Ca++ Uptake and ATPase of Human Sarcoplasmic Reticulum*

Abstract
The preparation of grana (fragments of sarcoplasmic reticulum) from human striated muscle is described. The Ca++ -Mg++ moderated ATPase and Ca uptake activities of human grana was studied and compared with human muscle mitochondria. The difference in Ca uptake activity in grana prepared from human fast (white) and slow (red) muscles is not so pronounced as in rabbit muscle.