PubMed1979
Inactive renin in human plasma is converted to active renin in vitro by acid activation or by cryoactivation. Renin activity was measured at pH 5.5 and renin concentration at pH 7.4. The plasma renin activity before and after cryo-treatment is termed active (APRA) and total (TPRA) plasma renin activity; the plasma renin concentration before and after acid treatment active (APRC) and total (TPRC) plasma renin concentration. In this study we demonstrated that in normal subjects the proportion of active to total renin after cryo-treatment averaged 61%, which was significantly (p less than 0.001) higher than the mean percentage active renin of 34 found with the acid activation procedure. Plasma angiotensin II correlated significantly with APRA, TPRA, TPRC and plasma angiotensin I (PA I), but not with inactive renin, which suggests that inactive renin does not produce angiotensin II in vivo. Cold treatment after acid activation and acid treatment after cryoactivation did not provoke a significant change in the measured renin concentration. Our data support the view that acidification of the plasma activates more than does cryo-treatment, and that inactive renin does not contribute to plasma angiotensin II.