Pharmacological Effects of Urotensins

Abstract

The blood pressure lowering effect of urotensin I, a vasodilatatory peptide obtained from urophyses of a bony fish species (Catostomus commersoni) was studied by tail plethysmography in conscious normotensive and in spontaneously hypertensive rats. Urotensin I (10 mU/100 g body weight i.v.) lowered the blood pressure, depending on the preinjection level. The lowering of pressure amounted to 12.4 ± 1.28 % of the preinjection level in normotensive rats, 17.9 ± 1.46 % in hypertensive females and to 28.9 ± 1.06 % in hypertensive males. The differences between the normotensive and each group of hypertensive animals were statistically significant (p < 0.05 to p < 0.001).The blood pressure-lowering effect of urotensin I was less pronounced in female hypertensive rats than in hypertensive males of the same age.No significant difference was found in the preinjection blood pressure level between the group of younger (169–176 days) and older (247–249 days) male hypertensive rats. However, the blood pressure in the younger rats was significantly more affected by urotensin I than that in the older rats (p < 0.05).

Isolation, analysis of structure, synthesis, and biological actions of urotensin I neuropeptides

“…rat (1 I), (ii) relaxation of helically cut strips of rat mesenteric artery previously contracted with noradrenaline (23), or (iii) measuring hypotension in the conscious rat by the tail-cuff method (13).…”

“…The physiological function(s) of the caudal neurosecretory system and of its putative hormonal substances, the urotensins (8), in fishes, have not been defined. Early pharmacologicd observations in our laboratory indicated an unusually prolonged duration of the vasodilatory hypotensive action of this peptide in mammals; after intravenous administration, the resultant hypotension lasted for several hours, in a dose-dependent manner, in all mammalian species tested (1 1, 12) and in excess of 24 h after subcutaneous administration in the conscious rat (13). Subsequently, a strikingly selective site and mode of action was observed in the anaesthetized dog (or monkey).…”