No Evidence of Active Renin-Inhibitors in Plasma. The Kinetics of the Reaction between Renin and Substrate in Non-pre-treated Plasma

Abstract

In untreated plasma with the whole peptidase activity intact, the reaction between renin and its substrate was determined, using radioimmunoassay. The rate of reaction was determined by measuring the rate of endogenous substrate consumption with time, as renin and renin-substrate were shown to be stable. By adding small physiological amounts of purified renal rat renin, the reaction rate was determined in untreated plasma and serum from normal, salt-depleted, 24-hour and 48-hour nephrectomized, and experimentally hypertensive rats. The reaction rate varied with the reninsubstrate concentration, according to Michaelian kinetics, but there was no evidence of inhibitors or activators of the reaction between renin and reninsubstrate.

Key Words:

• Angiotensin-I
• Angiotensin-II
• converting enzyme
• enzyme assay
• enzyme kinetics
• plasma renin activity
• plasma renin concentration
• radioimmunoassay
• renin-inhibitor
• renin-substrate