Effects of sodium intake and Goldblatt hypertension on renin release in rat kidney slices.

The effects of altering sodium intake and inducing two-kidney, one-clip Goldblatt hypertension in the male Sprague-Dawley rat on renin release (RR) from renal cortical slices were examined. The low sodium diet significantly elevated plasma and kidney renin activity (KRA) and base-line renin release (BRR). KRA and BRR in the unclipped kidney of Goldblatt hypertensive rats were suppressed; KRA and BRR in the contralateral clipped kidney were comparable to values in normotensive animals fed a basal diet. Regression analysis of BRR vs. KRA for all kidneys studied yielded an r value of 0.728 for a linear model (y = a + bx) and 0.831 for a power model (y = axb), indicating that BRR is dependent on renal renin stores over a wide range of KRA, and suggesting that BRR may reach a maximal value. Percent inhibition of RR by angiotensin II (AII) and percent stimulation of RR by isoproterenol were the same in high, low, and basal salt states, while absolute changes in RR and changes in RR expressed as percent of renin stores released per hour were less in the high salt state, suggesting that isoproterenol-induced stimulation and AII-induced inhibition of RR are dependent on renal renin stores.