Rat renal prorenin concentration in experimental hypertension

The amount of renal prorenin in models of hypertension in rats was studied by using a novel enzyme (PreR-Co). Ten microgrames of PreR-Co promoted a complete conversion of inactive renin, and during the first 15-min incubation the reaction was under initial velocity conditions. The enzyme-substrate reaction obeyed Michaelis-Menten kinetics, with a Vmax of 0.97 x 10(-5) pmol Ang I/min and a Km of 5.03 x 10(-5) pmol prorenin. The difference between the total renin concentration (TRC) and active renin concentration (ARC) in the normal rat kidney (356.4 +/- 20.6 and 105.3 +/- 7.6 ng Ang I/mg tissue/h respectively), indicated that inactive renin comprised 70% of TRC. In the aortic coarctation model, inactive renin comprised 68 % of TRC in the right kidney and no or very little prorenin was found in the left kidney. In the Goldblatt 2-kidney, 1-clip rats, the right kidney prorenin comprised 61% of the TRC and 54% in the clamped left kidney. After DOCA-Salt treatment prorenin was almost absent in the rat kidneys. In conclusion, we have developed an easy and sensitive method to measure inactive renin in the kidney that may be useful to study the biochemical events of renin maturation in physiological and pathological states.