EFFECTS OF ALFACALCIDOL ON MUSCLE STRENGTH, MUSCLE FATIGUE, AND BONE MINERAL DENSITY IN AGED RATS

「Abstract」Several recent studies have demonstrated that vitamin D affects not only bone but also muscle to prevent falls and osteoporotic fractures. However, these effects on muscle and the mechanisms of fall-prevention are still unclear. In this study, we investigated the effects of alfacalcidol (1α(OH)D3) on muscle strength, muscle fatigue, and bone mineral density (BMD) in aged rats. Alfacalcidol (0.1μg/kg/day) or its vehicle was administered orally for 4 weeks in 8-month-old female Wistar rats. The maximum contraction tension of the calf muscles was measured as muscle strength, and muscle fatigue was evaluated as the percentage strength to the initial contraction strength. Muscle strength and fatigue were then normalized using the body weight. BMD at the distal third of the femur was measured. Alfacalcidol administration significantly increased the maximum muscle strength (increase of 5-7%, P