Diuresis in Newborn Rat Given Intravenous Water or Salt Solution. ∗

Summary

1. The newborn rat shows diuresis when given 1 M NaCl solution by vein. The urine output in 2 hours is 6-fold that after administration of either intraperitoneal or intragastric fluid. 2. Water by vein induces twice as much diuresis as does water by other routes. 3. Plasma and urine chloride concentrations change equally, regardless of route of fluid administration; only time relations differ with route. 4. When newborn rats are not allowed to suckle, saline diuresis is 3-fold that in suckled litter-mates. 5. Controllable factors therefore determine whether water or salt shall arouse diuresis on the day of birth.