Effect of high ambient temperature on the lipids and on the activity of enzymes of rat liver microsomes.

The work has been aimed at determining the content of cholesterol and selected phospholipids (phosphatidyl choline, phosphatidyl ethanolamine, phosphatidylserine, and phosphatidylinositol) in rats' liver microsomes subjected to single and repeated exposure to an increased ambient temperature. Simultaneously, under the same experimental conditions, NADH activities--cyt. c. reductase and glucoso-6-phosphatase-in liver microsomal fractions were determined. In the experiments--a thermal chamber with controlled temperature, continual airflow and controllable humidity coming to 47-65% was used. Rats were subject to 6-hr exposure to the temperature of 21 degrees C, 28 degrees C, and 35 degrees C singly or for 3 and 6 consecutive days. In the experimental arrangements applied, no significant changes in the content of test phospholipids and cholesterol were found. The slight increase in the PC/PE relation under the effect of 28 degrees C and 35 degrees C for 6 consecutive days was not statistically significant. Cholesterol content in rats subjected to 35 degrees C for 6 days, 6 hrs daily, was higher--compared to the control group exposed to 21 degrees C--by about 15%, this differences being not statistically significant, either. The activities of NADH: cyt. c. reductase and glucoso-6-phosphatase in result of rats' single, 3- or 6-fold exposure to an increased temperature exhibit a level approximating the activity of those enzymes in controls. The lowest activities were observed in rats subjected to 35 degrees C for 6 consecutive days, 6 hrs daily.(ABSTRACT TRUNCATED AT 250 WORDS)