Dynamic responses of active and inactive renin and plasma norepinephrine during exercise in normal man.

Active and inactive plasma renin, plasma angiotensin II, and plasma norepinephrine were measured during graded exercise. Five health subjects exercised on bicycle ergometer at three different loads (50, 70, and 100% of maximal oxygen uptake). Active plasma renin and plasma angiotensin II were elevated significantly during graded exercise, but plasma inactive renin decreased during the heaviest exercise; the mean ratio of active renin to total renin increased from 57 to 92% after the heaviest load. Plasma norepinephrine was also elevated during graded exercise. There is a positive correlation between plasma norepinephrine and active plasma renin during graded exercise (r = 0.916, p less than 0.01). Similar norepinephrine and active renin responses to graded exercise suggest that the mechanism(s) for activation of inactive renin and the release of active renin from the kidney may be partially related to sympathetic nervous system activity.