Effect of ACTH administration on the haemodynamic response to arginine-vasopressin in sheep

1. Blood pressure, heart rate and cardiac output were studies in intace conscious sheep during AVP infusion at 0.1, 0.25, 0.5 and 1.0 microgram/min for 30 minutes to determine whether pressor responsiveness to AVP was altered in ACTH-induced hypertension. 2. Prior to ACTH treatment, AVP produced rises in blood pressure associated with a fall in heart rate and cardiac output. 3. During ACTH treatment, pressor responsiveness to AVP and decrease in cardiac output were unchanged, but reflex bradycardia was reduced. 4. ACTH-induced hypertension in sheep is not associated with enhanced pressor responsiveness to AVP.