CARDIOVASCULAR EFFECTS OF SODIUM CAPRYLATE IN THE CAT

¹ Department of Physiology, School of Medicine, Stanford University

1. Sodium caprylate injected intravenously into cats in doses of 0.075 to 0.75 mM per kgm. causes an immediate temporary dilatation of the heart, increased stroke volume, cardiac output and venous pressure, and a decreased heart rate and arterial pressure.

2. The effects are qualitatively the same with varying doses and vary in a roughly quantitative way with the dose.

3. There is a small increase in stroke volume with caprylate over that shown when the diastolic volume is increased to an equal degree by injection of Ringers solution. Since the arterial pressure with caprylate is also greater than with Ringers solution, the work done by the heart per beat at constant diastolic volume is greater with caprylate than with Ringers solution. Accordingly, caprylate may be said to show a digitalis-like action on the cat heart.

4. Since there is no detectable increase in the diastolic distensibility of the ventricular muscle, nor any impairment of the force of systolic contraction, the dilatation of the heart is to be attributed to the increase in venous return.

5. It is suggested that sodium caprylate has a peripheral vasodilator action which masks its digitalis-like effect on the hearts This is one possible cause of the rise in venous pressure.