[Effect of 1 alpha-hydroxycholecalciferol on cellular calcium metabolism of kidney cortex (author's transl)]

Rats were provided a normal laboratory diet or a low Ca.vitamin D-deficient diet. After the administration of 1 alpha-hydroxycholecalciferol, mitochondria, microsomes and slices were prepared from kidney cortex of both control and treated rats. When 1 alpha-hydroxycholecalciferol was given to normal and low Ca.vitamin D-deficient rats, Ca accumulation in mitochondria was stimulated during 30 minutes and the high calcium content was maintained at the subsequent incubation. There was a significant decrease of mitochondrial Ca2+-ATPase and Mg2+-ATPase activities with low Ca.vitamin D depletion, but both enzyme activities were restored by 1 alpha-hydroxycholecalciferol treatment of the depleted rats. Ca2+-ATPase and Mg2+-ATPase activities of microsomes were not altered with the administration of 1 alha-hydroxycholecalciferol. In contrast to results of mitochondrial Ca transport, changes in Ca influx and efflux of slices were not significant in response to the treatment of low Ca.vitamin D-deficient rats with 1 alpha-hydroxycholecalciferol. The results of the present study suggest that 1 alpha-hydroxycholecalciferol plays a role in the process of Ca accumulation and ATP hydrolysis of mitochondria in kidney cortex.