Effect of 1,25-dihydroxycholecalciferol on sarcoplasmic reticulum calcium transport in strontium-fed chicks.

Feeding of chicks with strontium, an inhibitor of 1,25-dihydroxycholecalciferol synthesis in kidney, during 7 days, significantly depressed the initial rate of calcium uptake and calcium storing capacity of sarcoplasmic reticulum membranes from skeletal muscle. Oral administration of 1,25(OH)2D3 to strontium-fed animals returned calcium transport values to normal. The changes observed could not be related to differences in the relative proportions of transport ATPase and calcium binding proteins. The results are consistent with a role of 1,25(OH)2D3 in muscle function.