Amunine (ovine CRF), urotensin I and sauvagine, three structurally-related peptides, produce selective dilation of the mesenteric circulation.

Three synthetic peptides, urotensin I, sauvagine and ovine CRF, have less than 50% sequence homology. In the dog, all three produce selective mesenteric dilation, which appears to be solely responsible for a decrease in peripheral resistance and systemic arterial blood pressure. Urotensin I and sauvagine were found to be 5-10 times more potent than CRF.