ADDITION OF THE SALURETIC ACTION OF FUROSEMIDE TO THE SALURETIC ACTION OF CERTAIN OTHER AGENTS

¹ Department of Pharmacology, College of Medicine, State University of Iowa, Iowa City, Iowa

During maximal diuresis produced by hydrochlorothiazide, addition of furosemide produced a diuretic-saluretic response significantly greater than that produced by hydrochiorothiazide alone. However, this response was less than additive. During maximal furosemide diuresis, hydrochlorothiazide was without effect. It would appear that these structurally similar compounds affect sodium reabsorption by a common mechanism of action. In addition, however, furosemide is also capable of inhibiting the reabsorption of sodium by a different mechanism or at a different site than does hydrochlorothiazide.

During maximal mercurial diuresis, a significantly greater per cent of filtered sodium was excreted following furosemide. This suggests that furosemide inhibits renal sodium transport, at least in part, in a different manner from chlormerodrin. The maximal diuresis produced by furosemide was diminished following the intravenous administration of chlormerodrin.

Furosemide was without effect in dogs receiving a maximally effective dose of ethacrynic acid and, conversely, ethacrynic acid was without effect during maximal furosemide diuresis. These observations suggest that these agents, though chemically unrelated, share a common mechanism or site of action along the nephron.