Vitamin D Deficiency, hypocalcemia, and increased skeletal muscle degradation in rats.
The myopathy associated with vitamin D deficiency was examined in vitamin D-deficient and vitamin D-supplemented rats. When compared with either vitamin D-supplemented ad lib. or pair-fed rats, weight gain and muscle mass were decreased in vitamin D-deficient hypocalcemic animals. With the exception of a modest decrease in muscle creatine phosphate levels, muscle composition was unchanged by vitamin D deficiency. Muscle protein turnover rates were determined in both in vivo and in vitro studies and demonstrated that myofibrillar protein degradation was increased in vitamin D deficiency. Normal growth rates could be maintained be feeding the rats vitamin D-deficient diets containing 1.6% calcium, which maintained plasma calcium within the normal range. In addition to its role in maintaining plasma calcium, vitamin D-supplemented rats had significantly higher levels of the anabolic hormone insulin. Vitamin D supplementation may affect muscle protein turnover by preventing hypocalcemia, as well as directly stimulating insulin secretion, rather than by a direct effect within skeletal muscle.
D000818:Animals; D001835:Body Weight; D002118:Calcium / Q000097:blood* / Q000652:urine; D002762:Cholecalciferol / Q000627:therapeutic use; D007328:Insulin / Q000097:blood; D008297:Male; D009124:Muscle Proteins / Q000378:metabolism; D009132:Muscles / Q000378:metabolism*; D010725:Phosphocreatine / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D014808:Vitamin D Deficiency / Q000188:drug therapy / Q000378:metabolism*
D007328:Insulin; D009124:Muscle Proteins; D010725:Phosphocreatine; D002762:Cholecalciferol; D002118:Calcium