Figure 5.

Relationship between action potential duration and I_to density in rabbit left ventricular myocytes isolated from the subendocardial and subepicardial layers of the left ventricle. A. Action potential and I_to recordings at +60 mV in cells from the subendocardial and subepicardial layers of the left ventricle at 37 °C. The myocyte from the subendocardial layer was characterized by a long action potential duration and a moderate I_to density compared to the cell isolated from the subepicardial layer. B. A plot of the correlation between I_to density at +60 mV and action potential duration at 90 % repolarization (APD₉₀). There is a negative correlation between native I_to density and the APD₉₀ (y = −14.8x + 410, n = 18, r = −0.80, p < 0.05), i.e. the higher the I_to density the shorter the action potential duration.