Effect of Hypokinesia on Calcium Loss in Calcium-supplemented and -unsupplemented Rats

Abstract

We undertook this study to determine total calcium (Ca(2+)) loss in Ca(2+)-deficient tissue and tissue Ca(2+) loss with and without Ca(2+) supplementation during hypokinesia (HK; diminished movement). Studies were conducted on 240 male Wistar rats during a pre-experimental period of 9 days and an experimental period of 98 days. Rats were equally divided into four groups: unsupplemented vivarium control rats (UVCR), unsupplemented hypokinetic rats (UHKR), supplemented vivarium control rats (SVCR), and supplemented hypokinetic rats (SHKR). Calcium supplementation of 2.6 mmol was given to animals in the SVCR and SHKR groups. Gastrocnemius muscle and right femur bone Ca(2+) level reduced (p <0.05) and plasma Ca(2+) level, and urine and fecal Ca(2+) loss increased (p <0.05) in the SHKR and UHKR groups compared to their pre-experimental values and the values in their respective vivarium control groups (SVCR and UVCR). Muscle and bone Ca(2+) content decreased more (p <0.05), while plasma Ca(2+) level, and urine and fecal Ca(2+) loss increased more (p <0.05) in the SHKR group than in the UHKR group. Tissue Ca(2+) deficiency during HK is more evident with than without Ca(2+) supplementation and Ca(2+) loss was exacerbated with higher than lower tissue Ca(2+) deficiency. This shows that tissue Ca(2+) deficiency does not result from the lower Ca(2+) content in the food consumed and the total bodily Ca(2+) loss is not caused by the higher tissue Ca(2+) content but due to the impossibility of the body to use Ca(2+) during prolonged HK.