Abstract
In an attempt to classify physiological effect of L-sodium aspartate (aspartate) on renal function, the renal tubular potential was measured with rats kidney (distal tububule) by a micropuncture method before and after administration of aspartate (1mM /kg, i.v.). Four kinds of groups of experimental animals were used, i. e. 1) nomal control rats ; 2) adrenalecto-mized rats; 3) rats daily administered 600 mg. /kg, amphenone B for ten days ; 4) rats administered 5 uM/ kg, hydoroxylamine. The outline of the experimental results is as follows: - 1) The intracellular potential in the renal tubule of control rat was changed deeper (increase) by 10 mV than the control value, for a few hours after intravenous injection of aspartate (1 mM/kg. rat body weight). This potential change was demonstrated to be assosiated with an increase of intracellular K and a decrease of intracellular Na concentration. 2) The intrtacellular potential in the rat treated with amphenone B (600 mg. /kg. /day, orally, for ten days) and adrenalectomized rat was shallower than the control value and it could not be recovered by aspartate administration. 3) Hydroxylamine, a competitive inhibitor of the condensing enzyme of oxalacetic acid and acetyl CoA, lowered the intracellular potential, wihie aspartate administration could restore or even elevate it above normal value. 4) Other substrates such as oxalacetic acid, DL-di-sodium malate, and sodium pyruvate can also increase intracellular potential, while α-keogulutaric acid or L-sodium glutamate has little effect. These findings suggest that aspartate can exert its action in the presence of mineralcorticoid, and support the view that aspartate and its substrate group which increase the intracellular potential, may display their action in providing energy for the action of mineralcorticoid.
