THE EFFECT OF INVITRO AND INVIVO CELLULAR AGING ON THE ACTIVE CALCIUM-TRANSPORT IN HUMAN INSIDE-OUT RED-CELL MEMBRANE-VESICLES

Modelling of the in, vivo and in, vitro aging processes in the human red cell has stressed the following features of the active calcium uptake by inside-out vesicles: 1) it is higher in the outdated, in, vitro aged, than in the fresh red cell (p<0.0005), and in the densest, in, vivo aged fraction than in the lightest, young fraction (p=0.08); 2) it increases following stimulation by excess calmodulin to values that are not significantly different; 3) it decreases to the same value in the absence of endogenous calmodulin and inhibitor, with and without exogenous calmodulin; 4) it is the target of a non-competitive inhibition, that is stronger in the fresh than in the outdated red cell. We conclude that the aging process does not involve neither membrane Ca-ATPase nor calmodulin, but rather the interaction of the calcium pump with the inhibitor of Ca-ATPase.