AJP - Heart and Circulatory Physiology, Vol 258, Issue 5 1550-H1558, Copyright © 1990 by American Physiological Society
Comparative responses to endothelin 2 and sarafotoxin 6b in systemic vascular bed of cats
R. K. Minkes and P. J. Kadowitz
Department of Pharmacology, Tulane University School of Medicine, New Orleans, Louisiana 70112.
Cardiovascular responses to endothelin 2 (ET-2) and sarafotoxin 6b (S6b)
were investigated in the cat. ET-2 (0.1-1 nmol/kg iv) decreased or elicited
biphasic changes in arterial pressure (AP), whereas S6b (0.1-1 nmol/kg iv)
only decreased AP. Central venous pressure (CVP), cardiac output (CO), and
pulmonary arterial pressure (PAP) were increased. ET-2 produced biphasic
changes in systemic vascular resistance (SVR), whereas S6b decreased SVR at
the two lower doses and caused a biphasic change at the 1 nmol/kg dose. The
effects of ET-1 and ET-2 were similar, whereas the effects of S6b were
similar to ET-3. ET-2 and S6b had small effects on right ventricular
contractile force and caused transient increases in heart rate. Distal
aortic blood flow was increased in response to all doses of both peptides,
whereas increases in carotid blood flow were observed only in response to
the higher doses of ET-2 and S6b. ET-2 produced dose-dependent decreases in
superior mesenteric artery (SMA) blood flow, whereas decreases in SMA flow
in response to S6b were observed only at the 1 nmol/kg dose. Renal blood
flow was decreased significantly only at the higher doses of ET-2 and S6b.
The present data show that ET-2 and S6b can produce both vasodilation and
vasoconstriction in the systemic and regional vascular beds of the cat and
demonstrate previously unrecognized vasodilator activity in response to
S6b. It is concluded that ET-2 and S6b produce complex cardiovascular
responses in the anesthetized cat.
