Effects of polyethylene glycol on water and saline intake in the Mongolian gerbil

To establish the water balance regulatory ability of gerbils in response to a hypovolemic dipsogen, adult female gerbils (50-70 g) were injected subcutaneously with either a .9% NaCl vehicle or 10% or 30% (wt/vol) polyethylene glycol (mol wt 20,000). At each injection level one-half of the Ss had access to water, the other to .9% NaCl after injection. There was a significant increase in fluid intake associated with injection doses and Ss drank significantly more when allowed saline to drink rather than water. In Experiment II under a similar set of manipulations, hematocrit values were obtained at 12 and 24 hours after injection and showed decreasing blood volume levels which apparently served as the thirst stimulus. The results were discussed in terms of the voluntary dehydration findings of Stricker on rats and thus demonstrated the similarity of gerbils and rats in response to extracellular insult.