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Titolo:
CHARACTERIZATION OF PREJUNCTIONAL 5-HT RECEPTORS MEDIATING INHIBITIONOF SYMPATHETIC VASOPRESSOR RESPONSES IN THE PITHED RAT
Autore:
VILLALON CM; CONTRERAS J; RAMIREZSANJUAN E; CASTILLO C; PERUSQUIA M; TERRON JA;
Indirizzi:
IPN,CINVESTAV,DEPT FARMACOL & TOXICOL,SECC TERAPEUT EXPTL,APDO POSTAL22026 MEXICO CITY 14000 DF MEXICO IPN,ENCB,DEPT FISIOL MEXICO CITY 11340 DF MEXICO IPN,ESM,DEPT FISIOL & FARMACOL MEXICO CITY 11340 DF MEXICO UNAM,INST INVEST BIOMED MEXICO CITY DF MEXICO
Titolo Testata:
British Journal of Pharmacology
fascicolo: 8, volume: 116, anno: 1995,
pagine: 3330 - 3336
SICI:
0007-1188(1995)116:8<3330:COP5RM>2.0.ZU;2-1
Fonte:
ISI
Lingua:
ENG
Soggetto:
NORADRENALINE RELEASE; 5-HT1-LIKE RECEPTOR; SEROTONIN RECEPTOR; SAPHENOUS-VEIN; PIG; 5-HYDROXYTRYPTAMINE; TACHYCARDIA; ARTERY; DOG;
Keywords:
5-HYDROXYTRYPTAMINE; 5-HT1-LIKE RECEPTORS; PREJUNCTIONAL INHIBITION; SYMPATHETIC OUTFLOW;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
34
Recensione:
Indirizzi per estratti:
Citazione:
C.M. Villalon et al., "CHARACTERIZATION OF PREJUNCTIONAL 5-HT RECEPTORS MEDIATING INHIBITIONOF SYMPATHETIC VASOPRESSOR RESPONSES IN THE PITHED RAT", British Journal of Pharmacology, 116(8), 1995, pp. 3330-3336

Abstract

1 It has recently been shown that continuous infusions of 5-hydroxytryptamine (5-HT) are able to inhibit, in a dose-dependent manner, the presser responses induced by preganglionic (T-7-T-9) sympathetic stimulation in pithed rats pretreated with desipramine (50 mu g kg(-1), i.v.). This inhibitory effect, besides being significantly more pronouncedat lower frequencies of stimulation (0.03-1 Hz) and devoid of tachyphylaxis, is reversible after interrupting the infusions of 5-HT (up to 5.6 mu g kg(-1) min(-1)). In the present study we have characterized the pharmacological profile of the receptors mediating the above inhibitory effect of 5-HT. 2 The inhibition induced by 5.6 mu g kg(-1) min(-1) of 5-HT on sympathetically-induced presser responses was not blocked after i.v. treatment with physiological saline (I ml kg(-1)), ritanserin (0.1 mg kg(-1)), MDL 72222 (0.15 mg kg(-1)) or tropisetron (3 mg kg(-1)), which did not modify the sympathetically-induced presser responses per se, but was significantly antagonized by the 5-HT1-like and 5-HT2 receptor antagonist, methysergide (0.3 mg kg(-1)), which also produced a slight attenuation of the presser responses to 0.03 and 0.1 Hz per se. 3 Unexpectedly and contrasting with methysergide, the 5-HT1-like and 5-HT2 receptor antagonists, methiothepin (0.01, 0.03 and 0.1 mg kg(-1)) and metergoline (1 and 3 mg kg(-1)), apparently failed to block the above 5-HT-induced inhibition. Nevertheless, it is noteworthythat these antagonists also blocked the electrically-induced presser responses per se, presumably by blockade of vascular alpha(1)-adrenoceptors and, indeed, this property might have masked their potential antagonism at the inhibitory 5-HT1-like receptors. 4 Consistent with the above findings, 5-carboxamidotryptamine (5-CT, a potent 5-HT1-like receptor agonist), metergoline and methysergide mimicked the inhibitory action of 5-HT with the following rank order of agonist potency: 5CT much greater than 5-HT>metergoline greater than or equal to methysergide. 5 Taken together, the above results suggest that the inhibitory action of 5-HT on the electrically-induced presser responses is primarily mediated by an action on inhibitory prejunctional 5-HT1-like receptorsleading to a decrease in the sympathetic nerve discharge. Interestingly, 5-HT-induced excitatory mechanisms could be made manifest once theinhibitory action of 5-HT had been antagonized.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 28/09/20 alle ore 18:42:58