Depressor and regionally-selective vasodilator effects of human and rat urotensin II in conscious rats

The regional haemodynamic effects of rat or human urotensin II (U-II) 3, 30 , 300 and 3000 pmol kg(-1), i.v.) were assessed in separate groups of consc ious, unrestrained, male, Sprague-Dawley rats (n=8 in each). Rat and human U-II had similar effects. At a dose of 3 pmol kg(-1), neither peptide had a ny significant action, while at a dose of 30 pmol kg(-1), there was a trans ient mesenteric vasodilatation (significant only for rat U-II). At doses of 300 and 3000 pmol kg(-1), there were dose-dependent tachycardias, and mese nteric and hindquarters hyperaemic vasodilatations. Thus, in conscious rats , the predominant cardiovascular action of rat and human U-II is vasodilata tion. This is in contrast to recent findings with human U-II in non-human p rimates, but is consistent with effects on human isolated resistance vessel s.