Sodium appetite induced in rats by chronic administration of a thiazide diuretic

Characteristics of hydrochlorothiazide (HCZ)-induced sodium appetite were examined in rats fed with low sodium diet to which HCZ was added. Compared with controls, HCZ induced a robust appetite for 0.1 and 0.3 M NaHCO3. The intake of 0.3 M NaCl was only about one half that of NaHCO3, but was still greatly above control. In both cases, the intake of the sodium solution exceeded that of water, so the rats were taking a hypertonic mixture. The appetite was evident in both Sprague-Dawley and Long-Evans rats, but appeared to be more stable in the latter strain over at least 1 month. The diuretic and natriuretic effect of HCZ was sustained over this period. Plasma renin activity was elevated substantially in HCZ-treated rats, but aldosterone concentration was decreased. Administration of HCZ in food is a simple and reliable method for inducing a sustained, substantial, and need-based salt appetite in rats.