THE EFFECT OF MERCURIAL DIURETICS ON RENAL AMMONIA AND TITRATABLE ACIDITY PRODUCTION IN ACIDOTIC HUMAN SUBJECTS WITH REFERENCE TO SITE OF DIURETIC ACTION 1

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Abstract
To determine whether mercurial diuretics affect renal distal tubular function in man, the effect of Thiomerin and Mercuzanthin on 2 active distal mechanisms[long dash]ammonia and titratable acidity production[long dash]was studied in patients subjected to NH4Cl acidosis. The mercurials had no effect on ammonia secretion. However, during diuresis there was increased titratable acidity production, probably resulting from greater load of phosphate and other buffers delivered to the distal tubule, secondary to mercurial inhibition of proximal tubular reabsorption. When the distal load of phosphate was increased by infusing buffer Na phosphate, mercurial still produced increased titratable acidity production which was again paralleled by augmented phosphate excretion. To determine if increased Na load might similarly augment ammonia production, admn. of the mercurial was preceded by rapid infusion of hypertonic saline. No significant change in ammonia or titratable acidity production is observed, but with maximal diuresis urinary water, Na and Cl excretions were 33%, 34% and 39% of the corresponding amts. filtered, and there was a decrease in concn. of urinary electrolytes. The data are discussed in relation to the site and mechanism of action of mercurial diuretics in man. It is suggested that the diuretic action of mercurials is exerted chiefly on the proximal tubules and that although these diuretics may also act on the distal tubules, such effect on distal tubular function remains to be established.