WATER LOSSES INDUCED BY HEAT EXPOSURE AND THE KININ SYSTEM IN THE RAT

Normal Wistar rats, normal and kininogen-deficient Brown Norway rats were kept at ambiant temperatures of 26-degrees-C, 36-degrees-C or 40-degrees-C for 3 to 5 hours. Their colonic temperaturs and body weights were measured. At 26-degrees-C, the changes in these parameters were similar in the three strains. At 36-degrees-C, body weight loss was increased more in normal rats than in kininogen-deficient rats. At 40-degrees-C, body temperature increased more quickly and body weight loss was less enhanced in kininogen-deficient rats than in normal rats. The water content of muscles was less reduced in kininogen-deficient rats than in normal rats. HOE 140, a bradykinin antagonist, reduced the weight loss of Wistar rats kept at 36-degrees-C and 40-degrees-C. Atropine or removal of submaxillary glands increased colonic temperature and reduced the weight loss of Wistar rats at 36-degrees-C and 40-degrees-C. HOE 140 did not modify the reduction of weight loss induced by atropine but increased colonic temperatures and decreased thermal tolerance of atropinized Wistar rats at 36-degrees-C. These results indicate that the kallikrein-kinin system plays a role in salivary secretion and in heat exchange during a heat exposure.