Calcium measurements in primates during and after hypokinesia in establishing calcium deficiency during prolonged hypokinesia

Hypokinesia (diminished movement) induces significant calcium (Ca) changes, but little is known about the effect of hypokinesia (HK) on Ca deficiency. Measuring Ca changes during and after HK the aim of this study was to dete rmine Ca deficiency during prolonged HK. Studies were done on 12 male Macaca mulatta (rhesus monkeys) aged 3-5 yr (5 .58-6.42 kg) during a 90-d pre-HK period, a 90-d HK period, and a 15-d post -HK period. Monkeys were equally divided into two groups: vivarium control monkeys (VCM) and hypokinetic monkeys (HKM). Hypokinetic monkeys were kept in small individual cages that restricted their movements in all directions without hindering food and water intakes. Urinary, fecal, and serum Ca, urinary and serum magnesium (Mg) and phosphat e (P), serum intact parathyroid hormone (iPTH), and calcitonin (CT) concent ration, body weight, food intake, fluid consumed and eliminated in urine we re measured. During the HK period, fecal Ca loss, urinary Ca, P, and Mg exc retion, fluid elimination, and serum P, Ca, and Mg concentration increased significantly (p less than or equal to 0.01), whereas serum iPTH and CT con centration, food and fluid intakes, and body weight decreased significantly (p less than or equal to 0.01) in the HKM group when compared with the VCM group. During the initial days of the post-HK period, serum Ca, Mg, and P concentration fecal Ca loss, urinary Ca, Mg, and P excretion, and fluid eli mination decreased significantly (p less than or equal to 0.01), whereas fl uid intake increased significantly (p less than or equal to 0.01) in the HK M group when compared with the VCM group. Food intake, body weight, and ser um iPTH and CT concentrations remained significantly (p less than or equal to 0.01) depressed in the HKP group when compared with the VCM; however, th ey increased as the duration of the post-HK period increased. By contrast, the corresponding parameters remained stable in the VCM group when compared with the baseline control values. It was shown that fecal and urinary Ca loss and serum Ca concentration incr eases significantly during HK, whereas during post-HK fecal, urinary, and s erum Ca decreases significantly. It was concluded that significant decrease of serum, urinary, and fecal Ca during post-HK may suggest the presence of Ca deficiency during prolonged HK.