Potassium changes in the heart during homeometric autoregulation and acetyl strophanthidin

The ability of the heart to alter its basic contractility consequent upon an increase in its dynamic and metabolic activity should be considered a hemodynamic phenomenon of prime importance in understanding the heart's intrinsic adaptation to change. The experiments recorded herein demonstrate that, accompanying such contractility changes, an ionic alteration occurs and that a net potassium ion loss is at least a biochemical symptom of the altered state of the myocardium when either heart rate or systolic intraventricular pressure is increased independently. The fact that the amount of this potassium ion loss approximates that which is seen with a dose of digitalis which increases contractility suggests that the observed loss of potassium ion during homeometric autoregulation may turn out to be related importantly to the observed hemodynamic phenomena.