Lack of inhibition of hog renin by heparin.

These experiments were performed to test if heparin inhibits the production of angiotensin I from rat renin substrate acted upon by either rat or hog renin. Substrate was prepared from the plasma of nephrectomized rats; commercially prepared hog renin and heparin (0-50 units/ml, final concentration) were added and angiotensin I production was measured by radioimmunoassay following incubation of the mixture at 37-38 degrees C for 30 min. Heparin had no effect on the radioimmunoassay for angiotensin I, nor on the Vmax nor the Km of the renin-renin substrate reaction. Heparin (0 and 50 units/ml, final concentration) was added to rat plasma which contained renin and renin substrate. No effect of heparin on the rate of production of angiotensin I was observed in this system. In conclusion, rat and hog renin are not inhibited by heparin within the range of concentrations used.