Effect of prolonged lithium ingestion on the response to mineralocorticoids in rats

The effect of long-term lithium administration on the response to mineralocorticoids was studied in rats which were adrenalectomized in order to avoid the effects of endogenous hormone. The hormone response was estimated from the changes in urinary excretion of sodium and potassium in rats on low and high sodium intake and from the consumption of a hypertonic NaCl solution by rats given a free choice between this and demineralized water. Lithium was found to lower the response to aldosterone and deoxycorticosterone acetate both in acute and chronic experiments. It was further found that in adrenalectomized rats given no hormone, those given lithium consumed significantly more NaCl solution than those given no lithium. The experiments therefore provide evidence that lithium induces a sodium requirement beyond that induced by the inhibition of the response to mineralocorticoids.