Influence of Ouabain on Contractile Force, Resting Tension, Ca 45 Entry and Tissue Ca Content in Rat Atria

Abstract

As was the case with guinea pig atria, ouabain induced a small but significant increment in Ca⁴⁵ uptake and a drop of tissue Ca content in rat atria during the positive inotropic effect. In ouabain contractures, the uptake rate increased 87% to 170% and there was little increase in tissue Ca. Concentrations of the glycosides required to produce a positive inotropic effect and contracture in rat atria were 100- to 200-fold greater than those required in guinea pig atria.