Vascular tone and angiogenesis modulation by catecholamine coordinated to ruthenium

Catecholamines participate in angiogenesis, an important tumor development process. However, the way catecholamines interact with their receptors has not been completely elucidated, and doubts still remain as to whether these interactions occur between catechol and/or amine sites and particular amino acid residues on the catecholamine receptors. To evaluate how catechol and amine groups contribute to angiogenesis, we immobilized the catechol site through ruthenium ion (Ru) coordination, to obtain species with the general formula [Ru(NH₃)₄(catecholamine-R)]Cl. We then assessed the angiogenic activity of the complexes in a chorioallantoic membrane model (CAM) and examined vascular reactivity and calcium mobilization in rat aortas and vascular cells. [Ru(NH₃)₄(catecholamine-R)]Cl acted as partial agonists and/or antagonists of their respective receptors and induced calcium mobilization. [Ru(NH₃)₄(isoproterenol)]⁺ [Ru(NH₃)₄(noradrenaline)]⁺, and [Ru(NH₃)₄(adrenaline)]⁺ behaved as antiangiogenic complexes, whereas [Ru(NH₃)₄(dopamine)]⁺ proved to be a proangiogenic complex. In conclusion, catecholamines and [Ru(NH₃)₄(catecholamine-R)]Cl can modulate angiogenesis, and catechol group availability can modify the way these complexes impact the vascular tone, suggesting that catecholamines and their receptors interact differently after catecholamine coordination to ruthenium.

Chemerin receptor blockade improves vascular function in diabetic obese mice via redox-sensitive and Akt-dependent pathways

Chemerin and its G protein-coupled receptor [chemerin receptor 23 (ChemR23)] have been associated with endothelial dysfunction, inflammation, and insulin resistance. However, the role of chemerin on insulin signaling in the vasculature is still unknown. We aimed to determine whether chemerin reduces vascular insulin signaling and whether there is interplay between chemerin/ChemR23, insulin resistance, and vascular complications associated with type 2 diabetes (T2D). Molecular and vascular mechanisms were probed in mesenteric arteries and cultured vascular smooth muscle cells (VSMCs) from C57BL/6J, nondiabetic lean db/m, and diabetic obese db/db mice as well as in human microvascular endothelial cells (HMECs). Chemerin decreased insulin-induced vasodilatation in C57BL/6J mice, an effect prevented by CCX832 (ChemR23 antagonist) treatment. In VSMCs, chemerin, via oxidative stress- and ChemR23-dependent mechanisms, decreased insulin-induced Akt phosphorylation, glucose transporter 4 translocation to the membrane, and glucose uptake. In HMECs, chemerin decreased insulin-activated nitric oxide signaling. AMP-activated protein kinase phosphorylation was reduced by chemerin in both HMECs and VSMCs. CCX832 treatment of db/db mice decreased body weight, insulin, and glucose levels as well as vascular oxidative stress. CCX832 also partially restored vascular insulin responses in db/db and high-fat diet-fed mice. Our novel in vivo findings highlight chemerin/ChemR23 as a promising therapeutic target to limit insulin resistance and vascular complications associated with obesity-related diabetes. NEW & NOTEWORTHY Our novel findings show that the chemerin/chemerin receptor 23 axis plays a critical role in diabetes-associated vascular oxidative stress and altered insulin signaling. Targeting chemerin/chemerin receptor 23 may be an attractive strategy to improve insulin signaling and vascular function in obesity-associated diabetes.

Pseudomyxoma peritonei: a clinical case of this poorly understood condition

BACKGROUND

Pseudomyxoma peritonei is an uncommon condition with an estimated incidence of one to two per million (worldwide) per year. It is characterized by the peritoneal deposition of mucinous tumors, most commonly of the appendix, and occasionally from the ovary, coupled by mucinous ascites.

CASE PRESENTATION

We report the case of a 76-year-old woman who presented with increased abdominal girth and dyspnea for 2 weeks. She was diagnosed as a case of pseudomyxoma peritonei. She was submitted to right oophorectomy, omentectomy, and pseudomyxoma debulking. The histology was compatible with a mucinous tumor of colorectal/appendicular origin. Chemotherapy was not administered because of her functional status. Two years and 8 months later, she refers with postprandial fullness and has moderate ascites.

Cross-talk with β2 -adrenoceptors enhances ligand affinity properties from endothelial alpha1 D -adrenoceptors that mediates carotid relaxation

OBJECTIVES

Our main objectives were to investigate the affinity properties of endothelial and muscular α1D -adrenoceptors and to characterize the cross-talk between endothelial α1D -adrenoceptors and β2 -adrenoceptors in rat carotid.

METHODS

Relaxation and contraction concentration-response curves for phenylephrine (α1 -adrenergic agonist) were obtained in carotid rings in absence or presence of increasing concentrations of BMY7378 (α1D -adrenergic antagonist), combined or not with increasing concentration of ICI-118,551 (β2 -adrenergic antagonist). Schild analysis was used to estimate the affinity constant from pA2 values of BMY7378.

KEY FINDINGS

BMY7378 produced an unsurmountable antagonism on phenylephrine-induced relaxation but a surmountable antagonism on phenylephrine-induced contraction. BMY7378 potency was higher in inhibiting the relaxation than the contraction induced by phenylephrine because the rightward shifts induced by BMY7378 were greater in the relaxation. The apparent pA2 value for BMY7378 in phenylephrine-induced relaxation was greater than in contraction. When combined with ICI-118,551, BMY7378 yielded a surmountable antagonism on phenylephrine-induced relaxation and presented a pA2 value similar to that obtained in phenylephrine-induced contraction.

CONCLUSIONS

Endothelial α1D -adrenoceptors, which mediates rat carotid relaxation, present high ligand affinity because of the cross-talk with β2 -adrenoceptors, which explains the higher potency of phenylephrine in inducing relaxation than contraction and the atypical unsurmountable antagonism produced by BMY7378 on phenylephrine-induced relaxation.

The role of reactive oxygen species in the modulation of the contraction induced by angiotensin II in carotid artery from diabetic rat

The modulation played by reactive oxygen species on the angiotensin II-induced contraction in type I-diabetic rat carotid was investigated. Concentration-response curves for angiotensin II were obtained in endothelium-intact or endothelium-denuded carotid from control or streptozotocin-induced diabetic rats, pre-treated with tiron (superoxide scavenger), PEG-catalase (hydrogen peroxide scavenger), dimethylthiourea (hydroxyl scavenger), apocynin [NAD(P)H oxidase inhibitor], SC560 (cyclooxygenase-1 inhibitor), SC236 (cyclooxygenase-2 inhibitor) or Y-27632 (Rho-kinase inhibitor). Reactive oxygen species were measured by flow cytometry in dihydroethidium (DHE)-loaded endothelial cells. Cyclooxygenase and AT(1)-receptor expression was assessed by immunohistochemistry. Diabetes increased the angiotensin II-induced contraction but reduced the agonist potency in rat carotid. Endothelium removal, tiron or apocynin restored the angiotensin II-induced contraction in diabetic rat carotid to control levels. PEG-catalase, DMTU or SC560 reduced the angiotensin II-induced contraction in diabetic rat carotid at the same extent. SC236 restored the angiotensin II potency in diabetic rat carotid. Y-27632 reduced the angiotensin II-induced contraction in endothelium-intact or -denuded diabetic rat carotid. Diabetes increased the DHE-fluorescence of carotid endothelial cells. Apocynin reduced the DHE-fluorescence of endothelial cells from diabetic rat carotid to control levels. Diabetes increased the muscular cyclooxygenase-2 expression but reduced the muscular AT(1)-receptor expression in rat carotid. In summary, hydroxyl radical, hydrogen peroxide and superoxide anion-derived from endothelial NAD(P)H oxidase mediate the hyperreactivity to angiotensin II in type I-diabetic rat carotid, involving the participation of cyclooxygenase-1 and Rho-kinase. Moreover, increased muscular cyclooxygenase-2 expression in type I-diabetic rat carotid seems to be related to the local reduced AT(1)-receptor expression and the reduced angiotensin II potency.

Effects of preparation conditions on the characteristics of poly(lactide-co-glycolide) nanospheres loaded with chloro(5,10,15,20-tetraphenylporphyrinato)indium(III)

A 2(4-1) fractional factorial design was utilized to evaluate the influence of four preparation conditions on six characteristics of poly(lactide-co-glycolide) nanospheres loaded with chloro(5,10,15,20-tetraphenylporphyrinato)indium(III). Ethanol in the aqueous phase and the stirring rate were the factors that most influenced the nanosphere characteristics. An increase in these factors caused a decrease in nanosphere size, recovery yield and residual chloroform and an increase in the percent of residual poly(vinyl alcohol). The synergic interaction between these two factors caused an increase in the percent residual chloroform. The entrapment efficiency was increased by an increase of ethanol in the aqueous phase or an increase in the percent poly(vinyl alcohol), but an overall decrease was obtained due to a synergic interaction between these factors. The stirring rate was the only parameter that caused an increase of the zeta potential. Evolutionary operations were then carried out based on the results from the fractional factorial design and nanospheres were obtained with sizes smaller than 200 nm.

Bioética e as diretrizes curriculares nacionais do curso de medicina

O artigo apresenta uma análise dos aspectos bioéticos contidos nas Diretrizes Curriculares Nacionais (DCN) do curso de medicina, documento aprovado em 2001 pelos Ministérios da Educação e da Saúde e que propõe diretrizes para a formação do profissional médico. O campo da Bioética permeia todas as diretivas das DCN do curso de Medicina. Isso credita à disciplina um status de eixo integrador no processo de formação de médicos. Considerando as observações que reforçam a tese de que a sociedade é que conforma a educação, esse novo paradigma contribui para efetivação do sistema de saúde brasileiro, o Sistema Único de Saúde, com todos os nuances e hibridizações de modelos de atenção. A Bioética está legitimada nas DCN. Resta ao aparelho formador garantir que ela se consolide na academia, enquanto ciência propositiva imprescindível para se alcançar a necessária prudência ao conhecimento biológico, associando aos valores humanos a ética da vida.

Relação entre enfermeiros e médicos em hospital escola: a perspectiva dos médicos

O conflito entre profissionais da medicina e da enfermagem, historicamente as duas principais categorias profissionais responsáveis pelo cuidado do paciente, é originado a partir da associação de diversos fatores que vão desde a constituição da equipe multiprofissional até as questões salariais. O presente estudo pretende verificar se, na visão dos médicos, existe conflito na relação entre médicos e enfermeiros no Hospital das Clínicas da Universidade Federal de Goiás (HC/UFG) e quais são os fatores associados. Para tanto, 30 médicos responderam a um questionário com dados demográficos e perguntas em escala Lickert, sobre as variáveis que interferem na relação interprofissional. Dentre os resultados, a média de idade é de 42,7 anos, 50% dos participantes é do sexo feminino e 93,3 dos entrevistados trabalha em outro lugar. A média de anos de trabalho no HC é de 16,3. Quanto às categorias de conflitos se destacam quatro fatores preventivos de conflitos (Pc) com Ranking Médio (RM) maior que 3,0 e dois geradores de conflito (2Gc), quais sejam: Comunicação interprofissional (RM =3,03); Autonomia na equipe (RM=3,63); Relação interprofissional (RM=3,36); Condições de trabalho (RM=2,26); Influência do hospital escola (RM=2,83) e Reflexo no paciente (RM=3,93). Conclui-se que na realidade analisada o conflito é inexistente, por haver uma relação favorável de fatores protetores (4Pc:2Gc), porém o mesmo é iminente, devido à permanência de fatores que podem desencadeá-lo ("Condições de trabalho" e "Influência do hospital-escola"). Além disso, há disputa de poder com a enfermagem, o que pode desequilibrar a situação e gerar problemas éticos.

Aging and total stenosis triggers differential responses of carotid and basilar arteries to endothelin-1 and phenylephrine

Our aim was to investigate the effects of ageing on the vascular contractility of carotid and basilar arteries from guinea-pigs, in a model of total stenosis. Moreover, we attempted to identify whether total stenosis of the left common carotid (stenosed) in adult guinea-pigs, would affect the contractions of contralateral carotid (intact) and basilar arteries to different vasoconstrictors. With this purpose, the left carotid was occluded with a silk thread at a position close to its origin. Vascular reactivity experiments using standard muscle bath were performed 7, 15, 30, and 90 days after carotid occlusion. Reactivity of carotid and basilar arteries to endothelin-1, phenylephrine and KCl was reduced with ageing in naive guinea-pigs. The endothelin-1 and KCl-induced contractions were unaltered in arteries from SHAM-operated animals. Moreover, phenylephrine-induced contractions were reduced in both carotids from 7 days SHAM-operated guinea-pigs, when compared to naive group. Stenosis induced progressive reduction in the contraction induced by endothelin-1, phenylephrine and KCl in the stenosed carotid, when compared to their respective age-matched naive and SHAM groups. Interestingly, an increased contractile-response to vasoconstrictor agents in all the contralateral carotids was observed. Stenosis (30 and 90 days) also induced an increase in the contractions induced by endothelin-1 in the basilar artery. Conversely, phenylephrine and KCl-induced contractions were reduced in basilar arteries 7, 15, 30 and 90 days after stenosis. These results showed that stenosis in adult guinea-pigs induce alterations of vascular reactivity in arteries distant from the site of injury. Thus, in spite of the common use of contralateral carotid as control, it must be aware of the potential alteration induced by stenosis in the vascular motility of such vessels. Additionally, it was verified a relationship between the period of stenosis and the alterations in the vascular reactivity to these vasoconstrictors.

Local TAT-p27Kip1 fusion protein inhibits cell proliferation in rat carotid arteries

INTRODUCTION

p27(Kip1) is a cyclin kinase inhibitor that induces cell cycle arrest. In this study, the efficacy of fusion protein TAT- p27(Kip1) to inhibit cell proliferation in rat perivascular injured carotid arteries was tested.

METHODS

The cDNA of p27(Kip1) and GFP (green fluorescein protein) fused to the TAT epitope, which allows cell penetration, yielded TAT-p27 (Kip1) and TAT-GFP fusion proteins. In vitro biological activity on cell proliferation was evaluated by [(3)H] thymidine DNA incorporation in rabbit aortic endothelial cells (REC). An in vivo model used a silicone collar filled with saline positioned around the carotid vessel for 14 days to produce an increased adventitia cross-sectional area.

RESULTS

TAT-p27(Kip1) inhibited REC proliferation in vitro using either 100, 200, and 500 nM compared to control (88.2 +/- 4.4, 81.3 +/- 7, 71.9 +/- 4.2 vs. 100 +/- 6.7%, N = 3, respectively, p < 0.05). This response was stable for purified proteins stored at -20*C for at least 23 days. In vivo , TAT-p27(Kip1) solution reduced adventitia cross-sectional area in a dose-dependent manner compared to TAT-GFP (area in mm(2) - TAT-p27(Kip1): 200 nM, 0.160 +/- 0.018; 500 nM, 0.050 +/- 0.005 vs. TAT-GFP: 500 nM, 0.595 +/- 0.066 vs. the contralateral: 0.047 +/- 0.005, N = 7, p < 0.01).

CONCLUSION

Taken together, these results provide evidence that TAT-p27(Kip1) can inhibit vascular cells proliferation. It is the first successful demonstration that the cell permeable TAT-p27(Kip1) has potential as a vascular anti-proliferative agent.

5-HT1A/1B, 5-HT6, and 5-HT7 serotonergic receptors recruitment in tonic-clonic seizure-induced antinociception: role of dorsal raphe nucleus

Pharmacological studies have been focused on the involvement of different neural pathways in the organization of antinociception that follows tonic-clonic seizures, including 5-hydroxytryptamine (5-HT)-, norepinephrine-, acetylcholine- and endogenous opioid peptide-mediated mechanisms, giving rise to more in-depth comprehension of this interesting post-ictal antinociceptive phenomenon. The present work investigated the involvement of 5-HT(1A/1B), 5-HT(6), and 5-HT(7) serotonergic receptors through peripheral pretreatment with methiothepin at doses of 0.5, 1.0, 2.0 and 3.0 mg/kg in the organization of the post-ictal antinociception elicited by pharmacologically (with pentylenetetrazole at 64 mg/kg)-induced tonic-clonic seizures. Methiothepin at 1.0 mg/kg blocked the post-ictal antinociception recorded after the end of seizures, whereas doses of 2.0 and 3.0 mg/kg potentiated the post-ictal antinociception. The nociceptive thresholds were kept higher than those of the control group. However, when the same 5-hydroxytryptamine receptors antagonist was microinjected (at 1.0, 3.0 and 5.0 microg/0.2 microL) in the dorsal raphe nucleus, a mesencephalic structure rich in serotonergic neurons and 5-HT receptors, the post-ictal hypo-analgesia was consistently antagonized. The present findings suggest a dual effect of methiothepin, characterized by a disinhibitory effect on the post-ictal antinociception when peripherally administered (possibly due to an antagonism of pre-synaptic 5-HT(1A) serotonergic autoreceptors in the pain endogenous inhibitory system) and an inhibitory effect (possibly due to a DRN post-synaptic 5-HT(1B), 5-HT(6), and 5-HT(7) serotonergic receptors blockade) when centrally administered. The present data also suggest that serotonin-mediated mechanisms of the dorsal raphe nucleus exert a key-role in the modulation of the post-ictal antinociception.

Alpha1D-adrenoceptor-induced relaxation on rat carotid artery is impaired during the endothelial dysfunction evoked in the early stages of hyperhomocysteinemia

Hyperhomocysteinemia is a known risk factor for cardiovascular diseases, but the underlying mechanisms of this pathology are complex. We aimed to evaluate the effect of hyperhomocysteinemia in vasorelaxations induced by alpha(1D)-adrenoceptor agonists. Vascular reactivity of rat carotid artery to the alpha-adrenoceptor agonist, phenylephrine, was enhanced in hyperhomocysteinemia. Mechanical removal of endothelium did not modify the carotid responsiveness to phenylephrine, compared to control. Phenylephrine induces endothelium-dependent relaxation, in the presence of 5-methyl urapidil (alpha(1A)-adrenoceptor antagonist). We hypothesised that endothelial-relaxant alpha(1)-adrenoceptors are impaired by hyperhomocysteinemia. Incubation with prazosin (selective alpha(1)-adrenoceptor antagonist) or BMY7378 (8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4,5]decane-7, 9-dione dihydrochloride) (selective alpha(1D)-adrenoceptor antagonist), similarly inhibited phenylephrine-induced relaxations in both control and hyperhomocysteinemic carotids. Immunohistochemistry showed enhanced immunoreactivity for eNOS and iNOS in hyperhomocysteinemic rats. In carotid arteries from hyperhomocysteinemic rats there was a decrease in superoxide dismutase activity and enhanced superoxide anion production. We conclude that alpha(1D)-adrenoceptors mediate endothelium-dependent relaxation triggered by phenylephrine in rat carotid artery and affect the final tone. Furthermore, the enhanced phenylephrine-induced contraction in carotid artery due to hyperhomocysteinemia is endothelium-dependent and involves a loss of the inhibitory effect of relaxant alpha(1D)-adrenoceptors by reducing NO biodisponibility.

Inhibitory avoidance memory retention in the elevated T-maze is impaired after perivascular manipulation of the common carotid arteries

Perivascular manipulation promoted by the positioning of a silicone collar around the common carotid arteries causes local inflammation and has been suggested as an animal model of atherosclerosis. This manipulation induces biochemical and morphological changes that are similar to those observed in the early stage of atherosclerosis in humans. Based on evidences showing that atherosclerosis is associated with cognitive deficits in humans, we presently investigated the temporal consequences of the bilateral positioning of silicone collars around the common carotid arteries (n = 15) on inhibitory avoidance memory retention in male Wistar rats tested in the elevated T-maze. The effects of this procedure were compared to those observed in sham-operated animals (n = 15) and to those observed in animals submitted to permanent bilateral occlusion of the common carotid arteries (n = 16). Additionally we studied the effects of the pretreatment with the non-selective anti-inflammatory drug indomethacin (n = 13) or the selective COX-2 inhibitor celecoxib (n = 12) and compared the effects to those of the pretreatment with vehicle (n = 11). The results showed that the silicone collar implants induced deficits in memory retention when animals were tested 2 and 4, but not 15 or 30, days after surgery. Permanent bilateral occlusion of the common carotid arteries impaired avoidance retention up to 30 days after surgery. Pretreatment with indomethacin (2 mg/kg/day) or celecoxib (5 mg/kg/day) post surgery and up to 3 days thereafter did not prevent memory deficits caused by silicone collar implants. Our data suggest that the prostanoids that participate in the inflammatory process triggered by the placement of the silicone collar do not seem responsible for the deficit in memory retention observed during the first days after collar placement.

Effects Induced by Tityus serrulatus Scorpion Venom and Its Toxins TsTX-I and TsTX-V on the Rat Isolated Retractor Penis Muscle

The aims of the present study were to investigate the pharmacological effects induced by Tityus serrulatus venom (TsV) and its fractions and to compare with the effects induced by pure alpha (TsTX-V) and beta (TsTX-I) toxins isolated from TsV on rat retractor penis muscle (RPM). TsV, fractions X, XI, XIIa, XIIb (0.01-100 microg/ml) and TsTX-V (1 nmol/l-10 micromol/l) induced concentration-dependent contractions. Prazosin and guanethidine or tetrodotoxin (TTX, 5 micromol/l, 30 min) completely abolished these contractions, suggesting complete dependence on sympathetic nerves. TsV or fractions X, XI, XIIa, XIIb (0.01- 100 microg/ml), TsTX-I and TsTX-V (1 nmol/l-10 micromol/l) induced concentration-dependent relaxations in the precontracted RPM. TTX or N(omega)-nitro-L-arginine methyl ester (L-NAME, 100 micromol/l, 30 min) completely abolished the relaxations. Our results suggest that most of TsV-derivated toxins induce contraction and relaxation on RPM by sympathetic and NANC nitrergic nerve stimulation. Noteworthy, TsTX-I only induces relaxation on RPM suggesting that this protein selectively acts on inhibitory nerves.

Mechanisms of impaired vascular response to ANG II in perivascular injured carotid arteries of ovariectomized rat

The rabbit carotid artery, injured by silicone collar, presents a perivascular inflammatory response and alterations in vascular responsiveness. Considering that angiotensin II (Ang II) plays an important role in cardiovascular physiology and pathology and that cardiovascular disease increases in postmenopausal women, the aim of this study was to investigate whether the Ang II contractile response in ovariectomized rat carotid artery is modified after a vascular injury by silicone collar. The positioning of the silicone collar around the common carotid artery for 14 days leads to an increased cross-sectional area of adventitial layer with inflammatory cells and an extensive angiogenesis. The Ang II-induced contraction was significantly decreased in collared arteries when compared with contralateral arteries. The reduction in the constrictor effect of Ang II in collared arteries was not modified by the presence of indomethacin (a non-selective inhibitor of cyclooxygenase) or PD 123,319 (a selective antagonist of the Ang II AT2 receptor). Moreover, while endothelium removal induced an increase in the Ang II responsiveness of both arteries (collared and contralateral), the Emax induced by Ang II was still lower in collared arteries. However, the "in vitro" pretreatment of the arteries with an inhibitor of nitric oxide synthase enzyme (L-NAME) significantly enhanced the maximal contractions response to Ang II only in injured arteries. Furthermore, the expression of iNOS (inducible nitric oxide synthase) was observed in the adventitial layer of collared arteries, indicating that the NO formed in the adventitial layer has an important role in injured arteries. Moreover, our data show impairment of extracellular calcium mobilization, mediated by Ang II, in the collared artery, although the intracellular calcium mobilization was not modified by the injury. In conclusion, the increased production of NO and a decrease in the calcium influx displayed by Ang II in the collared artery appears to counteract and reduce the biologic effect of Ang II.

Effects of sibutramine on anxiety-related behaviours in rats

Sibutramine is an anorexiant drug that inhibits the reuptake of noradrenaline and serotonin, a pharmacological property shared with drugs clinically effective in treating anxiety pathologies. However, the effects of this compound on experimental and clinical anxiety have not been assessed yet. In this study, we evaluated the effects of sibutramine on anxiety-related behaviours which have been related to specific anxiety disorders. Acute injection of sibutramine (5, 10 or 20 mg kg(-1); intraperitoneally) in male Wistar rats impaired inhibitory avoidance in the elevated T-maze (ETM) and in the light/dark transition test, indicative of an anxiolytic effect. The drug also inhibited one-way escape in the ETM. Sibutramine, however, was ineffective in changing rat performance in the elevated plus-maze. Therefore, sibutramine decreased the expression of defensive behaviours that have been associated with generalized anxiety disorder (inhibitory avoidance) and with panic disorder (one-way escape). Yet, in contrast to what has been reported with drugs such as the tricyclic anti-depressants that also inhibit monoamine reuptake, the anxiolytic effects of sibutramine were revealed after a single administration.

Angiotensin II-Induced Relaxation of Anococcygeus Smooth Muscle via Desensitization of AT1Receptor, and Activation of AT2Receptor Associated with Nitric-Oxide Synthase Pathway

We evaluated the role of receptor desensitization, activation of AT(2) receptors, and enzymatic degradation of angiotensin II (Ang II) by amino/neutral endopeptidases in rat anococcygeus smooth muscle (ASM) relaxation. Ang II (0.3 nM to 10 microM) produced contractions (E(max) = 21.50 +/- 5.73%) followed by passive relaxations (E(max) reduced to 9.08 +/- 2.55%). Contractions were inhibited (E(max) = 13.67 +/- 2.03%) by losartan (0.1 microM; AT(1) antagonist) but not by PD123,319 [S-(+)-1-([4-(dimethylamino)-3-methylphenyl]methyl)-5-(diphenylacetyl)-4,5,6,7-tetrahydro-1H-imidazo(4,5-c)pyridine-6-carboxylic acid] (0.1 microM; AT(2) antagonist). Conversely, the passive relaxation was inhibited (E(max) = 18.00 +/- 3.45%) by PD123,319 but not by losartan. Ang II (0.3 microM to 100 microM) produced initial contractions (E(max) = 11.49 +/- 9.39%) followed by active relaxations [I(max) (maximum inhibition elicited by the agonist) = 47.85 +/- 4.23%] on strips precontracted by bethanechol (100 microM). A second administration of Ang II on the background of bethanechol (1 h later) resulted in stronger relaxations (I(max) = 64.03 +/- 5.47%) without the initial contractions. N(G)-Nitro-l-arginine methyl ester [nitric-oxide synthase (NOS) inhibitor], ODQ (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one; guanylate cyclase inhibitor), PD123,319, and tetrodotoxin (neurotoxin) inhibited the relaxations. The presence of AT(1) and AT(2) receptors was confirmed by Western blot. Experiments with amastatin (1 microM) and thiorphan (1 microM), aminopeptidase, and neutral endopeptidase inhibitors, respectively, excluded the involvement of enzymatic degradation in Ang II-induced relaxation of ASM. In conclusion, the rat ASM relaxation by Ang II is the result of active and passive relaxations. The passive relaxation depends on desensitization of excitatory AT(1) receptors, and the active relaxation is mediated by stimulation of AT(2) receptors and activation of the neuronal NOS/soluble guanylate cyclase pathway.

Structure–activity relationship of coordinated catecholamine in the [RuIII(NH3)4(catecholamine)]+ complex

The redox chemistry and pharmacological studies of the novel blue ruthenium(III)-catecholamine complexes were investigated in aqueous medium and compared to the free catecholamines. The [Ru(III)(NH3)4(catecholamine)]+ can be oxidized or reduced reversibly in one electron redox couples in aqueous solution. This is in contrast to the free catecholamines, which has a complicated electrochemical behavior due to coupled protonation process. The introduction of the ruthenium group reduces the intrinsic efficacy of the studied catecholamines. The [Ru(III)(NH3)4(catecholamine)]+ complex aqueous medium is more stable than the free catecholamines ligand in the same conditions.

Studies on the aroma of cupuassu liquor by headspace solid-phase microextraction and gas chromatography

Headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography with ion trap mass spectrometric detection and with atomic emission detection (GC-AED) was employed to identify possible odor-impact volatile organic compounds in cupuassu (Theobroma grandiflorum Spreng) liquor, as well as to quantify alkylpyrazines present in these samples. SPME fibers coated with 100 microm polydimethylsiloxane (PDMS), 65 microm PDMS-divinylbenzene (DVB) and 75 microm Carboxen (CAR)-PDMS were tested, the later being chosen for the optimized extraction procedure. The principal compounds found in the sample headspace were 3-methylbutanal, dimethylsulfide, dimethyldisulfide, beta-linalool and several alkylpyrazines (notably tetramethylpyrazine). The procedure for quantitation of the alkylpyrazines, using GC-AED for their separation and detection, allowed the detection of microg g(-1) levels of the analytes in the samples, with acceptable precision (R.S.D. less than 10%).

Inhibitory effects of atropine and hexamethonium on the angiotensin II-induced contractions of rat anococcygeus smooth muscles

We have evaluated the interaction between angiotensin II (Ang II) and the cholinergic transmission in anococcygeus smooth muscles isolated from rats treated (sympathectomised group) or not (vehicle group) with reserpine and alpha-methyl-p-tyrosine. For this, we contracted the tissues with Ang II in the presence and absence of atropine and hexamethonium. Ang II induced concentration-dependent contractions, which did not undergo temporal changes in tissues isolated from both groups of rats. In the vehicle group, Ang II induced more potent contractions than in the sympathectomised group. In the sympathectomised rat group, atropine inhibited the contractions induced by Ang II in a concentration-dependent fashion with no decrease in E(max). Additionally, hexamethonium inhibited the contraction induced by Ang II in a concentration-dependent fashion with a decrease in E(max). Association of atropine and hexamethonium produced Ang II-induced curves with rightward shifts from the control curve with a decrease in E(max). Incubation with N(G)-nitro-L-arginine methyl ester (L-NAME) reversed the effects of atropine and hexamethonium association. Conversely, in the vehicle group of rats, atropine and hexamethonium did not produce any significant effect. However, in the presence of yohimbine, atropine shifted the Ang II-induced curves to the right of the control curve with no E(max) decrease. Results suggest that there is a positive interaction between Ang II and cholinergic transmission in the rat anococcygeus smooth muscle mediated by angiotensin receptors located on pre-ganglionic cells.