Cardiovascular effects of endothelin-11–31 microinjected into the nucleus tractus solitarius of anesthetized rats

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Abstract

Endothelin-11–31 (ET-11–31) is a 31-amino-acid vasoactive peptide that plays an important role in the regulation of cardiovascular function. However, the cardiovascular effects of central ET-11–31 are still not fully understood. In this study, we assess the effects of ET-11–31 within the nucleus tractus solitarius (NTS) of anesthetized rats and explore the underlying mechanisms of these effects. Bilateral microinjections of ET-11–31 into the NTS produced dose-dependent hypotension and bradycardia, very similar to the effects of a unilateral microinjection of ET-11–31 into the NTS. Bilateral microinjections of ET-11–31 into the NTS significantly decreased baroreflex function in a time-dependent manner. The hypotensive and bradycardic effects induced by the microinjection of ET-11–31 into the NTS were significantly decreased by the ETA receptor antagonist BQ123 and by kynurenic acid, but not by the ETB receptor antagonist BQ788. These results show that ET-11–31 injected into the NTS produces hypotension and bradycardia, mediated by ETA receptors and, at least partly, by the glutamate receptor.

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