Key Points
- To evaluate the electromechanical actions of racemic sotalol and its optical isomers (d-sotalol and l-sotalol) on isolated canine ventricular trabeculae and Purkinje strands.
- Applied dl-sotalol, d-sotalol, and l-sotalol across various concentrations to isolated canine ventricular trabecular muscles and Purkinje strand preparations.
- Assessed transmembrane electrical characteristics, action potential duration across multiple stimulation frequencies, and mechanical force development (pacing at 0.33 Hz to 2 Hz).
- dl-Sotalol and both optical isomers produced concentration-dependent increases in action potential duration without altering other transmembrane electrical characteristics, showing greater prolongation in Purkinje strands at slower stimulation frequencies.
- d-Sotalol was one to three times more potent than l-sotalol or dl-sotalol at producing a 50% maximal increase in Purkinje strand action potential duration.
- Each compound increased contractile force in ventricular trabeculae stimulated at 2 Hz, whereas force increases in Purkinje strands occurred only at slower rates (0.5 to 0.33 Hz).
Structured PICO
PPopulationIsolated canine ventricular trabecular muscle and Purkinje strand preparations
IInterventiondl-sotalol and its two optical isomers d- and l-sotalol
OOutcomeAction potential duration and transmembrane electrical characteristicssurrogate
Sotalol and its optical isomers increase action potential duration in canine cardiac tissues, suggesting its antiarrhythmic effects and risk of torsade de pointes are related to this mechanism rather than beta-blockade.