Abstract
Five experimental groups with five adult male rats in each, were exposed to 20, 35, 40 and $45^{\circ}C$ air temperature for 50-70 minutes, and to $50^{\circ}C$ for 30-50 minutes, respectively. Food and drinking water were not permitted during the exposure. Blood samples were obtained by heart puncture immediately after the thermal treatment. All the rats were hyperthermic (p<0.01) as compared to the controls ($20^{\circ}C$). Hyperthermia was associated with hypoglycemia which was significant (p<0.01) at 45 and $50^{\circ}C$ exposures. Plasma levels of GOT and GPT declined at 35 and $40^{\circ}C$ reaching the lowest (p<0.05) level at $45^{\circ}C$, while at $50^{\circ}C$ GOT level was elevated by 45% but GPT was normal as compared to the controls. Differences between groups were significant (p<0.01) for GOT and insignificant for GPT. Hematocrit value increased significantly (p<0.01) at 45 and $50^{\circ}C$, indicating hemoconcentration. It could be concluded that severe heat stress (45 and $50^{\circ}C$) resulted in critical hyperthermia, hypoglycemia, disturbed liver function, body dehydration, and hemoconcentration leading to death.