Influence of EGTA on an exercise-induced elevation in the colonic temperature of the rat.

The purpose of this study was to determine if an exercise-induced rise in body temperature could be affected by the chelation of Ca++ in the extracellular fluid surrounding the hypothalamus of the rat. Following the implantation of a guide tube above the hypothalamus, each animal was familiarized with exercising on a motor-driven treadmill. In random order, on separate days, a solution containing 3.6 mM EGTA, 26 mM Ca++ or an artificial cerebrospinal fluid (ACSF) solution was perfused through the guide tube while the animal was running. Colonic (Tc) and tail-skin (Tt) temperatures were monitored continuously. The perfusion of EGTA produced a significant increase in Tc when compared with the perfusion of the ACSF solution. The perfusion of excess Ca++ produced a significant decrease in Tc. These results suggest that Ca++ may play an important role in the mediation of heat dissipation during exercise.