The effect of spironolactone on the elemental composition of the intraluminal fluids of the seminiferous tubules, rete testis and epididymis of the rat.

Embryologically, the epididymis and renal collecting tubules develop from the mesonephric duct. Aldosterone enhances the reabsorption of sodium from the collecting tubule, and there is evidence that sodium is removed from the epididymal lumen against a concentration gradient. Rats were treated with spironolactone, an aldosterone antagonist, and the concentrations of seven elements, including sodium, were measured in intraluminal fluids from the testis and epididymis. The sodium concentration in caput epididymidal fluid rose (102.5 +/- 4.4 to 128.0 +/- 6.8 mmol./l., p less than 0.01) after 14 days of spironolactone treatment. This finding is consistent with the hypothesis that aldosterone acts on the caput epididymidis, like the collecting tubule, to augment the removal of sodium from luminal fluid.