The effects of combined renal vasodilatation and pressor agents on renal hemodynamics and the tubular reabsorption of sodium.

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Abstract
The combined effects of unilateral renal vasodilatation and angiotensin infusion on renal hemodynamics and Na excretion and reabsorption were studied in anesthetized hydropenic dogs. Unilateral renal vasodilatation alone with either acetylcholine, bradykinin, or kallidin resulted in an ipsilateral increase in renal plasma flow and an ipsilateral decrease in net tubular reabsorption of Na. The infusion of angiotensin or norepinephrine in the presence of unilateral renal vasodilatation resulted in a sustained marked increase in Na excretion and decreased Na reabsorption by the vasodilated kidney. These changes occurred in association with decreases in glomerular filtration rate (GFR), clearance of p-aminohippurate, renal plasma flow, and "noncortical" plasma flow. Sodium excretion usually decreased in control nonvasodilated kidneys during the infusion of angiotensin or norepinephrine, although GFR was often similar in the 2 kidneys. The clearance of p-aminohippurate, however, was always distinctly lower in the control nonvasodilated kidney. These results are consistent with the view that the proper combination of 2 physiologically impor-tent variables, arterial pressure and renal vascular resistance, can effect large changes in the tubular reabsorption of Na, probably through intrarenal mechanism.