Influence of endothelin on systemic arterial pressure and regional blood flow in the cat

Regional vascular responses to endothelin were investigated in the anesthetized cat. I.v. injection of endothelin at 0.1 nmol/kg decreased arterial pressure and renal vascular resistance but increased vascular resistance in the small intestine. At 0.3 nmol/kg i.v. the peptide caused a greater decrease in arterial pressure and increased mesenteric resistance but had no significant effect on renal resistance. In contrast, at 1 nmol/kg i.v. endothelin caused a biphasic change in arterial pressure and marked in mesenteric and renal resistance. Injection of the peptide in doses of 0.1 - 1 nmol/kg i.v. caused only increases in carotid blood flow. These data suggest that responses to endothelin are dependent on dose and vascular bed studied.