Abstract
In order to investigate the dynamics of renin release in diabetes mellitus, the renin activity was measured in streptozotocin (30mg/kg and 60mg/kg)-induced diabetic rats in vivo (furosemide administration test) and in vitro (perfusion study of isolated rat kidney). In the in vitro tests, the kidney was perfused at 4.0ml/min for 20 min, and then the flow rate was decreased to 2.0ml/min for 10 min. The perfusate renin activity was measured by radioimmunoassay, using renin free plasma obtained from bilaterally nephrectomized rabbits as renin substrate. The basal and stimulated renin release from the isolated kidney of streptozotocin-induced diabetic rats were not different from those of control rats. In the in vivo experiments, the plasma renin activity (PRA) was measured before and after furosemide injection. The basal and furosemide-stimulated PRA levels were significantly lower in streptozotocin (60mg/kg)-induced diabetic rats than in controls and streptozotocin (30mg/kg)-induced diabetic rats.
These results suggest that the PRA level is decreased in severe diabetic rats due to secondary effects of diabetes on renin secretion, although the ability of the kidney to secrete renin is maintained.
