CALCIUM-UPTAKE AND ATPASE ACTIVITY OF SARCOPLASMIC-RETICULUM VESICLESISOLATED FROM CONTROL AND SELENIUM-DEFICIENT LAMBS

The calcium uptake and ATPase activity were studied using fragmented s arcoplasmic reticulum (FSR) vesicles from normal and selenium (vitamin E) - deficient lambs. The latter group was suffering from white muscl e disease (WMD). The calcium uptake of FSR vesicles from muscle of WMD lambs was reduced 10-fold as compared to those from normal lambs. An inverse relationship was found with the calcium uptake ability of the FSR vesicles and the severity of WMD. ATPase activity was nonsignifica ntly lower in vesicles from WMD lambs. The most active FSR vesicles fr om both normal and WMD lambs banded at 27% when purified on linear suc rose density gradients. The number of protein bands appearing in acryl amide gels of the purified vesicles appeared to be directly proportion al to the severity of WMD. The Se-75 cosedimented with the calcium upt ake and ATPase activity when FSR vesicles from a lamb injected With Se -75-selenite were subjected to linear sucrose density gradient centrif ugation, suggesting that selenium is incorporated into these vesicles. Injection of selenium into WMD lambs resulted in significantly greate r calcium uptake activity in vesicles 18 and 38 days later as compared with untreated WMD lambs. Injection of selenium in WMD lambs resulted in a marked decrease in plasma CPK activity and a significant increas e of glutathione peroxidase activity in the blood.