Antagonism of the contractile effect of digitalis by EDTA in the normal human ventricle

Abstract

1. 1. The administration of deslanoside to normal subjects is associated with a highly significant shortening of the ejection time index. 2. 2. The reduction in serum ionizable calcium induced by the administration of Na 2 EDTA to digitalized subjects is attended by a prompt and consistent reversal of the digitalis-induced shortening of the ejection time index. 3. 3. The administration of Na 2 EDTA in undigitalized subjects evoked significantly less prolongation of the ejection time index than in digitalized individuals, although the changes in serum calcium were identical. 4. 4. It is postulated that a reduction in ionizable serum calcium antagonizes the contractile effects of deslanoside, as reflected by these alterations in the ejection time index.