age-associated decline in the ca2+ pump function of cardiac sarcoplasmic reticulum ( sr ) , and increase in the ca2+ pump activity of sarcolemma ( sl ) were suggested by my previous study which compared the atp-energized in vitro ca2+ transport activities of these membranes from young ( 3-4-month-old ) and aged ( 24-25-month-old ) rat myocardium ( biochim . biophys . acta , 678 ( 1981 ) 442-459 ) .
C0018787
cardiac
C0027061
myocardium