This study was undertaken to determine the effect of hypoxia on the cable properties of the canine ventricular muscle, employing a single sucrose gap method. Hypoxia caused the internal longitudinal resistance, Ri, to increase by 25% (P<0.02) and the length constant, λ, to decrease by 13% (P<0.05), significantly. The control values of Ri and λ were 198 ± 76 Ω cm and 0.81 ± 0.15 mm (mean ± SD, n=5), respectively. The membrane resistance, Rm, (control; 3026 ± 581 Ω ㎠) decreased by 6%. The membrane capacitance and the time constant were not affected significantly.
It was also examined whether the increase in Ri during hypoxia could be caused by hyperkalemia or acidosis, which are known to occur during hypoxia. The results showed that Ri was unchanged under acidosis (pH 6.1) or high K+ concentration (10.8 mM), thus suggesting the direct effect of hypoxia on Ri.
These results suggest that the changes in the cable properties play important roles in the genesis of arrhythmias during hypoxia.