Water metabolism of rats in the heat: dehydration and drinking

Publisher Website
Google Scholar
Abstract
Normal and desalivated rats were exposed to elevated ambient temperatures, and their thermal tolerance, evaporative water loss, tissue dehydration, and drinking were studied. At 40 C with no water available normal rats became hyperthermic (40-41 C) and increased evaporation by spreading saliva on their fur and skin. The saliva was initially derived from plasma, whose volume decreased by 11.3% in the 1st hr of exposure but was subsequently maintained by losses from other tissues. Evaporation continued for 3-5 hr, until heat exhaustion occurred. At this time plasma volume fell precipitously and body temperatures rose to lethal levels. Adequate evaporation was thus prerequisite for survival, and some rats which did not spread saliva were intolerant to heat stress. When water was available, normal rats showed increased drinking with increasing temperatures, and their intakes approximated their losses. Intravascular and intracellular dehydration secondary to salivary water loss appeared to be the necessary stimulus for drinking in the heat. Desalivated rats, which could not spread saliva, did not become dehydrated in the heat and did not drink, despite severe hy-perthermia and a dry mouth.

This publication has 11 references indexed in Scilit: