Figure 6. Relative changes in action potential duration at 95% repolarization (APD95) by verapamil at various external [K sup +]([K sup +]o) during cooling (control [C] values are normalized to the values obtained at 37 degrees Celsius and at 3.9 mM [K sup +]o). *P < 0.05 V (verapamil) versus C (control) at respective temperature.