[Changes in angiotensinogen and des-angiotensin I-angiotensinogen in man and rat upon inhibition of converting enzyme].

The effects of converting enzyme inhibition on plasma renin substrate concentration were studied in man and rat. This study use new direct radioimmunoassays of angiotensinogen completing the classical enzymatic methods. In human investigation converting enzyme is inhibited after Captopril treatment. Our results demonstrated that resulting increase of plasma renin concentration enhanced the consumption of renin substrate as shown by the fall of angiotensinogen levels measured by indirect method. In the rat, we observed the same drop of renin substrate during MK421 administration. The fall of angiotensinogen levels, measured by indirect method, was not in agreement with results of direct radioimmunoassay. This discrepancy can be explained by the accumulation of des-angiotensin I-angiotensinogen in plasma. These modifications are potentiated by sodium depletion.