Relationship between action potential duration of ventricular cells and heart rate in dog under natural breathing

Summary

The ECG and transmembrane action potentials of the ventricular cells of 12 mongrel dogs at various heart rates under pentobarbital anesthesia and spontaneous breathing were simultaneously recorded. After statistical analysis of the records of 139 units, quantitative relationship between action potential durations (APDs) and heart rate, between QT intervals and heart rate, and between APD₉₀ and QT interval were recognized and regression equations were worked out by linear regression. The regression coefficients indicated that the relationship between APD₉₀, APD₅₀, QT interval and heart rate and that between APD₉₀ and QT interval were highly significant. In order to eliminate the effect of heart rate on APDs and QT interval, the correction formulas for heart rate on APDs and QT interval were worked out. After correction, the effect of heart rate on APDs and QT interval could be eliminated. This paper presents a practical method for the study of the effect of different agents on the APDs of ventricular cells and QT interval under spontaneous breathing.