Plasma renin activity following central infusion of angiotensin II and altered CSF sodium concentration in the conscious goat.

To study central influences on the renal release of renin, angiotensin II was infused into the lateral cerebral ventricle of conscious hydrated goats. CSF sodium concentrations was increased or lowered by similar infusions of hypertonic NaCl or of isotonic fructose solution. Infusion of angiotensin II in doses from 0.5 to 1 mug caused a drop in plasma renin activity (PRA) and elicited a rise in blood pressure, antidiuresis, natriuresis, and thirst. Intraventricular infusion of hypertonic NaCl also supressed PRA, induced antidiuresis, natriuresis, and an inconsistent rise in blood pressure. Lowering of CSF [Na+] by infusion of isotonic fructose caused a rise in PRA and was followed by a water diuresis in the non-hydrated animal. The fructose infusions caused some decrease in renal K+ excretion but no consistent change in renal Na+ excretion. The results indicate that angiotensin II and changes in sodium balance modulate renal renin release also via the central nervous system.