Effects of Urophysial Extracts on the Cardiovascular System of the Carp, Cyprinus carpio

Urophysial extracts (UE) of carp induced (1) dose-dependent vasopressor effect on the carp, Cyprinus carpio, (2) dose-dependent contraction of the helically cut strip of carp ventral aorta, which contraction was not mediated by the adrenergic or cholinergic system, and (3) a positive inotropic effect on the arterial strip of the carp. These results suggest that increase in blood pressure elicited by UE is at least partially mediated through the effects of UE on the contraction of the ventral aorta, probably on the contraction of the arterioles, and on the enhancement of the contractile force of beating on the atrium. Dose dependent contraction of the aortic strip was elicited by partially purified urotensins I (UI) and II (UII) as well as UE of the carp. The contraction of the aortic strip by UE was almost entirely due to UII contained in the UE.