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.