Responses of active and inactive plasma renin to insulin-induced hypoglycemia in normal subjects

To examine the in vivo activation mechanism for the conversion of inactive to active renin in human plasma, we measured active, inactive and total plasma renin activity during an insulin tolerance test in normal subjects. Total renin was measured after trypsin activation of inactive renin. Inactive renin was calculated as the difference between total and active renin. With a decrease in the blood glucose level from 92 +/- 8 to 22 +/- 6 mg/dl (p less than 0.01), active renin increased significantly (p less than 0.01) from the basal level of 1.9 +/- 0.6 to 6.0 +/- 1.9 ng/ml.hr at 60 min after insulin injection. Total renin increased and inactive renin decreased slightly, but the changes were not statistically significant. The ratio of active to total renin showed a significant increase (p less than 0.01) at 60 min. These results suggest that stimulation of the endogenous sympathetic nervous system is involved in the in vivo activation of inactive renin.