Vasopressin mediates the pressor effects of endothelin in the subfornical organ of the rat.
J Pharmacol Exp Ther
; 277(2): 1034-42, 1996 May.
Article
en En
| MEDLINE
| ID: mdl-8627514
ABSTRACT
The potent vasoconstrictor peptide endothelin may affect central cardiovascular function in areas with incomplete blood-brain barrier such as the subfornical organ (SFO). In these studies, we determine whether microinjection of endothelin-1 (ET-1) into the SFO increases blood pressure (BP) in a dose-related manner and investigate the potential involvement of sympathetic and vasopressinergic mechanisms. In urethane-anesthetized Sprague-Dawley rats, BP was recorded intra-arterially, and ET-1 (0.125-6.0 pmol/60 nl) was microinjected stereotaxically into the SFO. Whereas vehicle (60 nl) did not change mean BP or HR, ET-1 evoked a dose-related pressor and bradycardic effect. The maximal changes were noted at the 1-pmol dose. No significant hemodynamic effects were observed with ET-1 microinjection in areas immediately surrounding the SFO or into the SFO of rats pretreated with a specific endothelin antagonist. In animals instrumented for recording of renal sympathetic nerve activity (RSNA), the administration of ET-1 (1 pmol/60 nl) evoked pressor (14 +/- 5 mm Hg) and bradycardic (-41 +/- 12 bpm) effects with a decrease in RSNA (16% +/- 3%). The effects on HR and RSNA seem to be mediated by baroreflex changes because in sino-aortic denervated rats, ET-1 pressor effects occur without inhibition of HR or RSNA. We documented the involvement of vasopressin in ET-1 actions by using vasopressin antagonists that inhibited the effects evoked by ET-1 administration. In addition, increases in vasopressin plasma levels were demonstrated at the time of the maximal effect of this peptide. These results indicate that ET-1 acting in the SFO increases BP by a vasopressinergic mechanism.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Órgano Subfornical
/
Presión Sanguínea
/
Vasopresinas
/
Endotelinas
Límite:
Animals
Idioma:
En
Revista:
J Pharmacol Exp Ther
Año:
1996
Tipo del documento:
Article
País de afiliación:
Estados Unidos
Pais de publicación:
EEUU
/
ESTADOS UNIDOS
/
ESTADOS UNIDOS DA AMERICA
/
EUA
/
UNITED STATES
/
UNITED STATES OF AMERICA
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US
/
USA