Effects of rat urotensin II on coronary flow and myocardial eNOS protein expression in isolated rat heart.
OBJECTIVE
To examine the effects of urotensin II, a recently discovered endogenous peptide, on coronary flow (CF), cardiac function, and endothelial nitric oxide synthase (eNOS) expression in isolated rat hearts.


METHODS
Heart was isolated and perfused retrogradely via the aorta in Langendorff mode. Rat urotensin II was administered in the perfusion solution. The eNOS content in myocardium was determined by Western blot.


RESULTS
Rat urotensin II had no effect on the heart rate, left ventricular systolic pressure, left ventricular end-diastolic pressure, or +/-dp/dt(max). While rat urotensin II dose-dependently increased CF. CF was increased by 11.43 %, 6.67 %, 6.62 %, 6.56 %, 6.36 %, and 5.86 % respectively in a time-dependent manner at 5, 10, 15, 20, 25, and 30 min after injection of rat urotensin II 6.66 x 10(-2) microg. The maximal effect on CF was found at 5 min following urotensin II administration. N(G)-nitro-L-arginine methyl ester (L-NAME) did not prevent the increased CF in response to urotensin II. Rat urotensin II dose-dependently increased the cardiac eNOS protein expression and this effect was not inhibited by L-NAME.


CONCLUSIONS
Rat urotensin II did not alter cardiac function but increased CF and the amount of myocardial eNOS protein in the isolated rat heart. The increased CF was independent of the involvement of eNOS.
Li
Ling
L
Department of Pharmacology, Second Military Medical University, Shanghai, China.
Yuan
Wen-jun
WJ
Su
Ding-feng
DF
D000818:Animals; D003326:Coronary Circulation / Q000187:drug effects*; D006334:Heart Function Tests; D066298:In Vitro Techniques; D008297:Male; D009206:Myocardium / Q000201:enzymology*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III; D051381:Rats; D017207:Rats, Sprague-Dawley; D014579:Urotensins / Q000494:pharmacology*
D014579:Urotensins; C029677:urotensin II; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D019331:NG-Nitroarginine Methyl Ester