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DeLalio LJ, Stocker SD. Impact of anesthesia and sex on sympathetic efferent and hemodynamic responses to renal chemo- and mechanosensitive stimuli. J Neurophysiol 2021; 126:668-679. [PMID: 34259043 DOI: 10.1152/jn.00277.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Activation of renal sensory nerves by chemo- and mechanosensitive stimuli produces changes in efferent sympathetic nerve activity (SNA) and arterial blood pressure (ABP). Anesthesia and sex influence autonomic function and cardiovascular hemodynamics, but it is unclear to what extent anesthesia and sex impact SNA and ABP responses to renal sensory stimuli. We measured renal, splanchnic, and lumbar SNA and ABP in male and female Sprague-Dawley rats during contralateral renal infusion of capsaicin and bradykinin or during elevation in renal pelvic pressure. Responses were evaluated with a decerebrate preparation or Inactin, urethane, or isoflurane anesthesia. Intrarenal arterial infusion of capsaicin (0.1-30.0 μM) increased renal SNA, splanchnic SNA, or ABP but decreased lumbar SNA in the Inactin group. Intrarenal arterial infusion of bradykinin (0.1-30.0 μM) increased renal SNA, splanchnic SNA, and ABP but decreased lumbar SNA in the Inactin group. Elevated renal pelvic pressure (0-20 mmHg, 30 s) significantly increased renal SNA and splanchnic SNA but not lumbar SNA in the Inactin group. In marked contrast, SNA and ABP responses to every renal stimulus were severely blunted in the urethane and decerebrate groups and absent in the isoflurane group. In the Inactin group, the magnitude of SNA responses to chemo- and mechanosensory stimuli were not different between male and female rats. Thus, chemo- and mechanosensitive stimuli produce differential changes in renal, splanchnic, and lumbar SNA. Experimentally, future investigations should consider Inactin anesthesia to examine sympathetic and hemodynamic responses to renal sensory stimuli.NEW & NOTEWORTHY The findings highlight the impact of anesthesia, and to a lesser extent sex, on sympathetic efferent and hemodynamic responses to chemosensory and mechanosensory renal stimuli. Sympathetic nerve activity (SNA) and arterial blood pressure (ABP) responses were present in Inactin-anesthetized rats but largely absent in decerebrate, isoflurane, or urethane preparations. Renal chemosensory stimuli differentially changed SNA: renal and splanchnic SNA increased, but lumbar SNA decreased. Future investigations should consider Inactin anesthesia to study SNA and hemodynamic responses to renal sensory nerve activation.
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Affiliation(s)
- Leon J DeLalio
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Sean D Stocker
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
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DeLalio LJ, Stocker SD. Impact of anesthesia, sex, and circadian cycle on renal afferent nerve sensitivity. Am J Physiol Heart Circ Physiol 2021; 320:H117-H132. [PMID: 33216622 PMCID: PMC7847066 DOI: 10.1152/ajpheart.00675.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 11/17/2020] [Accepted: 11/17/2020] [Indexed: 01/09/2023]
Abstract
Elevated renal afferent nerve (ARNA) activity or dysfunctional reno-renal reflexes via altered ARNA sensitivity contribute to hypertension and chronic kidney disease. These nerves contain mechano- and chemosensitive fibers that respond to ischemia, changes in intrarenal pressures, and chemokines. Most studies have utilized various anesthetized preparations and exclusively male animals to characterize ARNA responses. Therefore, this study assessed the impact of anesthesia, sex, and circadian period on ARNA responses and sensitivity. Multifiber ARNA recordings were performed in male and female Sprague-Dawley rats (250-400 g) and compared across decerebrate versus Inactin, isoflurane, and urethane anesthesia groups. Intrarenal artery infusion of capsaicin (0.1-50.0 μM, 0.05 mL) produced concentration-dependent increases in ARNA; however, the ARNA sensitivity was significantly greater in decerebrate versus Inactin, isoflurane, and urethane groups. Increases in renal pelvic pressure (0-30 mmHg, 30 s) produced pressure-dependent increases in ARNA; however, ARNA sensitivity was again greater in decerebrate and Inactin groups versus isoflurane and urethane. Acute renal artery occlusion (30 s) increased ARNA, but responses did not differ across groups. Analysis of ARNA responses to increased pelvic pressure between male and female rats revealed significant sex differences only in isoflurane and urethane groups. ARNA responses to intrarenal capsaicin infusion were significantly blunted at nighttime versus daytime; however, ARNA responses to increased pelvic pressure or renal artery occlusion were not different between daytime and nighttime. These results demonstrate that ARNA sensitivity is greatest in decerebrate and Inactin-anesthetized groups but was not consistently influenced by sex.NEW & NOTEWORTHY We determined the impact of anesthesia, sex, and circadian cycle on renal afferent nerve (ARNA) sensitivity to chemical and mechanical stimuli. ARNA sensitivity to renal capsaicin infusion was greatest in decerebrate > Inactin > urethane or isoflurane groups. Elevated renal pelvic pressure significantly increased ARNA; decerebrate and Inactin groups exhibited the greatest ARNA sensitivity. Sex differences in renal afferent responses were not consistently observed. Circadian cycle altered chemosensory but not mechanosensory responses.
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Affiliation(s)
- Leon J DeLalio
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Sean D Stocker
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
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Chen HH, Chu CH, Wen SW, Lai CC, Cheng PW, Tseng CJ. Excessive Fructose Intake Impairs Baroreflex Sensitivity and Led to Elevated Blood Pressure in Rats. Nutrients 2019; 11:nu11112581. [PMID: 31731536 PMCID: PMC6893539 DOI: 10.3390/nu11112581] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 10/21/2019] [Accepted: 10/24/2019] [Indexed: 12/14/2022] Open
Abstract
Hypertension development with an increased intake of added sugar, especially excessive fructose intake, was shown in the National Health and Nutrition Examination Survey (NHANES) data. However, the mechanism underlying blood pressure (BP) elevation with increased fructose intake is still unclear. First, the present study showed that in rats fed 10% fructose for one week, BP and fructose/glucose levels increased in the central and peripheral nervous system. Furthermore, increased fructose intake resulted in an upregulation of fructose concentration in the cerebrospinal fluid. Second, consumption of excess fructose increased serum triglycerides. However, the inhibition of triglyceride production did not mitigate sympathetic nerve hyperactivity, but contributed to an insignificant decrease in BP. Finally, increased fructose intake reduced nitric oxide (NO) levels in the nucleus tractus solitarii (NTS) and reduced baroreflex sensitivity within a week. Collectively, the data suggested that fructose intake reduced NO levels in the NTS and caused baroreflex dysfunction, which further stimulated sympathetic nerve activity and induced the development of high BP.
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Affiliation(s)
- Hsin-Hung Chen
- Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung 813, Taiwan, (H.-H.C.)
- Yuh-Ing Junior College of Health Care & Management, Kaohsiung 821, Taiwan
| | - Chih-Hsun Chu
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kaohsiung Veterans General Hospital, Kaohsiung 813, Taiwan,
- Department of Nursing, Fooyin University, Kaohsiung 831, Taiwan
| | - Shu-Wei Wen
- Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung 813, Taiwan, (H.-H.C.)
| | - Chi-Cheng Lai
- Cardiology, Kaohsiung Municipal United Hospital, Kaohsiung 804, Taiwan,
| | - Pei-Wen Cheng
- Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung 813, Taiwan, (H.-H.C.)
- Institute of Biomedical Sciences, National Sun Yat-sen University, Kaohsiung 804, Taiwan
| | - Ching-Jiunn Tseng
- Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung 813, Taiwan, (H.-H.C.)
- Institute of Biomedical Sciences, National Sun Yat-sen University, Kaohsiung 804, Taiwan
- Department of Pharmacology, National Defense Medical Center, Taipei 114, Taiwan
- Department of Medical Research, China Medical University Hospital, China Medical University, Taichung 404, Taiwan
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Barman SM, Yates BJ. Deciphering the Neural Control of Sympathetic Nerve Activity: Status Report and Directions for Future Research. Front Neurosci 2017; 11:730. [PMID: 29311801 PMCID: PMC5743742 DOI: 10.3389/fnins.2017.00730] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 12/14/2017] [Indexed: 12/15/2022] Open
Abstract
Sympathetic nerve activity (SNA) contributes appreciably to the control of physiological function, such that pathological alterations in SNA can lead to a variety of diseases. The goal of this review is to discuss the characteristics of SNA, briefly review the methodology that has been used to assess SNA and its control, and to describe the essential role of neurophysiological studies in conscious animals to provide additional insights into the regulation of SNA. Studies in both humans and animals have shown that SNA is rhythmic or organized into bursts whose frequency varies depending on experimental conditions and the species. These rhythms are generated by brainstem neurons, and conveyed to sympathetic preganglionic neurons through several pathways, including those emanating from the rostral ventrolateral medulla. Although rhythmic SNA is present in decerebrate animals (indicating that neurons in the brainstem and spinal cord are adequate to generate this activity), there is considerable evidence that a variety of supratentorial structures including the insular and prefrontal cortices, amygdala, and hypothalamic subnuclei provide inputs to the brainstem regions that regulate SNA. It is also known that the characteristics of SNA are altered during stress and particular behaviors such as the defense response and exercise. While it is a certainty that supratentorial structures contribute to changes in SNA during these behaviors, the neural underpinnings of the responses are yet to be established. Understanding how SNA is modified during affective responses and particular behaviors will require neurophysiological studies in awake, behaving animals, including those that entail recording activity from neurons that generate SNA. Recent studies have shown that responses of neurons in the central nervous system to most sensory inputs are context-specific. Future neurophysiological studies in conscious animals should also ascertain whether this general rule also applies to sensory signals that modify SNA.
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Affiliation(s)
- Susan M Barman
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, United States
| | - Bill J Yates
- Department of Otolaryngology, University of Pittsburgh, Pittsburgh, PA, United States.,Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, United States
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Burke SL, Lukoshkova EV, Head GA. Characteristics of renal sympathetic nerve single units in rabbits with angiotensin-induced hypertension. Exp Physiol 2015; 101:50-66. [PMID: 26467849 DOI: 10.1113/ep085472] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 10/06/2015] [Indexed: 11/08/2022]
Abstract
We examined the effect of chronic angiotensin (Ang II)-induced hypertension on activity of postganglionic renal sympathetic units to determine whether altered whole renal nerve activity is due to recruitment or changes in firing frequency. Rabbits were treated with a low (20 ng kg(-1) min(-1), 8 weeks) or high dose (50 ng kg(-1) min(-1), 4 weeks) of Ang II before the experiment under chloralose-urethane anaesthesia. Spontaneously active units were detected from multiunit recordings using an algorithm that separated units by action potential shape using templates that matched spikes within a prescribed standard deviation. Multiunit sympathetic nerve activity was 40% higher in rabbits treated with low-dose Ang II than in sham (P = 0.012) but not different in high-dose Ang II. Resting firing frequency was similar in sham rabbits (1.00 ± 0.09 spikes s(-1), n = 144) and in those treated with high-dose Ang II (1.10 ± 0.08 spikes s(-1), n = 112) but was lower with low-dose Ang II (0.65 ± 0.08 spikes s(-1), n = 149, P < 0.05). Unit firing rhythmicity was linked to the cardiac cycle and was similar in sham and low-dose Ang II groups but 29-32% lower in rabbits treated with high-dose Ang II (P < 0.001). Cardiac linkage followed a similar pattern during hypoxia. All units showed baroreceptor dependency. Baroreflex gain and range were reduced and curves shifted to the right in Ang II groups. Firing frequency during hypoxia increased by +39% in low-dose Ang II and +82% in shams, but the greatest increase was in the high-dose Ang II group (+103%, P(dose) = 0.001). Responses to hypercapnia were similar in all groups. Increases in sympathetic outflow in hypertension caused by low-dose chronic Ang II administration are due to recruitment of neurons, but high-dose Ang II increases firing frequency in response to chemoreceptor stimuli independently of the arterial baroreceptors.
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Affiliation(s)
- Sandra L Burke
- Neuropharmacology Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Elena V Lukoshkova
- Department of Cardiovascular Regulation, Russian Cardiology Research Centre, Moscow, Russia
| | - Geoffrey A Head
- Neuropharmacology Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia.,Department of Pharmacology, Monash University, Clayton, Victoria, Australia
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Ishii K, Mitsuhiro I, Matsukawa K. Differential contribution of aortic and carotid sinus baroreflexes to control of heart rate and renal sympathetic nerve activity. J Physiol Sci 2015; 65:471-80. [PMID: 26159318 PMCID: PMC10717140 DOI: 10.1007/s12576-015-0387-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 06/15/2015] [Indexed: 10/23/2022]
Abstract
We examined the roles of aortic and carotid sinus baroreceptors in control of heart rate (HR) and renal sympathetic nerve activity (RSNA) in 17 decerebrate rats. The baroreflex curves between the changes in mean arterial blood pressure (MAP) and HR or RSNA in response to intravenous injection of phenylephrine (10-20 μg/kg) or nitroprusside (10 μg/kg) were identified before and following sequential denervation of all four baroafferent nerves. The slope of the MAP-HR curve in the pressor range was decreased (P < 0.05) to 31 ± 7% of the control following denervation of bilateral aortic nerves, whereas it remained substantial (72 ± 10%) following denervation of bilateral carotid sinus nerves. The slope for HR became negligible following complete denervation of all four baroafferent nerves. In contrast, the slope of the MAP-RSNA curve decreased as the sequential baroafferent denervation progressed, irrespective of the denervation order, and it remained well as long as any single baroafferent nerve was intact. The similar influences of sequential baroafferent denervation on the responses of HR and RSNA were observed in the depressor range. Thus, it is likely that aortic and carotid sinus baroreceptors play differential roles in control of HR but they contribute similarly to control of RSNA.
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Affiliation(s)
- Kei Ishii
- Department of Integrative Physiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8551 Japan
| | - Idesako Mitsuhiro
- Department of Integrative Physiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8551 Japan
| | - Kanji Matsukawa
- Department of Integrative Physiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8551 Japan
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Sun L, Tanida M, Wang M, Kuda Y, Kurata Y, Shibamoto T. Effects of anesthetics on the renal sympathetic response to anaphylactic hypotension in rats. PLoS One 2014; 9:e113945. [PMID: 25423366 PMCID: PMC4244183 DOI: 10.1371/journal.pone.0113945] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 10/26/2014] [Indexed: 11/23/2022] Open
Abstract
The autonomic nervous system plays an important role in rat anaphylactic hypotension. It is well known that sympathetic nerve activity and cardiovascular function are affected by anesthetics. However, the effects of different types of anesthesia on the efferent renal sympathetic nerve activity (RSNA) during anaphylactic hypotension remain unknown. Therefore, we determined the renal sympathetic responses to anaphylactic hypotension in anesthetized and conscious rats and the roles of baroreceptors in these responses. Sprague-Dawley rats were randomly allocated to anesthetic groups that were given pentobarbital, urethane, or ketamine-xylazine and to a conscious group. The rats were sensitized using subcutaneously injected ovalbumin. The systemic arterial pressure (SAP), RSNA and heart rate (HR) were measured. The effects of sinoaortic baroreceptor denervation on RSNA during anaphylaxis were determined in pentobarbital-anesthetized and conscious rats. In all of the sensitized rats, the RSNA increased and SAP decreased after antigen injection. At the early phase within 35 min of the antigen injection, the antigen-induced sympathoexcitation in the conscious rats was significantly greater than that in the anesthetized rats. Anaphylactic hypotension was attenuated in the conscious rats compared to the anesthetized rats. The anesthetic-induced suppression of SAP and RSNA was greater in the order ketamine-xylazine >urethane = pentobarbital. Indeed, in the rats treated with ketamine-xylazine, RSNA did not increase until 40 min, and SAP remained at low levels after the antigen injection. The baroreceptor reflex, as evaluated by increases in RSNA and HR in response to the decrease in SAP induced by sodium nitroprusside (SNP), was suppressed in the anesthetized rats compared with the conscious rats. Consistent with this finding, baroreceptor denervation attenuated the excitatory responses of RSNA to anaphylaxis in the conscious rats but not in the pentobarbital-anesthetized rats. RSNA was increased markedly in conscious rats during anaphylactic hypotension. Anesthetics attenuated this antigen-induced renal sympathoexcitation through the suppression of baroreceptor function.
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Affiliation(s)
- Lingling Sun
- Department of Physiology II, Kanazawa Medical University, Uchinada, Ishikawa, Japan
- Department of Hematology, the Fourth Affiliated Hospital of China Medical University, Shenyang, China
| | - Mamoru Tanida
- Department of Physiology II, Kanazawa Medical University, Uchinada, Ishikawa, Japan
| | - Mofei Wang
- Department of Physiology II, Kanazawa Medical University, Uchinada, Ishikawa, Japan
- Department of Colorectal Surgery, the Fourth Affiliated Hospital of China Medical University, Shenyang, China
| | - Yuhichi Kuda
- Department of Physiology II, Kanazawa Medical University, Uchinada, Ishikawa, Japan
| | - Yasutaka Kurata
- Department of Physiology II, Kanazawa Medical University, Uchinada, Ishikawa, Japan
| | - Toshishige Shibamoto
- Department of Physiology II, Kanazawa Medical University, Uchinada, Ishikawa, Japan
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Arnold AC, Sakima A, Kasper SO, Vinsant S, Garcia-Espinosa MA, Diz DI. The brain renin-angiotensin system and cardiovascular responses to stress: insights from transgenic rats with low brain angiotensinogen. J Appl Physiol (1985) 2012; 113:1929-36. [PMID: 22984245 DOI: 10.1152/japplphysiol.00569.2012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The renin-angiotensin system (RAS) has been identified as an attractive target for the treatment of stress-induced cardiovascular disorders. The effects of angiotensin (ANG) peptides during stress responses likely result from an integration of actions by circulating peptides and brain peptides derived from neuronal and glial sources. The present review focuses on the contribution of endogenous brain ANG peptides to pathways involved in cardiovascular responses to stressors. During a variety of forms of stress, neuronal pathways in forebrain areas containing ANG II or ANG-(1-7) are activated to stimulate descending angiotensinergic pathways that increase sympathetic outflow to increase blood pressure. We provide evidence that glia-derived ANG peptides influence brain AT(1) receptors. This appears to result in modulation of the responsiveness of the neuronal pathways activated during stressors that elevate circulating ANG peptides to activate brain pathways involving descending hypothalamic projections. It is well established that increased cardiovascular reactivity to stress is a significant predictor of hypertension and other cardiovascular diseases. This review highlights the importance of understanding the impact of RAS components from the circulation, neurons, and glia on the integration of cardiovascular responses to stressors.
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Affiliation(s)
- Amy C Arnold
- The Hypertension & Vascular Research Center and the Departments of General Surgery and Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157-1032, USA
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Cui F, Gao L, Yuan F, Dong ZF, Zhou ZN, Kline DD, Zhang Y, Li DP. Hypobaric intermittent hypoxia attenuates hypoxia-induced depressor response. PLoS One 2012; 7:e41656. [PMID: 22848558 PMCID: PMC3407201 DOI: 10.1371/journal.pone.0041656] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Accepted: 06/25/2012] [Indexed: 11/17/2022] Open
Abstract
Background Hypobaric intermittent hypoxia (HIH) produces many favorable effects in the cardiovascular system such as anti-hypertensive effect. In this study, we showed that HIH significantly attenuated a depressor response induced by acute hypoxia. Methodology/Principal Findings Sprague-Dawley rats received HIH in a hypobaric chamber simulating an altitude of 5000 m. The artery blood pressure (ABP), heart rate (HR) and renal sympathetic nerve activity (RSNA) were recorded in anesthetized control rats and rats received HIH. The baseline ABP, HR and RSNA were not different between HIH and control rats. Acute hypoxia-induced decrease in ABP was significantly attenuated in HIH rat compared with control rats. However, acute hypoxia-induced increases in HR and RSNA were greater in HIH rat than in control rats. After removal of bilateral ascending depressor nerves, acute hypoxia-induced depressor and sympathoexcitatory responses were comparable in control and HIH rats. Furthermore, acute hypoxia-induced depressor and sympathoexcitatory responses did not differ between control and HIH groups after blocking ATP-dependent K+ channels by glibenclamide. The baroreflex function evaluated by intravenous injection of phenylephrine and sodium nitroprusside was markedly augmented in HIH rats compared with control rats. The pressor and sympathoexcitatory responses evoked by intravenous injection of cyanide potassium were also significantly greater in HIH rats than in control rats. Conclusions/Significance Our findings suggest that HIH suppresses acute hypoxia-induced depressor response through enhancement of baroreflex and chemoreflex function, which involves activation of ATP-dependent K+ channels. This study provides new information and underlying mechanism on the beneficiary effect of HIH on maintaining cardiovascular homeostasis.
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Affiliation(s)
- Fang Cui
- Department of Physiology, Hebei Medical University, Shijiazhuang, China
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Autonomic and cardiovascular effects of pentobarbital anesthesia during trigeminal stimulation in cats. Int J Oral Sci 2012; 4:24-9. [PMID: 22388694 PMCID: PMC3412660 DOI: 10.1038/ijos.2012.7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Stimulation of the trigeminal nerve can elicit various cardiovascular and autonomic responses; however, the effects of anesthesia with pentobarbital sodium on these responses are unclear. Pentobarbital sodium was infused intravenously at a nominal rate and the lingual nerve was electrically stimulated at each infusion rate. Increases in systolic blood pressure (SBP) and heart rate (HR) were evoked by lingual nerve stimulation at an infusion rate between 5 and 7 mg·kg−1·h−1. This response was associated with an increase in the low-frequency band of SBP variability (SBP-LF). As the infusion rate increased to 10 mg·kg−1·h−1 or more, decreases in SBP and HR were observed. This response was associated with the reduction of SBP-LF. In conclusion, lingual nerve stimulation has both sympathomimetic and sympathoinhibitory effects, depending on the depth of pentobarbital anesthesia. The reaction pattern seems to be closely related to the autonomic balance produced by pentobarbital anesthesia.
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Hodges GJ, Jackson DN, Mattar L, Johnson JM, Shoemaker JK. Neuropeptide Y and neurovascular control in skeletal muscle and skin. Am J Physiol Regul Integr Comp Physiol 2009; 297:R546-55. [PMID: 19571208 DOI: 10.1152/ajpregu.00157.2009] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Neuropeptide Y (NPY) is a ubiquitous peptide with multiple effects on energy metabolism, reproduction, neurogenesis, and emotion. In addition, NPY is an important sympathetic neurotransmitter involved in neurovascular regulation. Although early studies suggested that the vasoactive effects of NPY were limited to periods of high stress, there is growing evidence for the involvement of NPY on baseline vasomotor tone and sympathetically evoked vasoconstriction in vivo in both skeletal muscle and the cutaneous circulation. In Sprague-Dawley rat skeletal muscle, Y(1)-receptor activation appears to play an important role in the regulation of basal vascular conductance, and this effect is similar in magnitude to the alpha(1)-receptor contribution. Furthermore, under baseline conditions, agonist and receptor-based mechanisms for Y(1)-receptor-dependent control of vascular conductance in skeletal muscle are greater in male than female rats. In skin, there is Y(1)-receptor-mediated vasoconstriction during whole body, but not local, cooling. As with the NPY system in muscle, this neural effect in skin differs between males and females and in addition, declines with aging. Intriguingly, skin vasodilation to local heating also requires NPY and is currently thought to be acting via a nitric oxide pathway. These studies are establishing further interest in the role of NPY as an important vasoactive agent in muscle and skin, adding to the complexity of neurovascular regulation in these tissues. In this review, we focus on the role of NPY on baseline vasomotor tone in skeletal muscle and skin and how NPY modulates vasomotor tone in response to stress, with the aim of compiling what is currently known, while highlighting some of the more pertinent questions yet to be answered.
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Affiliation(s)
- Gary J Hodges
- School of Kinesiology, University of Western Ontario, London, Ontario.
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Komine H, Matsukawa K, Tsuchimochi H, Nakamoto T, Murata J. Sympathetic cholinergic nerve contributes to increased muscle blood flow at the onset of voluntary static exercise in conscious cats. Am J Physiol Regul Integr Comp Physiol 2008; 295:R1251-62. [PMID: 18703415 DOI: 10.1152/ajpregu.00076.2008] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We examined whether a sympathetic cholinergic mechanism contributed to increased blood flow of the exercising muscle at the onset of voluntary static exercise in conscious cats. After six cats were operantly conditioned to perform static bar press exercise with a forelimb while maintaining a sitting posture, a Transonic or pulsed Doppler flow probe was implanted on the brachial artery of the exercising forelimb, and catheters were inserted into the left carotid artery and jugular vein. After the baseline brachial blood flow and vascular conductance decreased and became stable in progress of postoperative recovery, the static exercise experiments were started. Brachial blood flow and vascular conductance began to increase simultaneously with the onset of exercise. Their initial increases reached 52 +/- 8% and 40 +/- 6% at 3 s from the exercise onset, respectively. Both a sympathetic ganglionic blocker (hexamethonium bromide) and atropine sulfate or methyl nitrate blunted the increase in brachial vascular conductance at the onset of static exercise, whereas an inhibitor of nitric oxide synthesis (N(omega)-nitro-l-arginine methyl ester) did not alter the increase in brachial vascular resistance. Brachial blood flow and vascular conductance increased during natural grooming behavior with the forelimb in which the flow probe was implanted, whereas they decreased during grooming with the opposite forelimb and during eating behavior. Thus it is likely that the sympathetic cholinergic mechanism is capable of evoking muscle vasodilatation at the onset of voluntary static exercise in conscious cats.
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Affiliation(s)
- Hidehiko Komine
- Dept. of Physiology, Graduate School of Health Sciences, Hiroshima Univ., Kasumi 1-2-3, Minami-ku, Hiroshima 734-8551, Japan
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Caligiorne SM, Silva AQG, Fontes MAP, Silva JR, Baltatu O, Bader M, Santos RAS, Campagnole-Santos MJ. Baroreflex control of heart rate and renal sympathetic nerve activity in rats with low brain angiotensinogen. Neuropeptides 2008; 42:159-68. [PMID: 18242696 DOI: 10.1016/j.npep.2007.12.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2007] [Revised: 12/13/2007] [Accepted: 12/15/2007] [Indexed: 01/30/2023]
Abstract
The main objective of the present study was to evaluate baroreceptor control of heart rate (HR) and renal sympathetic nerve activity (RSNA) in transgenic rats (TG) with low angiotensinogen production in glial cells, TGR(ASrAogen)-680. In addition, the sympathetic and vagal autonomic tonus to the heart was investigated. As previously shown, TG rats presented a lower arterial pressure (AP) and HR. However, TG rats had decreased AP variability during the night (8.9+/-0.4 mmHg vs 9.8+/-0.3 mmHg, in SD) accompanied by an increase in HR variability (39+/-1 beats/min vs 35+/-1 beats/min, in SD) and augmented locomotor activity during the night (3.5+/-0.3 counts/min vs 2.5+/-0.2 counts/min, in SD). In addition, TG rats presented increased baroreflex sensitivity for the RSNA (slope of line that correlates decreases in RSNA and increases in AP=1.36+/-0.18 vs 0.77+/-0.1, in SD) and an increased sensitivity for both the baroreflex bradycardia (0.79+/-0.04 ms/mmHg vs 0.52+/-0.04 ms/mmHg, in SD) and tachycardia (1.46+/-0.1 ms/mmHg vs 0.93+/-0.01 ms/mmHg, in SD). Further, TG rats had increased vagal tonus (25+/-3 beats/min vs 11+/-4 beats/min in SD) without significant change in the sympathetic tonus to the heart. These results confirm and extend previous observations showing that glial angiotensinogen, the main source of brain RAS peptides, importantly modulates sympathetic tonus, at least to the renal nerve, and vagal tonus to the heart.
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Affiliation(s)
- Sordaini M Caligiorne
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av Antonio Carlos, 6627-ICB, 31270-901 Belo Horizonte, MG, Brazil
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Zhang ZH, Yu Y, Kang YM, Wei SG, Felder RB. Aldosterone acts centrally to increase brain renin-angiotensin system activity and oxidative stress in normal rats. Am J Physiol Heart Circ Physiol 2008; 294:H1067-74. [DOI: 10.1152/ajpheart.01131.2007] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Aldosterone acts upon mineralocorticoid receptors in the brain to increase blood pressure and sympathetic nerve activity, but the mechanisms are still poorly understood. We hypothesized that aldosterone increases sympathetic nerve activity by upregulating the renin-angiotensin system (RAS) and oxidative stress in the brain, as it does in peripheral tissues. In Sprague-Dawley rats, aldosterone (Aldo) or vehicle (Veh) was infused for 1 wk via an intracerebroventricular (ICV) cannula, while RU-28318 (selective mineralocorticoid receptor antagonist), Tempol (superoxide dismutase mimetic), losartan [angiotensin II type 1 receptor (AT1R) antagonist], or Veh was infused simultaneously via a second ICV cannula. After 1 wk of ICV Aldo, plasma norepinephrine was increased and mean arterial pressure was slightly elevated, but heart rate was unchanged. These effects were ameliorated by ICV infusion of RU-28318, Tempol or losartan. Aldo increased expression of AT1R and angiotensin-converting enzyme (ACE) mRNA in hypothalamic tissue. RU-28318 minimized and Tempol prevented the increase in AT1R mRNA; RU-28318 prevented the increase in ACE mRNA. Losartan had no effect on AT1R or ACE mRNA. Immunohistochemistry revealed Aldo-induced increases in dihydroethidium staining (indicating oxidative stress) and Fra-like activity (indicating neuronal excitation) in neurons of the hypothalamic paraventricular nucleus (PVN). RU-28318 prevented the increases in superoxide and Fra-like activity in PVN; Tempol and losartan minimized these effects. Acute ICV infusions of sarthran (AT1R antagonist) or Tempol produced greater sympathoinhibition in Aldo-treated than in Veh-treated rats. Thus aldosterone upregulates key elements of brain RAS and induces oxidative stress in the hypothalamus. Aldosterone may increase sympathetic nerve activity by these mechanisms.
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Matsukawa K, Nakamoto T. Muscle mechanosensitive reflex is suppressed in the conscious condition: effect of anesthesia. J Appl Physiol (1985) 2007; 104:82-7. [PMID: 17962571 DOI: 10.1152/japplphysiol.00938.2007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To test the hypothesis that a muscle mechanosensitive reflex is suppressed in the conscious condition, we examined the effect of anesthesia on the cardiovascular responses to passive mechanical stretch of the hindlimb triceps surae muscle in six conscious cats. The triceps surae muscle was manually stretched for 30 s by extending the hip and knee joints and subsequently by dorsiflexing the ankle joint; the lateral gastrocnemius muscle was lengthened by 19 +/- 2.6 mm. Heart rate (HR) and mean arterial blood pressure (MAP) did not change significantly during passive stretch of the muscle in the conscious condition. At 10-40 min after intravenously administering pentobarbital sodium (20-25 mg/kg), the identical passive stretch of the triceps surae muscle was able to induce the cardiovascular responses; HR and MAP were increased by 14 +/- 1.3 beats/min and 14 +/- 1.4 mmHg, respectively, and the cardiovascular responses were sustained throughout the passive stretch. In contrast, stretching skin on the triceps surae muscle evoked no significant changes in HR and MAP in the anesthetized condition. When anesthesia became light 40-90 min after injection of pentobarbital and the animals started to show spontaneous body movement, the cardiovascular response to passive muscle stretch tended to be blunted again. It is therefore concluded that passive mechanical stretch of skeletal muscle is capable of evoking the reflex cardiovascular response, which is suppressed in the conscious condition but exaggerated by anesthesia.
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Affiliation(s)
- Kanji Matsukawa
- Dept. of Physiology, Graduate School of Health Sciences, Hiroshima Univ., Kasumi 1-2-3, Minami-ku Hiroshima 734-8551, Japan.
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Sakima A, Averill DB, Kasper SO, Jackson L, Ganten D, Ferrario CM, Gallagher PE, Diz DI. Baroreceptor reflex regulation in anesthetized transgenic rats with low glia-derived angiotensinogen. Am J Physiol Heart Circ Physiol 2006; 292:H1412-9. [PMID: 17085537 DOI: 10.1152/ajpheart.00984.2006] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Endogenous angiotensin (ANG) II and ANG-(1-7) act at the nucleus tractus solitarius (NTS) to differentially modulate neural control of the circulation. The role of these peptides endogenous to NTS on cardiovascular reflex function was investigated in transgenic rats with low brain angiotensinogen (Aogen) due to glial overexpression of an antisense to Aogen (ASrAOGEN) and in Sprague-Dawley (SD) rats. Arterial baroreceptor reflex sensitivity (BRS) for control of heart rate (HR) in response to increases in mean arterial pressure (MAP) was tested before and after bilateral microinjection of the angiotensin type 1 (AT(1)) receptor blocker candesartan or the ANG-(1-7) receptor blocker (d-Ala(7))-ANG-(1-7) into the NTS of urethane-chloralose-anesthetized ASrAOGEN and SD rats. Baseline MAP was higher in ASrAOGEN than in SD rats under anesthesia (P < 0.01). Injection of candesartan or (d-Ala(7))-ANG-(1-7) decreased MAP (P < 0.01) and HR (P < 0.05) in ASrAOGEN, but not SD, rats. The BRS at baseline was similar in ASrAOGEN and SD rats. Candesartan increased BRS by 41% in SD rats (P < 0.01) but was without effect in ASrAOGEN rats. In contrast, the reduction in BRS after (d-Ala(7))-ANG-(1-7) administration was comparable in SD (31%) and ASrAOGEN rats (34%). These findings indicate that the absence of glia-derived Aogen is associated with 1) an increase in MAP under anesthesia mediated via AT(1) and ANG-(1-7) receptors within the NTS, 2) the absence of an endogenous ANG II contribution to tonic inhibition of BRS, and 3) a continued contribution of endogenous ANG-(1-7) to tonic enhancement of BRS.
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Affiliation(s)
- Atsushi Sakima
- Hypertension & Vascular Disease Center, Wake Forest Univ School of Medicine, Winston-Salem, NC 27157-1032, USA
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17
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Jackson DN, Noble EG, Shoemaker JK. Y1- and alpha1-receptor control of basal hindlimb vascular tone. Am J Physiol Regul Integr Comp Physiol 2004; 287:R228-33. [PMID: 15044188 DOI: 10.1152/ajpregu.00723.2003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The role of endogenous Y(1)-receptor activation on skeletal muscle vasculature under baseline conditions is currently debated and no in vivo studies have been performed to address this issue. Therefore, this study was designed to address the effect of Y(1)-receptor and/or alpha(1)-adrenoceptor antagonism on basal hindlimb vascular conductance in male Sprague-Dawley rats in vivo. Left hindlimb vascular conductance, carotid artery mean arterial pressure, and heart rate were measured during low volume infusion of N(2)-(diphenylacetyl)-N-[(4-hydroxyphenyl)methyl]-d-arginine amide (BIBP3226; 100 microg/kg), prazosin (20 microg/kg), and combined blockade to the left hindlimb. Vascular conductance increased 1.5 +/- 0.5 microl.min(-1).mmHg(-1) with BIBP3226 infusion, 1.7 +/- 0.5 microl.min(-1).mmHg(-1) with prazosin infusion, and 4.8 +/- 1.0 microl.min(-1).mmHg(-1) with combined blockade (P < 0.05). Interestingly, systolic vascular conductance increased in all three conditions, but diastolic vascular conductance only increased in the two conditions where BIBP3226 was present. These data indicate that Y(1)-receptor activation plays an important role in the regulation of vascular conductance in the resting rat hindlimb. Furthermore, this effect was of the same magnitude as the alpha(1)-adrenoceptor contribution. The differential flow profiles following alpha(1) blockade with and without Y(1)-receptor blockade supports local differences in receptor distribution.
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Affiliation(s)
- Dwayne N Jackson
- Neurovascular Research Laboratory, School of Kinesiology, Rm. 3110, Thames Hall, Univ. of Western Ontario, London, Ontario, Canada
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Mutoh T, Shibata S, Korf HW, Okamura H. Melatonin modulates the light-induced sympathoexcitation and vagal suppression with participation of the suprachiasmatic nucleus in mice. J Physiol 2003; 547:317-32. [PMID: 12562939 PMCID: PMC2342619 DOI: 10.1113/jphysiol.2002.028001] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 07/05/2002] [Accepted: 12/03/2002] [Indexed: 12/15/2022] Open
Abstract
In mammals, the autonomic nervous system mediates the central circadian clock oscillation from the suprachiasmatic nucleus (SCN) to the peripheral organs, and controls cardiovascular, respiratory and gastrointestinal functions. The present study was conducted in mice to address whether light signals conveyed to the SCN can control peripheral autonomic functions, and further examined the impact of centrally administered melatonin on peripheral autonomic functions via activation of melatonin receptor signalling. In vivo electrophysiological techniques were performed in anaesthetised, open-chest and artificially ventilated mice whilst monitoring the arterial blood pressure and heart rate. Light induced an increase of the renal sympathetic nerve activity, arterial blood pressure and heart rate immediately after lights on. Conversely, light rapidly suppressed the gastric vagal parasympathetic nerve activity, which was affected neither by hepatic vagotomy nor by total subdiaphragmatic vagotomy. These autonomic responses were mediated by the SCN since bilateral SCN lesion totally abolished the light-evoked neuronal and cardiovascular responses. Melatonin administered intracerebroventricularly (I.C.V.) attenuated the sympathetic and vagal nerve activities in a dose-dependent manner with a threshold of 0.1 ng and these effects were blocked by I.C.V. pre-treatment of the competitive melatonin receptor antagonist luzindole. These results suggest that light induces sympathoexcitation and vagal suppression through the SCN and that melatonin modulates the light-induced autonomic responses via activation of the central melatonin receptor signalling.
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Affiliation(s)
- Tatsushi Mutoh
- Division of Molecular Brain Science, Department of Brain Sciences, Kobe University Graduate School of Medicine, Chuo-ku, Kobe 650-0017, Japan
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Jin QH, Ueda Y, Ishizuka Y, Kunitake T, Kannan H. Cardiovascular changes induced by central hypertonic saline are accompanied by glutamate release in awake rats. Am J Physiol Regul Integr Comp Physiol 2001; 281:R1224-31. [PMID: 11557631 DOI: 10.1152/ajpregu.2001.281.4.r1224] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To elucidate neurochemical mechanisms responsible for cardiovascular responses induced by central salt loading, we directly perfused the paraventricular nucleus (PVN) of the hypothalamus region with hypertonic saline (0.3 or 0.45 M) by using an in vivo brain microdialysis technique. We then measured the extracellular concentrations of glutamate in the PVN region in conscious rats along with the blood pressure and heart rate. Blood pressure, heart rate, and glutamate levels were increased by perfusion of 0.45 M saline; however, they did not change by perfusion of 0.3 M saline. Next, we examined the possible involvement of glutamate in the cardiovascular responses induced by hypertonic saline. Dizocilpine, a noncompetitive antagonist of the N-methyl-D-aspartate (NMDA) receptor, attenuated the increases of blood pressure and heart rate, although 6-cyano-7-nitroquinoxaline-2,3-dione, an antagonist of the non-NMDA receptor, did not affect the blood pressure and heart rate. Our results show that local perfusion of the hypothalamic PVN region with hypertonic saline elicits a local release of glutamate, which may act via NMDA-type glutamate receptors to produce cardiovascular responses.
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Affiliation(s)
- Q H Jin
- Department of Physiology, Miyazaki Medical College, Miyazaki 889 - 1692, Japan
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20
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Morales T, Shapiro E, Mena F. beta-adrenergic mechanisms modulate central nervous system effects of prolactin on milk ejection. Physiol Behav 2001; 74:119-26. [PMID: 11564459 DOI: 10.1016/s0031-9384(01)00560-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It is known that prolactin (PRL) is produced within the brain and numerous central actions of the hormone have been reported. In anesthetized lactating rats, central administration of PRL, i.e., intracerebroventricular (icv) or intrathecally (it), facilitated milk ejection (ME) by depressing the sympathetically mediated facilitatory tone of the mammary ductal system. However, it is not known whether or not the same effects and similar mechanisms take place in conscious rats after PRL administration. In the present study, the effects of centrally administered PRL, i.e., icv or it, on ME was determined in both conscious and anesthetized rats. In conscious rats, the rate of ME was determined by applying a 15-min period of suckling by the litter, following a 6-h period of isolation. In anesthetized rats, intramammary pressure (IMP) responses of the mammary glands to exogenous oxytocin (OT) were recorded. The results showed that, whereas in anesthetized rats, increased responsiveness of the mammary glands to OT were observed after PRL administration, an intense inhibition of ME occurred in conscious rats. Because, in conscious and anesthetized rats, these effects were prevented by prior administration of the beta-adrenergic blocker propranolol (PROP) to the mothers, this suggests that the PRL effects on ME are modulated through sympathomimetic and sympatholytic actions in conscious and anesthetized rats, respectively. Thus, as shown by ductal tone measurements, in conscious, but not in anesthetized rats, the effect of PRL was associated with increased ductal constriction within the mammary glands; an effect that was mimicked by icv administration of the beta-adrenergic agonist isoproterenol (ISOP) and that was prevented by PROP. Further, the sympatholytic action of icv-PRL in anesthetized rats prevented the effect on ductal tone of both icv-PRL in conscious rats and of ISOP in anesthetized rats. Taken together, these results clearly suggest that the central effects of PRL on ME are modulated by adrenergic mechanisms.
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Affiliation(s)
- T Morales
- Centro de Neurobiología, Universidad Nacional Autónoma de México, Campus UNAM-UAQ, 76230, Juriquilla, Qro., Mexico
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Matsumura K, Tsuchihashi T, Abe I. Central orexin-A augments sympathoadrenal outflow in conscious rabbits. Hypertension 2001; 37:1382-7. [PMID: 11408381 DOI: 10.1161/01.hyp.37.6.1382] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We determined the cardiovascular and neurohormonal responses to intracerebroventricular administration of orexin-A in conscious rabbits. Intracerebroventricular injection of orexin-A elicited dose-related increases in mean arterial pressure and renal sympathetic nerve activity. Peak values of mean arterial pressure and renal sympathetic nerve activity induced by intracerebroventricular injection of 100 pmol of orexin-A (14.0+/-0.7 mm Hg and 55.4+/-14.9%, respectively) were obtained at 40 and 25 minutes after injection, respectively. Plasma epinephrine and glucose concentrations were significantly increased at 60 and 90 minutes after intracerebroventricular injection of orexin-A (control versus 90 minutes; for epinephrine, 38.0+/-12.8 versus 167.5+/-42.5 pg/mL, P<0.01; for glucose, 6.66+/-0.18 versus 7.75+/-0.14 mmol/L, P<0.01). Plasma norepinephrine and insulin concentrations increased at 60 and 90 minutes but did not attain significant values. Intracerebroventricular injection of orexin-A also caused significant increases in plasma vasopressin concentrations. However, pretreatment with an intravenous injection of pentolinium (5 mg/kg), a ganglion-blocking agent, abolished these cardiovascular and neurohormonal responses. On the other hand, intravenous injection of the same dose of orexin-A (100 pmol) used in the intracerebroventricular experiment failed to cause any cardiovascular and renal sympathetic nerve responses. These results suggest that intracerebroventricular orexin-A acts in the central nervous system and activates sympathoadrenal outflow, resulting in increases in arterial pressure and plasma glucose levels in conscious rabbits.
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Affiliation(s)
- K Matsumura
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
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Matsumura K, Abe I, Tsuchihashi T, Fujishima M. Central effects of leptin on cardiovascular and neurohormonal responses in conscious rabbits. Am J Physiol Regul Integr Comp Physiol 2000; 278:R1314-20. [PMID: 10801302 DOI: 10.1152/ajpregu.2000.278.5.r1314] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We determined the cardiovascular and neurohormonal responses to intracerebroventricular injection of leptin in conscious rabbits. Intracerebroventricular injection of leptin elicited dose-related increases in mean arterial pressure and renal sympathetic nerve activity while producing no consistent, significant increases in heart rate. Peak values of mean arterial pressure and renal sympathetic nerve activity induced by intracerebroventricular injection of 50 microgram of leptin (+17.3 +/- 1.2 mmHg and +47.9 +/- 12.0%) were obtained at 10 and 20 min after injection, respectively. Plasma catecholamine concentrations significantly increased at 60 min after intracerebroventricular injection of leptin (control vs. 60 min; epinephrine: 33 +/- 12 vs. 97 +/- 27 pg/ml, P < 0.05; norepinephrine: 298 +/- 39 vs. 503 +/- 86 pg/ml, P < 0.05). Intracerebroventricular injection of leptin also caused significant increases in plasma vasopressin and glucose levels. However, pretreatment with intravenous injection of pentolinium (5 mg/kg), a ganglion blocking agent, abolished these cardiovascular and neurohormonal responses. On the other hand, intravenous injection of the same dose of leptin (50 microgram) as used in the intracerebroventricular experiment failed to cause any cardiovascular and renal sympathetic nerve responses. These results suggest that intracerebroventricular leptin acts in the central nervous system and activates sympathoadrenal outflow, resulting in increases in arterial pressure and plasma glucose levels in conscious rabbits.
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Affiliation(s)
- K Matsumura
- Second Department of Internal Medicine, Faculty of Medicine, Kyushu University, Fukuoka 812-8582, Japan.
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Toda K, Tatsumi E, Taenaka Y, Masuzawa T, Takano H. Impact of systemic depulsation on tissue perfusion and sympathetic nerve activity. Ann Thorac Surg 1996; 62:1737-42. [PMID: 8957379 DOI: 10.1016/s0003-4975(96)00568-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND We postulated that pathophysiologic processes under nonpulsatile circulation are related to the behavior of the sympathetic nerve activity that regulates tissue perfusion. METHODS Pulsatile and nonpulsatile pumps were installed in parallel in the left heart bypass circuit of anesthetized goats (n = 9) so that pulsatile circulation could be converted to nonpulsatile circulation instantly. At 5 minutes before and after systemic depulsation, we measured hemodynamic indices, renal nerve activity, and regional blood flow of the brain, heart, and renal cortex. RESULTS Renal nerve activity was significantly elevated after systemic depulsation (15.6 +/- 9.3 versus 19.4 +/- 9.8 microV), when mean aortic pressure remained almost constant. The renal cortical flow was significantly reduced after depulsation (3.61 +/- 1.23 versus 2.93 +/- 1.19 mL.min-1.g-1), whereas no significant difference was found in the regional blood flow of the brain or the heart. CONCLUSIONS The significant reduction of renal cortical blood flow after systemic depulsation is associated with a significant increase in renal nerve activity. Our results suggest that increased renal nerve activity plays an important role in the reduction of renal function after systemic depulsation.
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Affiliation(s)
- K Toda
- Department of Artificial Organs, National Cardiovascular Center Research Institute, Osaka, Japan
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Sannajust F, Cerutti C, Koenig-Bérard E, Sassard J. Influence of anaesthesia on the cardiovascular effects of rilmenidine and clonidine in spontaneously hypertensive rats. Br J Pharmacol 1992; 105:542-8. [PMID: 1352719 PMCID: PMC1908436 DOI: 10.1111/j.1476-5381.1992.tb09016.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
1. The acute cardiovascular effects of two alpha 2-adrenoceptor agonists, rilmenidine and clonidine, were studied in 15-week-old male spontaneously hypertensive rats (SHRs). The effects of these drugs were compared with intravenous (i.v.) and intracerebroventricular (i.c.v.) administration in conscious and pentobarbitone-anaesthetized SHRs, in which aortic blood pressure (BP) was continuously recorded. 2. In conscious SHRs, i.v. doses of either rilmenidine (30, 100, 300 micrograms kg-1) or clonidine (3, 10, 30 micrograms kg-1) induced dose-dependent short-lasting increases in BP followed by moderate decreases associated with bradycardia, while the same three doses of both drugs given i.c.v. were devoid of BP and heart rate (HR) effects. 3. Pentobarbitone-anaesthesia increased the sympathetic control of BP and suppressed the cardiac baroreflex sensitivity. 4. In anaesthetized SHRs, i.v. injections of the same 3 doses of rilmenidine and clonidine induced a slight increase in BP, rapidly followed by profound and long-lasting BP and HR decreases. Surprisingly, when given i.c.v., these 3 doses lowered BP and HR to the same extent but in a more progressive manner. 5. The lack of efficacy of both drugs in conscious SHRs after the i.c.v. administration of i.v. active doses and the lack of more marked and rapid effects in anaesthetized SHRs, after i.c.v. than after i.v. injections, question the involvement of a major central site of action for these antihypertensive alpha 2-adrenoceptor agonists. Moreover, these results show that the cardiovascular effects of these drugs are profoundly influenced by baseline sympathetic nervous system activity which is enhanced by pentobarbitone-anaesthesia.
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Affiliation(s)
- F Sannajust
- Department of Physiology and Clinical Pharmacology, URA-CNRS 606, Faculty of Pharmacy, Lyon, France
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Sannajust F, Barrès C, Koenig-Bérard E, Sassard J. Sympathoinhibitory effects of rilmenidine may be mediated by sites located below the brainstem. Br J Pharmacol 1992; 105:535-41. [PMID: 1352718 PMCID: PMC1908468 DOI: 10.1111/j.1476-5381.1992.tb09015.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
1. To determine the site of action of rilmenidine, we examined its effets on arterial blood pressure (BP), heart rate (HR) and postganglionic renal sympathetic nerve activity (RSNA) after intracerebroventricular (i.c.v.) administration (300 micrograms kg-1), in groups (all n = 6) of conscious and freely moving, pentobarbitone-anaesthetized and pentobarbitone-anaesthetized and spinally transected, fifteen week-old male spontaneously hypertensive rats (SHRs). 2. In conscious SHRs, which exhibited a low sympathetic nerve activity (RSNA: 3.4 +/- 0.9 muV), rilmenidine was inactive on systolic BP (SBP), diastolic BP (DBP), HR and RSNA. 3. In intact pentobarbitone-anaesthetized SHRs, which exhibited an elevated sympathetic nerve activity (RSNA: 10.6 +/- 0.9 muV), rilmenidine exerted potent antihypertensive (delta SBP: -37 +/- 4%; delta DBP: -43 +/- 6%), bradycardic (delta HR: -32 +/- 3%) and sympathoinhibitory (delta RSNA: -68 +/- 9%) activities. 4. In pentobarbitone-anaesthetized SHRs with cervical spinal cord transection, BP was markedly decreased and sympathetic nerve activity (RSNA: 10.3 +/- 3.1 muV) returned to the level observed in conscious SHRs (RSNA: 3.6 +/- 0.5 muV). In these conditions, rilmenidine remained sympathoinhibitory (delta RSNA: -74 +/- 5%). 5. In conclusion, we have shown that pentobarbitone-anaesthesia enhances the peripheral sympathetic tone by a central action, as the spinal cord transection allows RSNA to return to normal levels and that, spinal or ganglionic structures could be a major site of the sympathoinhibitory action of rilmenidine.
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Affiliation(s)
- F Sannajust
- Department of Physiology and Clinical Pharmacology, URA-CNRS 606, Faculty of Pharmacy, Lyon, France
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Matsukawa K, Mitchell JH, Wall PT, Wilson LB. The effect of static exercise on renal sympathetic nerve activity in conscious cats. J Physiol 1991; 434:453-67. [PMID: 2023126 PMCID: PMC1181428 DOI: 10.1113/jphysiol.1991.sp018480] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
1. Renal sympathetic nerve activity (RNA), heart rate (HR), arterial blood pressure (AP), and force development were measured simultaneously during voluntary static (isometric) exercise performed by conscious cats. The cats were operantly trained to press a bar with one forelimb. When the force applied to the bar exceeded a predetermined value (threshold), a sound was emitted by a buzzer for audio-feedback. If the cat continued to produce the appropriate force for a period of 26-55 s, food was given as a reward. 2. A total of eighty-nine exercise trials were performed by seven cats. The peak force applied to the bar was 468 +/- 28 g (mean +/- S.E.M.). RNA, HR, and AP increased significantly from the control value during static exercise by 102 +/- 14%, 23 +/- 2 beats/min, and 11 +/- 1 mmHg, respectively. 3. The increase in RNA had both an initial and a late component. The initial component occurred at or immediately before the onset of force development and lasted for 10 s, while the late component gradually increased 14 s after the onset of static exercise and was sustained until the exercise was terminated. 4. HR also increased at the beginning of static exercise with a similar time course as RNA. Then, HR returned to the control value and remained at that level during the remainder of exercise. The increase in AP was delayed by 10 s from the initial increase in RNA and then continued to rise throughout the period of exercise. 5. The sound of the buzzer was emitted during rest to determine any influence of anticipation or conditioning on the response. RNA and AP increased slightly, but HR did not change. The increases in RNA and AP were much smaller than the increases obtained during static exercise. Thus, the increases in RNA, HR and AP during static exercise appeared to be associated with the exercise itself and not due to anticipation and/or conditioning. 6. When AP was elevated by a bolus injection of noradrenaline, RNA during rest was almost abolished and the increase of RNA during static exercise was markedly inhibited. Thus the arterial baroreflex significantly influences RNA both during rest and during static exercise. 7. This study suggests that the initial increases in RNA and HR at the beginning of static exercise in conscious cats are caused by descending input from higher brain centres and not by afferent feedback signals from muscle receptors or by arterial baroreceptors.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- K Matsukawa
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas 75235
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