Changes of renin isoelectric heterogeneity after acute and chronic stimulation of renin secretion

Changes in the multiple forms of renin secreted or stored in vitro by renal cortical slices were studied in rats made hypertensive with deoxycorticosterone, adrenalectomized rats, and rats fed a high or low salt diet. Renal slices from normal rats were also incubated with angiotensin II, vasopressin, and verapamil. Aliquots of incubation media were subjected to isoelectric focusing, and the six forms of renin were quantified and expressed as a percentage of the total renin activity recovered from the gel. The results showed that chronic and acute stimulation of renin secretion produced a similar modification of the isoelectric focusing profile, consisting of an increased proportion of renin forms with the more acidic isoelectric points. The change in the proportions of the more acidic renin forms was greater with chronic stimulation than that after stimulation with verapamil. However, chronic and acute inhibition or reductions of the rate of renin secretion did not modify the renin profile. We suggest that the progression in the shift of secreted renin forms to those with the more acidic isoelectric points correlates with the intensity or duration of stimulation of renin secretion. These data support the hypothesis that different pools of renin exist and are altered differently by chronic and acute stimulation of renin secretion.