HALL, JOHN E., ARTHUR C. GUYTON, NICK C. TRIPPODO, THOMAS E. LOHMEIER, ROBERT E. MCCAA, AND ALLEN W. COWLEY, JR. Intrarenal control of electrozyte excretion by angiotensin II. Am. J. Physiol. 232 (6): F53&F544, 1977 or Am. J. Physiol.: Renal Fluid Electrolyte Physiol. l (6): F53&F544, 1977.-The intrarenal role of angiotensin II in regulating renal blood flow and glomerular filtration rate, as well as water and electrolyte excretion, was examined in five normal and 17 sodium-depleted dogs. In the sodium-depleted dogs, intrarenal infusion of the competitive antagonist [Sar1, 11e8]-angiotensin II (0.25 pg/kg per min) elicited marked increases in renal blood flow, urine flow, urinary sodium, potassium, and osmolar excretion, smaller increases in glomerular filtration rate, and small but significant reductions in mean systemic arterial pressure. The rise in urinary sodium excretion from 0.087+ 0.02 during the control period to 0.380 t 0.110-meq/min per gram kidney wt after 90 min of antagonist infusion appeared to be due to the intrarenal effects of angiotensin II blockade, since there were no consistent changes in plasma aldosterone concentration during antagonist infusion. In a series of sodium-depleted dogs which served as a time control, there were no significant changes in any of the variables studied. Intrarenal infusion of the antagonist (0.25 yg/kg per mm) in normal dogs resulted in small but significant increases in renal blood flow and urinary sodium, potassium, and osmolar excretion. These data suggest that angiotensin plays an important role in regulating renal hemodynamics and electrolyte excretion, especially when the renin-angiotensin system is activated by sodium depletion. sodium depletion;[Sarl, Iles] angiotensin II; renal blood flow; glomerular filtration; sodium excretion

THERE IS SUBSTANTIAL EVIDENCE THAT the renin-angiotensin system plays an important role in the regulation of body fluid and electrolyte balance (7, 13, 25, 26). However, it is still not clear whether angiotensin II participates in this regulation primarily via its effects on aldosterone secretion or through its effects on renal hemodynamics.