Regulation of sodium chloride intake by rats

Abstract

Regulation of NaCl intake was studied in rats by allowing them choice between distilled water and a NaCl solution to drink during experiments in which food was loaded with NaCl to levels of 6% by weight. The level of dietary NaCl failed to influence spontaneous intake of NaCl solutions but increased water intake in proportion to the concentration of NaCl in food. Increases in the concentration of NaCl solution offered to rats whose food was salt loaded resulted in proportional decreases in volume intake of NaCl solution such that total amount of sodium ingested by way of NaCl solution was maintained at 1.3–1.5 mEq/100 g body wt per day. The results suggest, but do not prove, that NaCl intake is "regulated" by way of NaCl in solution rather than by way of NaCl in food. The mechanism regulating NaCl intake is separate from that regulating water intake and appears to be located somewhere within either the mouth or pharyngeal region or both. Bypass of these regions by intraperitoneal injection of saline failed to alter the pattern of spontaneous NaCl intake of rats.