Effect of temperature on action potential duration (APD90) of canine isolated epicardial (Epi), M cell, endocardial (Endo) tissue slices, and Purkinje fiber preparations under baseline conditions (control) and in the presence of E-4031 (1 μmol/L, IKr block) or chromanol 293B (293B, 30 μmol/L, IKs block) (n=8 for each). BCL = 2000 ms.
A: Superimposed action potentials recorded from the four ventricular cell types before and after an increase in ambient temperature of the superfusion solution from 36 to 39°C.
B: Summary data for the effect of hyperthermia on APD90 of Epi, M cell, Endo, and Purkinje preparations under conditions of prolonged repolarization.
Control and chromanol 293B APD data from Purkinje fibers at 40°C are lacking because of the effect of hyperthermia to accelerate spontaneous automaticity. * - p<0.05 and † - p<0.001 vs. control 36°C for each region, ‡ - p<0.05 and ∥- p<0.001 vs. 36°C for each condition. Mean ± SEM.