The Effect of High Environmental Temperature and Exercise on the Metabolism of Ascorbic Acid in Rats

Abstract

The effects of high environmental temperature and exercise on the ascorbic acid metabolism in rats were studied. The heating and exercise gave stressful effects on the animals, i.e., after the exposure to six hours of heating or 30 minutes of forced swimming exercise for four consecutive days, the wet weights of spleen and thymus were reduced, while the serum adrenocorticoid levels increased compared with the control group. The concentration of ascorbic acid in serum, thymus, and spleen significantly decreased in both heat-treated and exercised groups. There was a negative correlation between ascorbic acid and adrenocorticoid levels in the adrenals. The L-gulonolactone oxidase activity increased significantly in the liver microsomal fraction in both groups, accompanied by an increase in the V_<max> but without any changes in the K_m. These results suggest that the consumption of ascorbic acid in the rats was increased by the stressful conditions of heating and exercise, which provoked the increased biosynthesis of the vitamin.