ABSTRACT
Severe hypokinesia of rats given the diet with a ratio of Ca:P = 1:0.5-1:3 was accompanied by hypocalcemia, development of osteoporosis, and some intensification of renal calcinosis. The decrease of phosphorus consumption (Ca:P = 1:0.5-1:1) prevented a development of these changes in intact animals and increased bone mineralization in hypokinetic ones. Excessive phosphorus consumption (Ca:P = 1:3) produced hypocalcemia, hyperphosphatemia, and some osteoporotic changes in the bones of intact animals and intensified these changes with hypokinesia. Administration of 24,25-dihydroxycholecalciferol, an active metabolite of vitamin D3, at a dose of 1.25 micrograms/d prevented a development of bone disorders, thus effectively stimulating diaphyses and epiphyses mineralization and correcting hypocalcemia in hypokinetic rats. 24,25(OH)2D3 at the same dose did not intensify nephocalcinosis and produced no toxic symptoms with hypokinetic animals.
Subject(s)
Diet , Dihydroxycholecalciferols/therapeutic use , Hypocalcemia/drug therapy , Phosphorus/administration & dosage , 24,25-Dihydroxyvitamin D 3 , Alkaline Phosphatase/blood , Animals , Bone Diseases/drug therapy , Bone Diseases/etiology , Bone and Bones/analysis , Calcinosis/etiology , Calcium/blood , Calcium/metabolism , Hypocalcemia/etiology , Kidney/analysis , Male , Osteoporosis/etiology , Phosphorus/metabolism , Rats , Rats, Inbred Strains , Restraint, PhysicalABSTRACT
Hypokinesia induces mineral changes, including changes in calcium and phosphorus metabolism, which involve their increased renal excretion, deposition in soft tissues, and development of osteoporosis. These experiments were designed in order to ascertain the role of active metabolites (hydroxy-cholecalciferol) and changes in phosphorus in the diet on calcium accumulation in bone, soft tissue, and renal calcinosis, and changes in calcium-phosphorus metabolism in rats during prolonged and severe hypokinesia.
