Mukherjee et al conducted a study in which chicks were raised for 3 to 4 weeks either on a normal (vitamin D supplemented) or a rachitogenic diet. The Ca2+ content of the serum, heart tissue and heart mitochondria was significantly decreased in chicks raised on a rachitogenic diet. In mitochondria isolated from calcium deficient hearts, the rate of adenosine diphosphate induced state 3 respiration and 2,4-Dinitrophenol uncoupled respiration were significantly decreased.When vitamin D deficient chicks were orally dosed with vitamin D3, serum calcium level and state 3 respiration rate returned to normal indicating that the above changes are reversible In a longitudinal study, the effects of cholecalciferol therapy on skeletal mitochondrial oxidative function in vitamin D deficient subjects using 31Phosphorus magnetic resonance spectroscopy were examined.The phosphocreatine recovery half-time (t1/2PCr) 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).