Activity of rat blood cholinesterases following exposure of the animals to increased environmental temperature.

The acetylcholinesterase activity of erythrocytes was investigated and compared with cholinesterase activity of the blood plasma in rats exposed to elevated temperature of the environment. The rats were kept in a thermic chamber with regulated temperature, forced air flow and controlled moisture of 55-19%. The applied temperatures were 21 degrees C (control) and 28 degrees C or 37 degrees C. The rats were exposed once for 3, 6, 12 or 24 hours and repeatedly for six successive days, for six hours each day. Experiments were also performed to find whether previous exposure of the rats to raised temperature "sensities" acetylcholinesterase to the action of typical cholinesterases inhibitor (DFP). Arrhenius plots were determined for erythrocyte acetylcholinesterase of rats subjected for 6 hours to raised temperature. It was found that the activities of both enzymes undergo only slight changes in dependence on the temperature applied and the time of exposure. More pronounced changes in this activity were observed when the rats were subjected to 37 degrees C. This may have been connected with disturbance of the lipoprotein structure and with an increase of osmotic fragility of the erythrocytes. It was also noted that earlier exposure of the animals to raised environmental temperature "sensitises" the acetylcholinesterase of the erythrocytes to the action of the organophosphorus inhibitor in vivo.