Effect of Angiotensin II on Vasopressin in Plasma and Platelets in SH and Wky Rats

Abstract

A study was carried out of the effects of iv angiotensin II on vasopressin release and the distribution of vasopressin between platelets and plasma in 12 week old conscious unrestrained SH and WKY rats. Angiotensin II was infused at rates of 31.25 to 500 ng/kg.min for 20 min. There was an enhanced pressor responsiveness to angiotensin II in the SH rats. Angiotensin II caused a moderate increase in plasma vasopressin concentrations, but only at doses which produced maximal pressor responses (250 to 500 ng/kg.min). There were no significant differences in vasopressin responses to angiotensin II in SH compared to WKY rats. Approximately 30% of circulating immunoreactive vasopressin was found in platelets in both SH and WKY rats, and this distribution was not greatly affected by the iv infusion of angiotensin II.

Key Words:

• Active renin
• Inactive renin
• Renovascular hypertension
• Molecular weight
• Gel filtration