The effect of cholecalciferolin vivo on proteins and lipids of skeletal muscle from rachitic chicks

Abstract

The protein and lipid constituents of skeletal muscle subcellular fractions isolated from chicks fed a vitamin D-deficient diet for 3 weeks and chicks replated with cholecalciferol (vitamin D3) were analyzed. Administration of the sterol markedly altered the protein composition of mitochondria. The changes were localized in the inner membranes and consisted of a modification of the relative amounts of proteins of approximate mol wt of 83,000, 58,000, 42,000, and 34,000. In addition, treatment with vitamin D3 modified the distribution pattern of components of the actomyosin contractile complex. An increase in actin and troponin C was particularly noticeable. No differences between rachitic and treated animals were detected in the protein composition of sarcoplasmic reticulum membranes and postmicrosomal soluble fraction. A significant increase in the phospholipid content of sarcoplasmic reticulum (P less than 0.05), and to a lesser extent of mitochondria, was observed in repleted chicks. The relative proportions of individual phospholipids, however, were not changed. Injection of an acute dose of cholecalciferol to chicks less severely depleted in vitamin D significantly stimulated the incorporation of 32PO4 in vivo to muscle homogenates, mitochondria, and sarcoplasmic reticulum (P less than 0.05). As the increases in specific activities of sarcoplasmic inorganic P and membrane lipid P were similar whereas that of serum remained unchanged, the results are compatible with the idea that vitamin D3 stimulates phosphate fluxes across muscle membranes. The sterol produced minor modifications in the fatty acid composition of sarcoplasmic reticulum (P less than 0.05).

Role of Vitamin D in Skeletal Muscle Function*

“…However, administration of the sterol results in a marked alteration of the protein composition of mitochondria. These changes are localized in the inner membranes and consist in a decrease of the relative amounts of proteins of approximate mol wts of 83,000 and 58,000, accompanied by an increase of proteins with approximate mol wts of 42,000 and 34,000 (70). In general agreement with these observations, it has been shown that vitamin D stimulates in vivo [ 3 H]leucine labeling of total mitochondrial proteins (71).…”

“…In addition, it has been shown that SR membranes from vitamin D-repleted animals contain higher relative amounts of phospholipid than animals deficient in the sterol. However, no changes in phospholipid composition were detected between both experimental groups (70). The role of the vitamin Ddependent increase in SR phospholipid content in changes in SR Ca transport induced by the sterol is not known.…”

“…Decreased Ca uptake in skeletal muscle SR vesicles isolated from vitamin D-deficient or strontium-fed chicks and uremic rabbits is not accompanied by major alterations in the relative amounts of the Ca-transport ATPase and Ca-binding proteins as revealed by polyacrylamide gel electrophoresis (65,66,70). Similarly, the stimulation of sarcolemmal Ca transport caused by vitamin D treatment of chicks raised on a diet depleted of vitamin D could not be correlated to modifications in the electrophoretic protein profile of the membrane (21).…”

Dietary Vitamin D3 Supplementation at 10× the Adequate Intake Improves Functional Capacity in the G93A Transgenic Mouse Model of ALS, a Pilot Study

“…It is possible that the HiD diet in our study attenuated the disease-induced rapid decline in muscle function and strength by modulating the mechanisms involved in contractile protein synthesis and energy homeostasis. Indeed, vitamin D 3 and/or its metabolites increase troponin C [39], mediate protein synthesis and cellular ATP stores [40], and increase actin and sarcoplasmic protein expression [41] in striated muscle. Vitamin D 3 supplementation above the adequate intake may be a potential therapeutic in disease states involving loss of motor neuron stimuli to voluntary muscles or loss of muscle mass and function due to immobilization, disuse, cachexia, sarcopenia, or neuromuscular disease.…”

Relationship Between Vitamin D and Muscle Size and Strength in Patients on Hemodialysis

“…At the cellular level, vitamin D deficiency impairs intracellular calcium kinetics and muscle cell contractility [8,9], mitochondrial metabolism [10,11] and protein synthesis [12,13]. Treatment with vitamin D corrects these impairments [14,30] as well as restoring strength and improving balance in vitamin D deficient humans [16,29,31]. Despite the fact that vitamin D deficiency is associated with muscle loss [12,13] and weakness [16,28,29], which may contribute to the significant muscle atrophy, weakness, and widespread disability experienced by patients with ESRD, the current focus of vitamin D treatment for the control of SHPT, as outlined in the current K/DOQI guidelines [5], is on measuring its effects on bone metabolism and tissue calcification.…”