No evidence for the existence of a species-specific renin substrate in plasma from normal and bilaterally nephrectomized rats.

Renin substrate in plasma from normal and biolaterally nephrectomized rats was measured using an excess of rat or rabbit renin which had the same pressor activity when directly assayed in the rat. The amounts of angiotensin I generated with an excess of rat renin were similar to those generated with an excess of rabbit renin in plasma from normal and bilaterally nephrectomized rats. Further addition of an excess of homologous renin to the incubation mixture did not generate more angiotensin I from normal and bilaterally nephrectomized rat plasma which had been incubated before with an excess of rabbit renin. The isoelectric focusing profiles of plasma renin substrate from normal and bilaterally nephrectomized rats were almost identical using an excess of either rat or rabbit renin. It is concluded that there is no species-specific renin substrate for homologous renin in normal or bilaterally nephrectomized rats.