Increased Na+ concentration and altered Na/K pump activity in hypertrophied canine ventricular cells

Abstract

Hypertrophy in CAVB cells is associated with increased [Na+](subs). This results from an increase in Na+ influx, and a decreased sensitivity of I(p) for Na+ in the range of [Na+]i studied. There is no evidence for a decrease in total pump capacity or for a functional Na/K-ATPase isoform shift. The rise in Na+ contributes to the contractile adaptation and preservation of sarcoplasmic reticulum Ca2+ content at the low heart rates of the dog with CAVB.