Body water distribution after intracerebroventricular injection of NaCl in rats

The aim of the investigation was to evaluate the effects of the intracerebroventricular (ICV) injection of 0.1 ml of 1 M NaCl, on the body water distribution in nephrectomized male rats. In comparison with the control rats injected with an equal volume of isotonic saline, the ICV injection of 1 M NaCl elicited 90 min later a significant increase of plasma volume whereas the total water, the inulin space, the calculated interstitial space and the intracellular water were not altered. The increase of plasma volume could be explained by a decrease of capillary efflux to the interstitial space. These results suggest that the ICV injection of 1 M NaCl releases a substance which could regulate the plasma volume.