Effects of a vasorelaxing factor liberated by the rat isolated atria on rat aortic rings with and without endothelium.
In 1993, Illanes et al. described a vasoactive factor, the auricular vasorelaxing factor (AVF), by controlled distension of rat isolated atria. This factor produces vasodilation, antagonizing the vasoconstrictor action of phenylephrine. We now report assays by using isolated rat aortic rings and norepinephrine as a vasoconstrictor. Isolated thoraxic aortic rings were mechanically deprived of endothelium and subjected to the effects of increasing, cumulative concentrations of 6.6 x 10(-11) M to 6.6 x 10(-7) M norepinephrine. AVF significantly decreases the constrictor effect of norepinephrine assayed afterward, shifting the vasoconstrictor dose-response relation to the right. The effect was the same in rat aortic rings with or without endothelium. Subjecting aortic rings to control vehicle samples did not alter the dose-response curve to norepinephrine. We conclude that AVF antagonizes the norepinephrine vasoconstrictor effect in rat isolated aortic rings and that the mechanism of this vasorelaxing effect is independent of any contribution from the endothelial cells.
Illanes
A G
AG
Department of Physiological Sciences, School of Medicine, Orient University-Venezuela, Ciudad Bolivar.
Correa
R C
RC
Martínez
P J
PJ
D000818:Animals; D001011:Aorta / Q000187:drug effects* / Q000502:physiology; D016275:Atrial Function; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology; D008297:Male; D009638:Norepinephrine / Q000378:metabolism / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D014662:Vasoconstrictor Agents / Q000378:metabolism / Q000494:pharmacology*; D014664:Vasodilation / Q000187:drug effects
D014662:Vasoconstrictor Agents; D009638:Norepinephrine