Distribution of a persistent sodium current across the ventricular wall inguinea pigs

A tetrodotoxin-sensitive persistent sodium current, I-pNa, was found in gui nea pig ventricular myocytes by whole-cell patch clamping: This current was characterized in cells derived from the basal left ventricular subendocard ium, midmyocardium, and subepicardium. Midmyocardial cells show a statistic ally significant (P<0.05) smaller I-pNa than subendocardial and subepicardi al myocytes. There was no significant difference in I-pNa current density b etween subepicardial and subendocardial cells. Computer modeling studies su pport a role of this current in the dispersion of action potential duration across the ventricular wall.