in left atrial muscle preparations isolated from the guinea-pig heart and stimulated at 0.5 hz , binding of ouabain to glycoside binding sites on na , k-atpase was eliminated by lowering the extracellular na+ concentration from 145 to 27 mm , a condition reported to lower the intracellular na+ concentration by more than 60 % .
C0225860
left atrial
C0018787
heart