Intravenous hypertonic saline injections and drinking in domestic fowls

Fowls were given intravenous (IV) injections of hypertonic solutions of NaCl, and subsequent water intakes were recorded. All concentrations of hypertonic NaCl increased drinking in the 90 min after injection, compared with control treatments. Increments in drinking in this time agreed closely with calculated amounts required to restore normal osmolality. In further experiments, delaying access to water by periods of 60-360 min after injection failed to reduce drinking elicited by hypertonic NaCl. Injections of 2.0 M NaCl caused increases in plasma osmolality and sodium concentration which were maintained throughout 360 min water deprivation, and caused prolonged reductions in hematocrit and plasma protein concentrations. These results demonstrate that cellular dehydration is a potent thirst stimulus in fowls, and imply that fowls do not reduce hyperosmolality by excretion of salt when water is unavailable.