phosphocreatine and Vitamin-D-Deficiency

Topics: Actomyosin; Adenosine Triphosphate; Animals; Cell Membrane; Creatine; Creatine Kinase; Energy Metabolism; Humans; Hyperparathyroidism, Secondary; Muscles; Muscular Atrophy; Oxidative Phosphorylation; Oxygen Consumption; Phosphocreatine; Rabbits; Rats; Troponin; Troponin C; Uremia; Vitamin D Deficiency

There are several published reports on the prevalence of low vitamin D levels in otherwise healthy Indian population. Vitamin D deficiency has shown variable effect on muscle performance and strength but there is paucity of data on the effect of vitamin D deficiency on muscle energy metabolism. The present study was proposed to investigate the influence of severe vitamin D deficiency on high-energy metabolite levels in resting skeletal muscle and thereafter, monitor the response after vitamin D supplementation using ³¹P magnetic resonance spectroscopy (MRS). Study was conducted on 19 otherwise healthy subjects but with low serum 25(OH)D levels (<5 ng/ml). Subjects were supplemented with cholecalciferol at a dose of 60,000 IU/week for 12 weeks. MRS measurements of inorganic phosphate (Pi), phosphocreatine (PCr), phosphodiester (PDE) and ATP of the calf muscle were taken pre- and post-vitamin D supplementation. The study revealed significantly increased PCr/Pi ratio and decreased [Pi] and PDE/ATP ratio with raised serum 25(OH)D levels after 12 weeks of supplementation. The study indicates that serum 25(OH)D level plays an important role in improving the skeletal muscle energy metabolism and vitamin D deficiency might be one of the primary reasons for prevalence of low PCr/Pi ratio and high PDE values in normal Indian population as reported earlier. The findings of this preliminary study are highly encouraging and warrant further in-depth research, involving larger number of subjects of different age groups, regions and socio-economic sections of the society to further strengthen a correlation between vitamin D levels and muscle energy metabolism.

Topics: Adenosine Triphosphate; Adolescent; Adult; Calcifediol; Cholecalciferol; Dietary Supplements; Energy Metabolism; Female; Humans; Hyperparathyroidism, Secondary; India; Magnetic Resonance Imaging; Male; Muscle, Skeletal; Phosphocreatine; Phosphoric Diester Hydrolases; Phosphorus Isotopes; Pilot Projects; Severity of Illness Index; Vitamin D Deficiency; Whole Body Imaging; Young Adult

Suboptimal mitochondrial function has been implicated in several disorders in which fatigue is a prominent feature. Vitamin D deficiency is a well-recognized cause of fatigue and myopathy. The aim of this study was to examine the effects of cholecalciferol therapy on skeletal mitochondrial oxidative function in symptomatic, vitamin D-deficient individuals.. This longitudinal study assessed mitochondrial oxidative phosphorylation in the gastrosoleus compartment using phosphorus-31 magnetic resonance spectroscopy measurements of phosphocreatine recovery kinetics in 12 symptomatic, severely vitamin D-deficient subjects before and after treatment with cholecalciferol. All subjects had serum assays before and after cholecalciferol therapy to document serum 25-hydroxyvitamin D (25OHD) and bone profiles. Fifteen healthy controls also underwent (31)P-magnetic resonance spectroscopy and serum 25OHD assessment.. The phosphocreatine recovery half-time (τ1/2PCr) was significantly reduced after cholecalciferol therapy in the subjects indicating an improvement in maximal oxidative phosphorylation (34.44 ± 8.18 sec to 27.84 ± 9.54 sec, P < .001). This was associated with an improvement in mean serum 25OHD levels (8.8 ± 4.2 nmol/L to 113.8 ± 51.5 nmol/L, P < .001). There was no difference in phosphate metabolites at rest. A linear regression model showed that decreasing serum 25OHD levels was associated with increasing τ1/2PCr (r = -0.41, P = .009). All patients reported an improvement in fatigue after cholecalciferol therapy.. Cholecalciferol therapy augments muscle mitochondrial maximal oxidative phosphorylation after exercise in symptomatic, vitamin D-deficient individuals. This finding suggests that changes in mitochondrial oxidative phosphorylation in skeletal muscle could at least be partly responsible for the fatigue experienced by these patients. For the first time, we demonstrate a link between vitamin D and the mitochondria in human skeletal muscle.

Topics: Adolescent; Adult; Cholecalciferol; Fatigue; Female; Humans; Longitudinal Studies; Magnetic Resonance Spectroscopy; Male; Middle Aged; Mitochondria; Muscle Cramp; Muscle, Skeletal; Oxidative Phosphorylation; Phosphocreatine; Phosphorus Isotopes; Treatment Outcome; Vitamin D Deficiency; Vitamins; Young Adult

The effects of vitamin D deprivation on the chick heart were investigated from three aspects: cardiac contractility (+/- dP/dT), intracellular high-energy phosphorus compounds, and structural differences. Four-week-old vitamin D-deficient chicks were divided into four groups: Group A served as the normal group and received subcutaneous injections of cholecalciferol; Groups B and C were vitamin D-deficient hearts but perfused differently; Group D received daily subcutaneous injections of 5 micrograms of 1,25(OH)2D3. When the isolated spontaneously beating hearts (modified Langendorff preparation) were perfused with Krebs-Henseleit (KH) solution containing a calcium concentration of 2.5mM, the myocardial contractility of the vitamin D-deficient hearts was significantly increased when compared with group A. After the isolated heart had beaten for one hour, the myocardial contractility in the vitamin D-deficient hearts was found to decline to significantly lower values. Presacrifice administration of 1,25(OH)2D3 improved cardiac performance. Vitamin D deficiency resulted in an enhanced rate of decline of the intracellular high-energy phosphorus compounds. No differences were found in the microscopic study. These observations suggest that vitamin D has a role in cardiac function.

Topics: Adenosine Triphosphate; Animals; Body Weight; Calcium; Chickens; In Vitro Techniques; Magnetic Resonance Spectroscopy; Myocardial Contraction; Myocardium; Organ Size; Phosphocreatine; Phosphorus; Vitamin D Deficiency

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.

Topics: Animals; Body Weight; Calcium; Cholecalciferol; Insulin; Male; Muscle Proteins; Muscles; Phosphocreatine; Rats; Rats, Inbred Strains; Vitamin D Deficiency