptors in the mPOA, it induced sleep. Intrapreoptic injection of alpha(1) agonist, methoxamine could induce sleep, when the hypothermia, which was simultaneously produced, was behaviorally compensated for by the animal. Increased arousal produced by the destruction of noradrenergic fibers in the mPOA further confirmed the hypnogenic role of these fibers.
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Affiliation(s)
- Velayudhan Mohan Kumar
- Department of Physiology, All India Institute of Medical Sciences, New Delhi 110029, India.
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Castillo EF, Ortíz CS, López RM, Ruíz A, Vélez JM, Castillo C. Evidence against alpha2-adrenoceptors mediating relaxation in rat thoracic aortae: alpha2-agonists relaxation depends on interaction with alpha1-adrenoceptors. Fundam Clin Pharmacol 2006; 20:339-49. [PMID: 16867017 DOI: 10.1111/j.1472-8206.2006.00421.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In rat aorta, the presence of functional alpha(2)-adrenoceptors (alpha(2)-AR) was investigated in ring preparations preconstricted with alpha(1)-adrenergic and non- alpha(1)-adrenergic agonists. Particularly, the hypothetical interference of alpha(2)-AR agonists with alpha(1)-AR-mediated vasoconstriction was evaluated. Relaxant and contractile responses to alpha(2)-AR agonists were obtained. In endothelium-intact and endothelium-denuded aortic rings preconstricted with phenylephrine (1 x 10(-6) m), the imidazoline derivatives, clonidine and UK14304, induced relaxations with similar order of potencies (-log EC(50)) and maxima relaxant effects respectively. Pretreatment with the NO synthase inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME) had no effect on the relaxant responses to clonidine and UK14304. In phenylephrine-constricted rings with endothelium, relaxations to clonidine and UK 14304 were not antagonized by the selective alpha(2)-AR antagonist, rauwolscine (< or =1 x 10(-6) m). Clonidine and UK 14304 induced only contractions on endothelium-intact and endothelium-denuded aortic rings contracted with prostaglandin F(2alpha) (3 x 10(-7) m). Moreover, clonidine and UK 14304-induced relaxation of endothelium-denuded arteries precontracted with methoxamine but not with serotonin. Finally, the concentration-contraction curves to clonidine and UK 14304 in endothelium-denuded aortic rings were significantly shifted to the right by the alpha(1D)-AR selective antagonist, BMY 7378, and rauwolscine. The pA(2) and pK(B) values for BMY 7378 and rauwolscine, respectively, against endothelium-independent actions of clonidine and UK 14304 were characteristic of an effect on the alpha(1D)-AR. The other selective alpha(2)-AR agonist tested BHT 933 (an azepine derivative), lacks considerable relaxant and contractile effects in rat aorta. The results provide no evidence for the presence of functional alpha(2)-AR in rat aorta. Respectively, the relaxant and contractile effects of the imidazoline derivatives, clonidine and UK 14304, may be due to an adjustable (in relation to the agonist-dependent active state of the alpha(1)-AR), inhibitory and excitatory, interaction with alpha(1)-ARs.
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MESH Headings
- Adrenergic alpha-Agonists/pharmacology
- Adrenergic alpha-Antagonists/pharmacology
- Animals
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/metabolism
- Azepines/pharmacology
- Brimonidine Tartrate
- Clonidine/pharmacology
- Dinoprost/pharmacology
- Dose-Response Relationship, Drug
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/metabolism
- In Vitro Techniques
- Male
- Methoxamine/pharmacology
- Nitric Oxide/metabolism
- Phenylephrine/pharmacology
- Piperazines/pharmacology
- Quinoxalines/pharmacology
- Rats
- Rats, Wistar
- Receptors, Adrenergic, alpha-1/drug effects
- Receptors, Adrenergic, alpha-1/metabolism
- Receptors, Adrenergic, alpha-2/drug effects
- Receptors, Adrenergic, alpha-2/metabolism
- Serotonin/pharmacology
- Vasoconstrictor Agents/pharmacology
- Vasodilation/drug effects
- Yohimbine/pharmacology
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Affiliation(s)
- Enrique F Castillo
- Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, México, DF, México.
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Elverdin JC, Chiarenza AP, Luchelli MA, Vatta M, Bianciotti LG, Boyer P, Vacas MI. Protein free diet feeding: Effects on sympathetic activity and salivary evoked secretion in the submandibular gland of the rat. Arch Oral Biol 2006; 51:621-8. [PMID: 16600171 DOI: 10.1016/j.archoralbio.2006.02.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2005] [Revised: 01/03/2006] [Accepted: 02/01/2006] [Indexed: 11/24/2022]
Abstract
Protein restriction impairs the salivary flow rate and composition in human and rats. The aim of the present work was to establish the effect of low protein (casein 5%) and protein free (casein 0%) isocaloric diets on sympathetic activity and salivary evoked secretion in the submandibular gland (SMG) of the rat. After 21 days, rats fed casein 0% presented: (a) a significant shift to the left of the dose-response curves (DRC) to the autonomic agonists-norepinephrine (NE), methoxamine, isoproterenol (ISO) and methacholine; (b) increased food consumption (p<0.001); (c) decreased body (p<0.001) and SMG (p<0.001) weights maintaining SMG/body (w/w) relation; (d) enhanced submandibular alpha1-adrenoceptor number without changes in the apparent dissociation constant (Kd); (e) increased submandibular NE content (p<0.05) and phosphoinositoside hydrolysis (p<0.001); (f) decreased submandibular tyrosine hydroxylase activity (TH) (p<0.01). Casein 5% feeding increased food consumption (p<0.01) and reduced body weight (p<0.05). This protein restriction increased metacholine-evoked salivation, but it altered neither submandibular sympathetic activity nor sympathetic-induced salivary secretion as compared to the Control group (C) fed a similar diet containing 25.5% protein. Present results suggest that in the adult rat, a protein free diet during 21 days lowers SMG sympathetic and cholinergic activity leading to supersensitivity as revealed by up-regulation of alpha1-adrenergic receptor number and increased autonomic-evoked salivation.
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Affiliation(s)
- Juan C Elverdin
- Cátedra de Fisiología, Facultad de Odontología, Universidad de Buenos Aires, M.T. de Alvear 2142, 3(er) Piso A (CP1122), Buenos Aires, Argentina.
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Farkas AS, Acsai K, Tóth A, Dézsi L, Orosz S, Forster T, Csanády M, Papp JG, Varró A, Farkas A. Importance of extracardiac alpha1-adrenoceptor stimulation in assisting dofetilide to induce torsade de pointes in rabbit hearts. Eur J Pharmacol 2006; 537:118-25. [PMID: 16618484 DOI: 10.1016/j.ejphar.2006.03.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2005] [Revised: 03/08/2006] [Accepted: 03/10/2006] [Indexed: 10/24/2022]
Abstract
In anaesthetized rabbits, alpha(1)-adrenoceptor stimulation increases the propensity of repolarization-prolonging drugs to induce torsade de pointes ventricular tachycardia. However, it is not known whether the stimulation of intracardiac alpha(1)-adrenoceptors, or the increased ventricular stretch caused by extracardiac alpha(1)-adrenoceptor-mediated peripheral vasoconstriction and increased resistance, are the sensitizing factors. Accordingly, this study investigated whether a sustained load-induced left ventricular stretch or stimulation of the intracardiac alpha(1)-adrenoceptors with 100 nM methoxamine, or the co-application of these two, can assist dofetilide (100 nM) to elicit torsade de pointes in isolated Langendorff-perfused, rabbit hearts. In the stretched hearts, a constant high level of stretch was produced by a water-filled left ventricular balloon inflated to a volume of 1.4 ml, whereby the systolic and end-diastolic pressures virtually did not exceed the physiological range (<or=157+/-11 mm Hg and <or=9+/-2 mm Hg, respectively; mean+/-S.E.M.). Perfusion with dofetilide prolonged the QT interval significantly and indifferently in all hearts. Neither this stretch nor methoxamine nor the in combination affected the QT interval, the heart rate or the coronary flow. Interestingly, neither the stretch ('dofetilide+stretch' group, n=8 hearts), nor methoxamine ('dofetilide+methoxamine' group, n=8 hearts), nor the in combination ('dofetilide+stretch+methoxamine' group, n=8 hearts) elevated the incidence of torsade de pointes as compared with the 'dofetilide alone' group (n=9 hearts) (0%, 25%, 0%, versus 44%, respectively). In conclusion, neither a sustained load-induced stretch nor alpha(1)-adrenoceptor stimulation nor the in combination assisted dofetilide to induce torsade de pointes in isolated rabbit hearts, suggesting the importance of extracardiac alpha(1)-adrenoceptor stimulation in this phenomenon.
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Affiliation(s)
- Attila S Farkas
- 2nd Department of Internal Medicine and Cardiology Centre, Faculty of Medicine, University of Szeged, Korányi fasor 6., Szeged, H-6701, Hungary
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Chu YH, Wu CC, Kao CH, Wang HW. Low temperature decreased tension in isolated hypertrophic human nasal mucosa. Am J Rhinol 2006; 20:84-6. [PMID: 16539300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
BACKGROUND The purpose of this study was to evaluate the effect of low temperature on basal tension in isolated hypertrophic human nasal mucosa with or without alpha1-agonist stimulation. METHODS A tissue bath for isolated nasal mucosa was used. Tension in strips of human turbinate mucosa that were untreated and treated with an alpha1-adrenoreceptor agonist, methoxamine (10 microM), was recorded continuously in a stepwise manner in temperatures that varied from 37 to 10 degrees C. RESULTS The changes of tension in the human nasal mucosa were found to be temperature-dependent in both untreated and treated tissues, with tension decreasing to 48.6% at 10 degrees C in comparison with 100% at 37 degrees C in the untreated group, the presence of methoxamine (10 microM) had minimal effect. CONCLUSION Low temperature induced a rapid and reproducible relaxation in isolated hypertrophic human nasal mucosa that was not affected by the presence of the alpha1-agonist methoxamine (10 microM).
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Affiliation(s)
- Yueng-Hsiang Chu
- Graduate Institute of Medical Sciences, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China
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Abstract
The steadily increasing list of drugs associated with prolongation of the QT interval and torsades de pointes (TdP) constitute a medical problem of major concern. Hence, there is a need at an early stage to identify drug candidates with an inherent capacity to induce repolarization-related proarrhythmias, avoiding exposure of large populations to potentially harmful drugs. Furthermore, the availability of clinically relevant and predictive animal models should reduce the risk that effective and potentially life-saving drugs never reach the market. This review will discuss the pros and cons of some in vivo and in vitro animal models for assessing proarrhythmia liability.
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Affiliation(s)
- L Carlsson
- AstraZeneca R&D Mölndal, Integrative Pharmacology, Mölndal, Sweden.
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Wang HW, Kao CH, Chu YH. A new in vitro method of decongestant assay of nasal mucosa: a preliminary report. Am J Rhinol 2006; 20:43-7. [PMID: 16539294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
BACKGROUND The calculation of cell planar surface area, successfully used for glomerular mesangial cell-altered contractility, also is a reasonable methodology to assess nasal mucosal contractility. A simple technique that works particularly well with vasoconstriction-inducing agents has been introduced to test the effects of several drugs on patient turbinate nasal mucosa in vitro. This report will introduce this technique and present some of the initial findings. METHODS We tested epinephrine, norepinephrine, pseudoephedrine HCl, and methoxamine, respectively, for effectiveness as a vasoconstricting drug. We also tested the effectiveness of verapamil as a vasodilating drug. A piece of nasal mucosa approximately 3 x 4 mm in size was mounted with a 27-gauge needle and submersed in a 4-mL muscle bath in a Petri dish at room temperature. The bath consisted of 4 mL of Kreb's solution. We recorded the decrease of nasal mucosa planar surface area in response to the application of vasoconstricting agents, as measured using a digital microscope connected to a Pentium III with morphometric software, as the estimated degree of contraction. A photograph of the same mucosa was taken every 3 minutes for a total period of 18 minutes. RESULTS Nasal mucosa that was mounted in a muscle bath in a Petri dish and treated with a small dose of a nasal decongestant was l observed to contract. Drug dosage determined the degree of nasal mucosa contraction. Nasal mucosa similarly prepared but treated with a vasodilating agent, such as verapamil, exhibited a relaxation response only when pretreated with a vasoconstricting agent, such as methoxamine. Both vasoconstricting and vasodilating drugs induce dose-related responses in planar surface calculation. CONCLUSION In this study, drug dosage determined the degree of nasal mucosa contraction. We also found that the rate of contraction and percent of contraction were dose dependent. We believe this new method will prove useful in studying the effects of drugs on nasal blood vessels.
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Affiliation(s)
- Hsing-Won Wang
- Department of Otolaryngology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China.
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Atucha NM, Nadal FJA, Alcaraz A, Iyú D, Ortiz MC, García-Estañ J. Reduced capacitative calcium entry in the mesenteric vascular bed of bile duct-ligated rats. Eur J Pharmacol 2005; 525:117-22. [PMID: 16266702 DOI: 10.1016/j.ejphar.2005.09.046] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2005] [Revised: 09/20/2005] [Accepted: 09/27/2005] [Indexed: 11/20/2022]
Abstract
In this work, we analyzed the interaction of nitric oxide (NO) with some of the mechanisms known to regulate intracellular calcium levels in order to gain insight into the mechanisms responsible for the reduced vascular pressor response to vasoconstrictors observed in an experimental model of liver cirrhosis. Specifically, we hypothesized that the entry of calcium through capacitative channels is defective in this model. The experiments were performed with isolated, Krebs-perfused and de-endothelialized mesenteric arterial bed of rats with bile duct ligation (4 weeks) and their controls. Pretreatment with thapsigargin to inhibit calcium uptake into sarcoplasmic reticulum potentiated the pressor responses to methoxamine, but the response of the cirrhotic vessels was significantly lower than that of the controls. Under the same conditions, perfusion of the mesenteries with zero calcium-Krebs resulted in lower pressor responses to methoxamine, especially in the mesenteries of the bile duct-ligated rats. To specifically analyze the entry of calcium through store-operated calcium channels, the pressor response to the addition of calcium was studied in mesenteries perfused with zero calcium-Krebs and in the presence of thapsigargin. Again, the response of the cirrhotic mesenteric beds was significantly lower than that of the control vessels. Under all these experimental conditions, the differences between control and cirrhotic responses were abolished by pretreatment with the NO synthesis inhibitor N(w)-nitro-L-arginine (NNA). These results indicate that, in the mesenteric bed of bile duct-ligated rats, an excess of nitric oxide interferes with the release of calcium from thapsigargin-sensitive internal stores and also reduces the capacitative entry of calcium into vascular muscular cells induced by the depletion of calcium from internal stores. This mechanism may have an important role in the reduced pressor response observed in the mesenteric vascular bed in cirrhosis.
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Affiliation(s)
- Noemí M Atucha
- Departamento de Fisiología, Facultad de Medicina, 30100 Murcia, Spain
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Abstract
We found when L-type calcium current (ICa-L) was recorded with the perforated patch-clamp method in rat ventricular myocytes that bath application of phenylephrine (with propranolol) evoked a biphasic response characterized by an initial transient suppression followed by a sustained potentiation. The transient suppression occurred 30–60 s after phenylephrine perfusion and reached peak inhibition at approximately 2 min. The biphasic modulation of ICa-Lwas also elicited by methoxamine, and the effects of phenylephrine were blocked by prazosin, indicating that the responses were mediated through α1-adrenoceptors. Pretreatment of cells with H7 (100 µmol/L), a broad-spectrum protein kinase inhibitor that inhibits both protein kinase C and A, eliminated potentiation but did not affect transient suppression. The transient suppression occurred concurrently with the acceleration of the fast component of ICa-Linactivation. Depletion of intracellular Ca2+stores by ryanodine plus caffeine or thapsigargin eliminated the transient suppression. When ICa-Lwas recorded with whole-cell patch-clamp and with 0.05 mmol/L EGTA in the pipette solution to allow intracellular Ca2+to fluctuate, phenylephrine evoked a transient suppression as in the perforated patch recordings. Heparin, a specific blocker of IP3(inositol 1,4,5-trisphosphate) receptors, eliminated the phenylephrine-induced transient suppression of ICa-Lwhen added to the pipette solution. Intensive chelation of intracellular Ca2+by 5 mmol/L BAPTA (1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid) in the pipette solution also eliminated the phenylephrine-induced transient suppression of ICa-L. We conclude that transient increase in the concentration of intracellular calcium ([Ca2+]i) caused by Ca2+release from intracellular stores underlies the transient suppression of ICa-L, whereas the potentiation of ICa-Lis a result of activation of protein kinases.Key words: Ca2+mobilization, IP3, Ca2+-induced inactivation of Ca2+current, perforated patch-clamp.
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Affiliation(s)
- Shetuan Zhang
- Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre and Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, MB, Canada.
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Nisar PJ, Gruss HJ, Bush D, Barras N, Acheson AG, Scholefield JH. Intra-anal and rectal application of l-erythro methoxamine gel increases anal resting pressure in healthy volunteers. Br J Surg 2005; 92:1539-45. [PMID: 16231282 DOI: 10.1002/bjs.5171] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Abstract
Background
This study examined the effect of a single local application of l-erythro methoxamine, an α1-adrenoceptor agonist, on mean anal resting pressure (MARP) and cardiovascular variables in healthy volunteers.
Methods
l-Erythro methoxamine gel was administered in a single-blind manner; 0·3–3 per cent gels were applied perianally (n = 12), 1–3 per cent gels intra-anally (n = 16) and 1 per cent gel rectally (n = 8). MARP, systolic blood pressure, diastolic blood pressure and pulse rate were measured before application and for up to 6 h afterwards. Blood samples were taken to estimate plasma drug levels.
Results
Perianal gel produced no increase in MARP. Intra-anal 1 per cent and 3 per cent gel produced a significant rapid rise in MARP for 4 and 5 h respectively after application (P = 0·012 and P = 0·017 respectively). Rectal 1 per cent gel increased MARP for 2 h after application (P = 0·036). Intra-anal gel resulted in an increase in systolic blood pressure (1 per cent gel at 2 h, P = 0·042; 3 per cent gel at 4 h, P = 0·017). One per cent intra-anal and rectal gels caused a decrease in the pulse rate for 2 h after application (P = 0·012 and P = 0·018 respectively). Six subjects complained of nausea and three of headache after gel application.
Conclusion
Intra-anal and rectal gel produced a sustained rise in MARP with rapid onset in volunteers. This raises the possibility of a therapeutic application for l-erythro methoxamine in patients with passive incontinence and internal anal sphincter dysfunction.
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Affiliation(s)
- P J Nisar
- Section of Surgery, University Hospital, Queen's Medical Centre, Nottingham NG7 2UH, UK.
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Marucci G, Angeli P, Buccioni M, Gulini U, Melchiorre C, Sagratini G, Testa R, Giardinà D. (+)-Cyclazosin, a selective α1B-adrenoceptor antagonist: Functional evaluation in rat and rabbit tissues. Eur J Pharmacol 2005; 522:100-7. [PMID: 16213480 DOI: 10.1016/j.ejphar.2005.08.044] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2005] [Revised: 08/08/2005] [Accepted: 08/29/2005] [Indexed: 11/28/2022]
Abstract
To shed light on the discrepancy between reported binding and functional affinity and selectivity at alpha(1b/B)-adrenoceptors, the antagonist (+)-cyclazosin was reinvestigated in rat and rabbit tissues. It displayed a competitive antagonism at alpha(1A) and alpha(1D)-adrenoceptors of rat prostatic vas deferens and aorta with pA(2) values 7.75 and 7.27, respectively. In rabbit thoracic aorta (+)-cyclazosin competitively antagonized noradrenaline-induced contractions at alpha(1B)-adrenoceptors with a pA(2) value of 8.85, whereas its affinity at alpha(1L)-adrenoceptors was markedly lower (pA(2) = 6.75-7.09). In conclusion, these data confirmed that (+)-cyclazosin is a selective alpha(1B)-adrenoceptor antagonist also in functional assays, showing 13- and 38-fold selectivity for the alpha(1B)-adrenoceptor over alpha(1A)- and alpha(1D)-subtypes, respectively. Furthermore, (+)-cyclazosin displayed a significant selectivity for alpha(1B)-adrenoceptors relative to the alpha(1L)-subtype.
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Brock JA, Yeoh M, McLachlan EM. Enhanced neurally evoked responses and inhibition of norepinephrine reuptake in rat mesenteric arteries after spinal transection. Am J Physiol Heart Circ Physiol 2005; 290:H398-405. [PMID: 16143650 DOI: 10.1152/ajpheart.00712.2005] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In patients with high thoracic spinal lesions that remove most of the central drive to splanchnic preganglionic neurons, visceral or nociceptive stimuli below the lesion can provoke large increases in blood pressure (autonomic dysreflexia). We have examined the effects of T4 spinal transection on isometric contractions of mesenteric arteries isolated from spinalized rats. Nerve-evoked contractions involved synergistic roles for norepinephrine and ATP. At 7 wk after spinal transection, responses to perivascular stimulation at 1-5 Hz were enhanced fivefold, whereas the alpha1-adrenoceptor antagonist prazosin (10 nM) produced a twofold larger reduction in contraction (to 20 pulses at 10 Hz) than in unoperated controls. In contrast, the reduction in nerve-evoked contractions by the P2-purinoceptor antagonist suramin (0.1 mM) and the responses to the P2-purinoceptor agonist alpha,beta-methylene ATP or to high K+ concentration did not greatly differ between groups, indicating that arteries from spinalized rats were not generally hyperreactive. Sensitivity to the alpha1-adrenoceptor agonist phenylephrine was enhanced in arteries from spinalized rats, and the difference from controls was abolished by the norepinephrine uptake blocker desmethylimipramine. Sensitivity to the alpha1-adrenoceptor agonist methoxamine, which is not a substrate for the neuronal norepinephrine transporter, was similar among the groups. Thus the increased neurally evoked response after spinal transection appeared to be due to a reduction in neuronal uptake of released norepinephrine, a mechanism that did not explain the enhanced response of tail arteries after spinal transection that we previously reported. The findings provide further support for potentiated neurovascular responses contributing to the genesis of autonomic dysreflexia.
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Affiliation(s)
- James A Brock
- Prince of Wales Medical Research Institute, University of New South Wales, Randwick, NSW 2031, Australia.
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