Changes in Sodium and Water Excretion Produced by Vaso-Active and by Ganglionic and Adrenergic Blocking Agents

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Abstract
Nor-epinephrine has no direct effect on renal tubular absorption of Na. With a rate of infusion of this agent that produces a moderate elevation in blood pressure, excretion of water and electrolytes is augmented and usually there is an increased glomerular filtration rate and renal plasma flow. Increasing the blood pressure to about 170 mm. Hg usually results in a decreased rate of Na and urine output. At the same time renal plasma flow and the glomerular filtration rate are depressed. Aramine produces similar effects. Various ganglionic and adrenergic blocking agents (Hydergin excepted) failed to cause any consistent effect on either water or Na excretion. Changes in the rate of excretion of these substances during blockade almost invariably followed in the same direction as changes in renal hemodynamics. Isuprel and several N-sub-stituted arterenol derivatives, which are all vasodilators, did not modify water and Na excretion unless given in large enough amount to change renal hemodynamics. The data indicate that the absorptive capacity of the renal tubules are not directly influenced by sympathetic activity but only by the renal vascular changes produced by the latter.