The Influence of Ouabain on in Vitro Renin Secretion

Using rat kidney cortex slices, in vitro renin secretion was measured as a function of sodium concentration of the incubation medium. We found, as have many others previously, that renin secretion increases with increasing medium sodium concentration. However, in the presence of 10−3M ouabain, renin secretion decreased with increasing medium sodium concentration. Since others have shown that intracellular sodium concentration varies directly with medium sodium concentration in the presence of ouabain, it seems unlikely that these results can be explained by a single unifying hypothesis, such as that renin secretion is inversely related to intracellular sodium concentration.