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1.
J Neural Transm (Vienna) ; 122(8): 1203-7, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25645866

RESUMO

Local perfusion of the sodium channel activator veratrine in mouse prelimbic medial prefrontal cortex (PL) induced c-Fos immunoreactivity in the sub-regions of amygdala. Co-perfusion of the NMDA receptor antagonist MK-801 diminished the c-Fos expression. Significant correlations were observed between c-Fos immunoreactivity and behavioral measures in the open-field test. The PL stimulation activates a neural network projecting to the amygdala via NMDA receptor-mediated glutamatergic neurotransmission. Anxiety-like behavior induced after the PL stimulation may be partly mediated through the activation of amygdala.


Assuntos
Tonsila do Cerebelo/metabolismo , Ansiedade/metabolismo , Córtex Pré-Frontal/metabolismo , Proteínas Proto-Oncogênicas c-fos/metabolismo , 6-Ciano-7-nitroquinoxalina-2,3-diona/farmacologia , Tonsila do Cerebelo/efeitos dos fármacos , Animais , Ansiedade/tratamento farmacológico , Maleato de Dizocilpina/farmacologia , Antagonistas de Aminoácidos Excitatórios/farmacologia , Imuno-Histoquímica , Masculino , Camundongos Endogâmicos C57BL , Atividade Motora/efeitos dos fármacos , Atividade Motora/fisiologia , Vias Neurais/efeitos dos fármacos , Vias Neurais/metabolismo , Fotomicrografia , Córtex Pré-Frontal/efeitos dos fármacos , Agonistas de Canais de Sódio/administração & dosagem , Veratrina/administração & dosagem
2.
Pharm Biol ; 52(1): 105-10, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24102122

RESUMO

CONTEXT: Hypericum caprifoliatum Cham & Schlecht (Guttiferae) extracts have a potential antidepressant-like effect in rodents. However, the molecular mechanisms by which these extracts exert this effect remain unclear. OBJECTIVE: This study evaluated the effect of HC1, a fraction obtained from H. caprifoliatum enriched in phloroglucinol derivatives, on the Na⁺, K⁺ ATPase activity in mouse brain and verified the influence of veratrine on the effect of HC1 in the forced swimming test (FST). MATERIALS AND METHODS: Veratrine (0.06 mg/kg) and HC1 (360 mg/kg) were given alone or combined i.p. 60 and p.o. 30 min, respectively, before FST. The effect of single and repeated administration (once a day for 3 consecutive days) of HC1 (360 mg/kg) on Na⁺, K⁺ ATPase activity was evaluated ex vivo in the cerebral cortex and hippocampus of mice subjected or not to FST. RESULTS: HC1 reduced the immobility time (103.15 ± 18.67 s), when compared to the control group (183.6 ± 9.51 s). This effect was prevented by veratrine (151.75 ± 22.19 s). Mice repeatedly treated with HC1 presented a significant increase in Na⁺, K⁺ ATPase activity, both in cerebral cortex (46 ± 2.41 nmol Pi/min·mg protein) and hippocampus (49.83 ± 2.31 nmol Pi/min·mg protein), in relation to the respective controls (30 ± 2.66 and 29.83 ± 2.31 nmol Pi/min·mg protein respectively). DISCUSSION AND CONCLUSION: The HC1 antidepressant-like effect on FST might be related to its capacity to inhibit Na⁺ influx. HC1 increases hippocampal and cortical Na⁺, K⁺ ATPase activities possibly through long-term regulatory mechanisms.


Assuntos
Antidepressivos/farmacologia , Depressão/tratamento farmacológico , Floroglucinol/farmacologia , Extratos Vegetais/farmacologia , Animais , Antidepressivos/administração & dosagem , Antidepressivos/isolamento & purificação , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Modelos Animais de Doenças , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Hypericum , Masculino , Camundongos , Floroglucinol/administração & dosagem , Floroglucinol/isolamento & purificação , Extratos Vegetais/administração & dosagem , Sódio/metabolismo , ATPase Trocadora de Sódio-Potássio/metabolismo , Natação , Veratrina/administração & dosagem , Veratrina/farmacologia
3.
Toxicon ; 40(10): 1471-81, 2002 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-12368117

RESUMO

The aim of this study was to investigate if the Na(+)-channel activating alkaloid veratrine is able to change the oxidative and m-ATPase activities of a fast-twitch glycolytic muscle (EDL, extensor digitorum longus) and slow-twitch oxidative muscle (SOL, soleus) in mice. Oxidative fibers and glycolytic fibers were more sensitive to veratrine than oxidative-glycolytic fibers 15, 30 and 60 min after the i.m. injection of veratrine (10 ng/kg) with both showing an increase in their metabolic activity in both muscles. In EDL, the m-ATPase reaction revealed a significant (p < 0.001) decrease (50%) in the number of type IIB fibers after 30 min while the number of type I fibers increased by 550%. Type I fibers decreased from 34% in control SOL to 17% (50% decrease) in veratrinized muscles, with a 10% decrease in type IIA fibers within 15 min. A third type of fiber appeared in SOL veratrinized muscle, which accounted for 28% of the fibers. Our work gives evidence that the changes in the percentage of the fiber types induced by veratrine may be the result, at least partially, from a direct effect of veratrine on muscle fibers and else from an interaction with the muscle type influencing distinctively the response of a same fiber type. Based on the results obtained in the present study the alterations in EDL may be related to the higher number of Na(+) channels present in this muscle whereas those in SOL may involve an action of veratrine on mitochondria. Although it is unlikely that the shift of enzymes activities induced by veratrine involves genotypic expression changes an alternative explanation for the findings cannot be substantiated by the present experimental approach.


Assuntos
Fibras Musculares de Contração Rápida/efeitos dos fármacos , Fibras Musculares de Contração Lenta/efeitos dos fármacos , Músculo Esquelético/efeitos dos fármacos , Veratrina/farmacologia , Adenosina Trifosfatases/análise , Adenosina Trifosfatases/metabolismo , Animais , Histocitoquímica , Injeções Intramusculares , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Fibras Musculares de Contração Rápida/enzimologia , Fibras Musculares de Contração Rápida/patologia , Fibras Musculares de Contração Lenta/enzimologia , Fibras Musculares de Contração Lenta/patologia , Músculo Esquelético/enzimologia , Músculo Esquelético/patologia , Miosinas/análise , Miosinas/metabolismo , Isoformas de Proteínas , Canais de Sódio/metabolismo , Veratrina/administração & dosagem
4.
Phytomedicine ; 9(4): 296-301, 2002 May.
Artigo em Inglês | MEDLINE | ID: mdl-12120810

RESUMO

In this study, we attempted to identify the interactions and mechanisms between veratrine and paeoniflorin on isolated mouse vas deferens. Paeoniflorin had no effect on isolated mouse vas deferens. Veratrine (1 x 10(-5) approximately 1 x 10(-3) g/ml) could directly induce contraction of isolated rat and mouse vas deferens. The concentration induced by veratrine (1 x 10(-5) g/ml) was completely inhibited by Ca2+-free solution and verapamil (1 x 10(-5) M), in both the epididymal and the prostatic portions of isolated mouse vas deferens. Naloxone (1 x 10(-5) M) did not alter the contraction induced by veratrine (1 x 10(-5) g/ml) in either the epididymal or the prostatic portions of isolated mouse vas deferens. Paeoniflorin (4.8 x 10(-5) g/ml) inhibited the contraction induced by veratrine (1 x 10(-5) g/ml) in both the epididymal and the prostatic portions of isolated mouse vas deferens. Paeoniflorin (4.8 x 10(-5) g/ml) potentiated norepinephrine (1 x 10(-5) M)-induced phasic contraction in the epididymal portion, but decreased contractions in the prostatic portion. Paeoniflorin (4.8 x 10(-5) g/ml) increased KCI (56 mM)-induced phasic contraction in the epididymal portion, but decreased the tonic contraction in either the epididymal or the prostatic portion. Veratrine (1 x 10(-5) g/ml)-induced contractions could be decreased by pretreatment with ryanodine (1 x 10(-5) M) in both the epididymal and the prostatic portions. Pretreatment with the combination of paeoniflorin (4.8 x 10(-5) g/ml) and ryanodine (1 x 10(-5) M) did not potentiate the inhibition of paeoniflorin in the veratrine-induced contraction in both the epididymal and the prostatic portions of isolated mouse vas deferens.


Assuntos
Benzoatos/farmacologia , Hidrocarbonetos Aromáticos com Pontes/farmacologia , Glucosídeos/farmacologia , Fitoterapia , Ducto Deferente/efeitos dos fármacos , Veratrina/farmacologia , Veratrum , Animais , Anti-Inflamatórios não Esteroides/administração & dosagem , Anti-Inflamatórios não Esteroides/farmacologia , Benzoatos/administração & dosagem , Hidrocarbonetos Aromáticos com Pontes/administração & dosagem , Bloqueadores dos Canais de Cálcio/administração & dosagem , Bloqueadores dos Canais de Cálcio/farmacologia , Relação Dose-Resposta a Droga , Interações Medicamentosas , Glucosídeos/administração & dosagem , Masculino , Camundongos , Camundongos Endogâmicos ICR , Monoterpenos , Contração Muscular/efeitos dos fármacos , Norepinefrina/farmacologia , Extratos Vegetais/farmacologia , Rianodina/farmacologia , Fatores de Tempo , Veratrina/administração & dosagem
5.
Circulation ; 103(12): 1674-80, 2001 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-11273996

RESUMO

BACKGROUND: Although the cardiovascular toxicity of cocaine is well recognized, considerable controversy remains as to the relative contribution of local norepinephrine reuptake inhibition versus central stimulatory effects of cocaine in eliciting its cardiovascular actions. The purpose of the present study was to determine the role of cardiac nerves in mediating the left ventricular (LV) and coronary hemodynamic responses to cocaine. METHODS AND RESULTS: We studied the cardiovascular response to acute cocaine administration (1 mg/kg) in 10 intact, conscious dogs and 6 dogs with ventricular denervation (VD). There were no significant differences in baseline hemodynamic parameters or plasma catecholamines between the 2 groups. In response to acute cocaine, LV and coronary hemodynamic responses were enhanced in the VD dogs. The enhanced systemic pressor and heart rate responses in VD dogs suggest that cardiac nerves mitigate the response to cocaine through ventricular mechanoreceptors rather than mediating the responses. CONCLUSIONS: These data suggest that peripheral blockade of norepinephrine reuptake is not the principal mechanism of the acute cardiac effects of cocaine. Rather, cardiac nerves modulate the effects of cocaine through baroreflex mechanisms. Thus, individual differences in baroreflex sensitivity may explain the hemodynamic variability observed in response to cocaine.


Assuntos
Cocaína/administração & dosagem , Coração/efeitos dos fármacos , Coração/inervação , Agonistas Adrenérgicos beta/administração & dosagem , Animais , Barorreflexo/efeitos dos fármacos , Pressão Sanguínea/efeitos dos fármacos , Cardiotônicos/administração & dosagem , Vasos Coronários/efeitos dos fármacos , Vasos Coronários/fisiologia , Cães , Relação Dose-Resposta a Droga , Feminino , Frequência Cardíaca/efeitos dos fármacos , Infusões Intravenosas , Masculino , Denervação Muscular , Contração Miocárdica/efeitos dos fármacos , Nitroglicerina/administração & dosagem , Norepinefrina/administração & dosagem , Fenilefrina/administração & dosagem , Vasodilatadores/administração & dosagem , Função Ventricular Esquerda/efeitos dos fármacos , Função Ventricular Esquerda/fisiologia , Veratrina/administração & dosagem , Vigília/fisiologia
6.
Histochem Cell Biol ; 116(6): 525-34, 2001 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11810194

RESUMO

The effects of veratrine have been investigated in mammalian, amphibian, and crustacean muscle, but not in fish. In this work, the action of veratrine was studied in the lateral muscle of the freshwater teleost Oreochromis niloticus after intramuscular injection. Histoenzymological typing and electron microscopy of muscle fibers before and 15, 30, and 60 min after veratrine injection (10 ng/kg fish) were used to indirectly assess the morphological changes and the oxidative and m-ATPase activities. In some cases, muscles were pretreated with tetrodotoxin to determine whether the ultrastructural changes were the result of Na(+) channel activation by veratrine. Veratrine altered the metabolism of fibers mainly after 30 min. Oxidative fibers showed decreased NADH-TR activity, whereas that of glycolytic and oxidative-glycolytic type fibers increased. There was no change in the m-ATPase activity of the three fiber types, except at 60 min postveratrine, when a novel fiber type, which showed no reversal after acidic and alkaline preincubations, appeared. Ultrastructural damage involved sarcomeres, myofibrils, and mitochondria, but the T-tubules remained intact. Pretreatment with tetrodotoxin (1 ng/ml) prevented the ultrastructural changes caused by veratrine. These results show that in fish skeletal muscle veratrine produces some effects that are not seen in mammalian muscle.


Assuntos
Ciclídeos , Músculo Esquelético/efeitos dos fármacos , Veratrina/toxicidade , Adenosina Trifosfatases/metabolismo , Antagonismo de Drogas , Injeções Intramusculares , Microscopia Eletrônica , Mitocôndrias Musculares/efeitos dos fármacos , Mitocôndrias Musculares/ultraestrutura , Fibras Musculares de Contração Rápida/efeitos dos fármacos , Fibras Musculares de Contração Rápida/enzimologia , Fibras Musculares de Contração Rápida/ultraestrutura , Fibras Musculares de Contração Lenta/efeitos dos fármacos , Fibras Musculares de Contração Lenta/enzimologia , Fibras Musculares de Contração Lenta/ultraestrutura , Músculo Esquelético/enzimologia , Músculo Esquelético/ultraestrutura , Sarcômeros/efeitos dos fármacos , Sarcômeros/ultraestrutura , Tetrodotoxina/toxicidade , Veratrina/administração & dosagem
7.
Nature ; 404(6778): 566, 2000 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-10766231
8.
Can J Physiol Pharmacol ; 77(10): 806-12, 1999 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-10588485

RESUMO

Experiments were undertaken to determine whether angiotensin (Ang) II concentration increases during massive sympathetic nervous system (SNS) activation and whether such an increase plays a role in the pathogenesis of SNS-induced left ventricular (LV) dysfunction. We also sought to determine whether excessive Ca2+ uptake through L-type channels due to intense adrenoceptor activation is responsible for the LV dysfunction. AngII concentration was measured in the plasma and myocardium before and after massively activating the SNS with an intracisternal injection of veratrine. In separate experiments, rabbits were given losartan, enalaprilat, enalaprilat plus HOE-140, nifedipine, -Bay K 4866, or saline before massively activating the SNS. LV function was evaluated 2.5 h later. The intense SNS activity caused plasma and myocardial AngII to increase by 400 and 437%, respectively. AngII receptor blockade did not prevent LV dysfunction. In contrast, enalaprilat reduced the degree of dysfunction, but its cardioprotection was abolished by HOE-140. Although nifedipine prevented SNS-induced LV dysfunction, administration of the Ca2+ channel opener, -Bay K 4866, did not increase its severity. Our results indicate that AngII is not involved in the pathogenesis of SNS-induced LV dysfunction and that the cardioprotection provided by angiotensin converting enzyme (ACE) inhibition is due to activation of a bradykinin pathway. Furthermore, the finding that the magnitude of the LV dysfunction was reduced by enalaprilat, and not increased by -Bay K 4866, suggests that intense adrenoceptor activation of L-type Ca2+ channels is not the primary pathogenetic mechanism.


Assuntos
Angiotensina II/fisiologia , Sistema Nervoso Simpático/fisiologia , Vasoconstritores/farmacologia , Disfunção Ventricular Esquerda/fisiopatologia , Antagonistas Adrenérgicos beta/farmacologia , Angiotensina II/sangue , Antagonistas de Receptores de Angiotensina , Inibidores da Enzima Conversora de Angiotensina/farmacologia , Animais , Antiarrítmicos/farmacologia , Anti-Hipertensivos/farmacologia , Pressão Sanguínea/efeitos dos fármacos , Cálcio/metabolismo , Agonistas dos Canais de Cálcio/farmacologia , Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio Tipo L/efeitos dos fármacos , Canais de Cálcio Tipo L/metabolismo , Canais de Cálcio Tipo L/fisiologia , Frequência Cardíaca/efeitos dos fármacos , Coelhos , Receptor Tipo 1 de Angiotensina , Receptor Tipo 2 de Angiotensina , Sistema Nervoso Simpático/efeitos dos fármacos , Veratrina/administração & dosagem , Veratrina/farmacologia
9.
J Appl Physiol (1985) ; 84(2): 618-23, 1998 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-9475874

RESUMO

We evaluated the effect of neuropeptide Y (NPY) on the hemodynamics of the isolated rabbit lung perfused at constant flow and outflow pressure. Doses of 10(-8) and 10(-7) M NPY increased pulmonary arterial pressure (Ppa) from 11.5 +/- 1.0 (SE) mmHg to, respectively, 16.4 +/- 1.5 and 26.0 +/- 3.8 mmHg (P < 0.05, n = 5 mmHg lungs), with 78 +/- 4% of the increase at 10(-7) M resulting from an increased arterial resistance. At the latter dose, pulmonary capillary pressure increased from 5.8 +/- 0.9 to 9.4 +/- 1.0 mmHg (P < 0.05). When administered in the presence of norepinephrine, 10(-8) and 10(-7) M NPY (n = 6) produced extreme increases in Ppa to 66.1 +/- 20.5 and 114.7 +/- 25.5 mmHg, respectively, that were due primarily to an increased arterial resistance. To determine the significance of circulating NPY as a pulmonary vasoactive agent, we measured plasma NPY-like immunoreactivity in anesthetized rabbits after massively activating the sympathetic nervous system with veratrine. NPY-like immunoreactivity increased from 74 +/- 10 to 111 +/- 10 (SE) pM (P < 0.05). Thus, although NPY is a potent vasoconstrictor in the rabbit lung, it is not likely that plasma NPY concentrations rise sufficiently, even after massive sympathetic nervous system activation, to produce pulmonary vasoconstriction in the intact rabbit.


Assuntos
Hemodinâmica/fisiologia , Neuropeptídeo Y/fisiologia , Circulação Pulmonar/fisiologia , Animais , Cisterna Magna , Técnicas In Vitro , Injeções , Neuropeptídeo Y/sangue , Neuropeptídeo Y/farmacologia , Norepinefrina/farmacologia , Perfusão , Circulação Pulmonar/efeitos dos fármacos , Coelhos , Sistema Nervoso Simpático/efeitos dos fármacos , Sistema Nervoso Simpático/fisiologia , Resistência Vascular/efeitos dos fármacos , Resistência Vascular/fisiologia , Vasoconstrição/efeitos dos fármacos , Vasoconstrição/fisiologia , Vasoconstritores/farmacologia , Veratrina/administração & dosagem , Veratrina/farmacologia
10.
J Gen Physiol ; 99(5): 699-720, 1992 May.
Artigo em Inglês | MEDLINE | ID: mdl-1318939

RESUMO

Veratridine modification of Na current was examined in single dissociated ventricular myocytes from late-fetal rats by applying pulses to -30 mV for 50 ms every 2 or 5 s from a holding potential of -100 mV (20 degrees C) and measuring amplitude, Itail, and time constant, tau tail, of the post-repolarization inward tail current induced by the alkaloid. Increasing the pH of a 30 microM veratridine superfusate from 7.3 to 8.3 (which increases the fraction of uncharged veratridine molecules from 0.5 to 5% while decreasing that of protonated molecules from 99.5 to 95%) increased Itail by a factor of 2.5 +/- 0.5 (mean +/- SEM; n = 3). Switching from 100 microM veratridine superfusate at pH 7.3 to 10 microM at pH 8.3 did not affect the size of Itail (n = 4). Intracellular (pipette) application of 100 microM veratridine at pH 7.3 or 8.3 produced small Itail's suggesting transmembrane loss of alkaloid. If this was compensated for by simultaneous extracellular application of 100 microM veratridine at a pH identical to intracellular pH, Itail (measured relative to the maximum amplitude induced by a combination of 100 microM veratridine and 1 microM BDF 9145 in the same cell) at pHi 7.3 did not significantly differ from that at pHi 8.3 (84 +/- 4 vs. 70 +/- 6%; n = 3 each). Results from six control cells and five cells subjected to extra- and/or intracellularly increased viscosity by the addition of 0.5 or 1 molal sucrose showed that increasing intracellular viscosity 1.6- and 2.5-fold increased tau tail 1.5- and 2.3-fold, respectively, while a selective 2.5-fold increase of extracellular viscosity did not significantly affect tau tail.(ABSTRACT TRUNCATED AT 250 WORDS)


Assuntos
Miocárdio/metabolismo , Canais de Sódio/efeitos dos fármacos , Veratridina/farmacologia , Veratrina/farmacologia , Animais , Sítios de Ligação , Interações Medicamentosas , Eletroquímica , Coração Fetal/efeitos dos fármacos , Coração Fetal/metabolismo , Concentração de Íons de Hidrogênio , Técnicas In Vitro , Ratos , Ratos Endogâmicos , Canais de Sódio/metabolismo , Veratridina/administração & dosagem , Veratrina/administração & dosagem , Viscosidade
11.
J Physiol ; 451: 91-107, 1992.
Artigo em Inglês | MEDLINE | ID: mdl-1403833

RESUMO

1. The effect of activation of left ventricular cardiac receptors on carotid baroreflex control of blood pressure, heart rate, cardiac output, and total peripheral resistance was determined in conscious dogs. Previous studies in conscious subjects assessed only the effect on baroreflex control of heart rate. 2. Dogs with denervated aortic baroreceptors were equipped with aortic flow probes, cardiac pacing electrodes, and catheters in the aorta, vena cava, and left circumflex coronary artery. Both carotid sinus regions were prepared for reversible vascular isolation. 3. Left ventricular receptors were stimulated by an infusion of veratrine (0.1-1.0 micrograms kg-1 min-1) into the left circumflex coronary artery. 4. Veratrine infusion decreased control blood pressure only 10 +/- 2 mmHg, but it decreased the range of baroreflex control of blood pressure by 50% and decreased maximum baroreflex gain by 42%. Both the cardiac output and total peripheral resistance components of the baroreflex were attenuated. 5. Baroreflex control of blood pressure was unaffected by intravenous veratrine or by intracoronary infusion of vehicle. 6. Intracoronary veratrine had no effect after autonomic ganglionic blockade. 7. When cardiac output was kept nearly constant (by beta-adrenergic and cholinergic receptor blockade or by beta-blockade and cardiac pacing), intracoronary veratrine still attenuated baroreflex control of blood pressure and total peripheral resistance. Veratrine impaired the ability of the baroreflex to utilize alpha-adrenergic mechanisms to control total peripheral resistance. 8. We conclude that activation of ventricular receptors attenuates baroreflex regulation of blood pressure in conscious dogs through an attenuation of baroreflex control of both cardiac output and total peripheral resistance.


Assuntos
Pressão Sanguínea/efeitos dos fármacos , Pressorreceptores/efeitos dos fármacos , Veratrina/administração & dosagem , Animais , Pressão Sanguínea/fisiologia , Seio Carotídeo/efeitos dos fármacos , Seio Carotídeo/fisiologia , Vasos Coronários , Cães , Feminino , Ventrículos do Coração/efeitos dos fármacos , Ventrículos do Coração/inervação , Hemodinâmica/efeitos dos fármacos , Hemodinâmica/fisiologia , Infusões Intra-Arteriais , Masculino , Pressorreceptores/fisiologia , Reflexo/efeitos dos fármacos , Reflexo/fisiologia , Resistência Vascular/efeitos dos fármacos , Resistência Vascular/fisiologia , Função Ventricular
12.
Nihon Jinzo Gakkai Shi ; 33(11): 1055-61, 1991 Nov.
Artigo em Japonês | MEDLINE | ID: mdl-1808357

RESUMO

Renal nerve and cardiovascular effects of intrarenal veratrine (Ver) were investigated using the cross-perfused kidney preparations of anesthetized dogs. Ver (1 and 3 micrograms/kg), injected as a bolus, elicited increases in arterial blood pressure (ABP), heart rate (HR) and renal efferent nerve activity (RENA). Ganglion blockade, hexametonium (2 mg/kg) markedly diminished increases in ABP, HR and RENA induced by Ver. In a separate group of animals, significant increases in renal afferent nerve activity (RANA) occurred after Ver administration. It is concluded that selective intrarenal Ver activates renal nerve afferents, and these results in cardiovascular changes are consistent with efferent sympathetic activation.


Assuntos
Pressão Sanguínea/efeitos dos fármacos , Frequência Cardíaca/efeitos dos fármacos , Rim/inervação , Células Receptoras Sensoriais/efeitos dos fármacos , Sistema Nervoso Simpático/efeitos dos fármacos , Veratrina/farmacologia , Animais , Cães , Compostos de Hexametônio/farmacologia , Injeções Intra-Arteriais , Artéria Renal/fisiologia , Veratrina/administração & dosagem , Veratrina/antagonistas & inibidores
13.
Respir Med ; 85 Suppl A: 51-5, 1991 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-2034836

RESUMO

With cats anaesthetized with sodium pentobarbital we studied how veratrine-induced reflexes interact with cough. Cough was elicited by mechanical stimulation of tracheobronchial mucosa and its intensity was evaluated from the changes in oesophageal pressure. Veratrine injected intravenously produced apnoea, bradycardia and long-lasting hypotension. With each dose the intensity of cough was significantly decreased during the apnoea. When the mechanical stimulus was repeated during the breathing following apnoea with remaining hypotension, cough intensity parameters were not changed from control. Veratrine injected intracardially caused bradycardia, hypotension, and decreases in respiratory rate and tidal volume. The intensity of cough elicited just after injection of veratrine was also significantly decreased. We suggest that veratrine-induced reflexes depress the cough reflex mainly by inhibitory reflexes arising from cardiac receptors. The inhibition of cough is probably mediated indirectly via the inhibition of medullary respiratory neurons.


Assuntos
Tosse/fisiopatologia , Reflexo/efeitos dos fármacos , Veratrina/farmacologia , Animais , Apneia/induzido quimicamente , Bradicardia/induzido quimicamente , Gatos , Relação Dose-Resposta a Droga , Feminino , Coração/efeitos dos fármacos , Hipotensão/induzido quimicamente , Injeções Intravenosas , Masculino , Veratrina/administração & dosagem
14.
Am J Physiol ; 259(1 Pt 2): F18-25, 1990 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-2375391

RESUMO

The present study was undertaken to determine whether intracoronary (left circumflex) veratrine (ICV) infusions and increases in left ventricular (LV) systolic pressure influence renal circulatory and excretory function in chronically instrumented conscious dogs (n = 19). Thirty minutes of ICV infusions decreased arterial pressure by 15-20 mmHg, but heart rate, urine flow, sodium excretion, and free water clearance did not change. Intravenous nitroprusside infusions, which also lowered arterial pressure by 15-20 mmHg, increased heart rate while urine flow, sodium excretion, and free water clearance were significantly decreased. Heart rate and renal excretory function also did not change during a 15- to 20-mmHg decrease in arterial pressure when LV systolic pressure was simultaneously raised to approximately 170 mmHg by ascending aortic occlusion. The topical application of a local anesthetic in the region of the left main coronary artery abolished the Bezold-Jarisch reflex and the attenuation of hypotension-induced salt and water retention and tachycardia by ICV. Renal plasma flow and glomerular filtration rate were not altered during any of the above experimental treatments. These results suggest that in the conscious dog chemical and mechanical stimulation of LV sensory receptors with afferents in the pericoronary region can modulate the neurohumoral reflex control of renal excretory function independent of local filtration effects.


Assuntos
Estenose da Valva Aórtica/fisiopatologia , Hipotensão/fisiopatologia , Rim/fisiopatologia , Veratrina/farmacologia , Animais , Pressão Sanguínea/fisiologia , Cateterismo Cardíaco , Estado de Consciência/fisiologia , Cães , Frequência Cardíaca/efeitos dos fármacos , Frequência Cardíaca/fisiologia , Masculino , Nitroprussiato/farmacologia , Circulação Renal/efeitos dos fármacos , Circulação Renal/fisiologia , Fatores de Tempo , Micção/efeitos dos fármacos , Micção/fisiologia , Veratrina/administração & dosagem
15.
Proc Soc Exp Biol Med ; 193(3): 225-31, 1990 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-2304925

RESUMO

The objective of this study was to determine whether myocardial contractility is depressed by intense activation of the sympathetic nervous system. A massive sympathetic discharge was produced by injecting veratrine or sodium citrate into the cisterna magna of anesthetized rabbits (n = 10). Two and one-half hr later, the hearts were isolated and their left ventricular (LV) performance evaluated and compared with the LV performance of hearts isolated from control animals (n = 10). LV performance was evaluated from steady-state peak isovolumic systolic and end-diastolic pressures that were generated at various end-diastolic volumes (LV function curves). The relationship between peak LV systolic pressure (or the average peak developed LV wall stress) and LV end-diastolic volume was rotated downward (P less than 0.01) in the hearts removed from rabbits treated with veratrine or citrate. The LV end-diastolic pressure or LV end-diastolic wall stress of these hearts was not different from control at any end-diastolic volume. The diminished ability of the experimental hearts to develop systolic pressure or wall stress suggests that intense sympathetic activation depressed contractility. Severely damaged myofibers, located largely in the subendocardium, were found in these hearts. Furthermore, the depressed contractility was not related to pulmonary edema since only 2 of 10 rabbits developed edema.


Assuntos
Contração Miocárdica/fisiologia , Sistema Nervoso Simpático/fisiologia , Animais , Cisterna Magna , Citratos/administração & dosagem , Citratos/farmacologia , Ácido Cítrico , Epinefrina/sangue , Água Extravascular Pulmonar/efeitos dos fármacos , Feminino , Ventrículos do Coração/efeitos dos fármacos , Ventrículos do Coração/ultraestrutura , Hemodinâmica/efeitos dos fármacos , Masculino , Norepinefrina/sangue , Coelhos , Sistema Nervoso Simpático/efeitos dos fármacos , Função Ventricular , Veratrina/administração & dosagem , Veratrina/farmacologia
16.
J Auton Nerv Syst ; 15(3): 205-16, 1986 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-3958438

RESUMO

The distribution and location of slowly adapting pulmonary stretch receptors (PSRs) that affect respiratory and cardiovascular functions were investigated in anaesthetized, artificially ventilated and thoracotomized cats. The location of the receptors was done by punctate stimulation and local mechanical stimulation after occlusion of the trachea at end-expiration (Exp). 84% of the slowly adapting PSRs were found to be located in the lung parenchyma. The occlusion technique alone was found to be of help only for a limited population of stretch receptors. The intrapulmonary distribution of PSRs revealed a greater percentage of receptors in the diaphragmatic lobe. No correlation was found between conduction velocity and receptor location. Both the slowly and rapidly conducting receptors were found to be scattered throughout the entire lung parenchyma. However, it was observed that while the majority of low threshold (LT) PSRs were located closer to the hilum of the lung, many of the higher threshold (HT) receptors were located farther away. In addition, when veratrine was administered into the pulmonary circulation, 83% of HT PSRs studied were stimulated by the drug, while only 25% of LT PSRs under study could be stimulated this way. The significance of the above findings is discussed.


Assuntos
Adaptação Fisiológica , Pulmão/inervação , Mecanorreceptores/anatomia & histologia , Receptores Pulmonares de Alongamento/anatomia & histologia , Obstrução das Vias Respiratórias/fisiopatologia , Animais , Gatos , Eletrofisiologia , Feminino , Injeções Intravenosas , Masculino , Condução Nervosa/efeitos dos fármacos , Estimulação Física , Veratrina/administração & dosagem
17.
Acta Physiol Acad Sci Hung ; 47(2-3): 117-25, 1976.
Artigo em Inglês | MEDLINE | ID: mdl-1031246

RESUMO

The concentration dependence of the effect of veratrine in inducing depolarization and membrane potential oscillation in the frog sartorius muscle has been studied. (1) On increasing the veratrine concentration from 0.025 to 1 mM, the latency period of the development of membrane potential oscillation and depolarization is proportionally shortened. (2) On changing the veratrine concentration from 0.025 to 1 mM, the magnitude of depolarization is raised logarithmically. (3) When the veratrine concentration reaches 0.05-0.1 mM, both the amplitude and the frequency of the membrane potential oscillation increase. On rising to 1 mM, a further increase in frequency to eight-fold occurs especially in the later phase of oscillation. At this concentration range, the amplitude of oscillation inversely proportional to the concentration of veratrine. (4) On increasing the veratrine concentration above 0.1 mM, the membrane potential oscillation ceases after a temporary rise of frequency. This inhibitory effect of veratrine is, however, reversible, and oscillations appear again, despite the absence of veratrine in Ringer's solution. This also proves the persistance of the veratrine effect.


Assuntos
Potenciais da Membrana/efeitos dos fármacos , Músculos/efeitos dos fármacos , Veratrina/farmacologia , Animais , Anuros , Relação Dose-Resposta a Droga , Técnicas In Vitro , Músculos/fisiologia , Veratrina/administração & dosagem
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