ELECTROPHYSIOLOGIC AND VOLTAGE CLAMP ANALYSIS OF THE EFFECTS OF SOTALOL ON ISOLATED CARDIAC-MUSCLE AND PURKINJE-FIBERS

  • 1 January 1985
    • journal article
    • research article
    • Vol. 232  (3) , 817-825
Abstract
The effect of dl-, d- and l-sotalol on electrophysiologic characteristics of guinea pig papillary muscles, sheep and rabbit Purkinje fibers was studied. Standard electrophysiological and voltage clamp techniques were used. At concentrations between 10-6 and 10-4 M, the main effect of sotalol consisted of prolongation of the action potential duration. In voltage clamp experiments this effect correlated with a substantial reduction of the time-dependent K current activated during the plateau of the action potential and a small reduction of the background K current. At concentrations above 10-4 M, a secondary shortening of the action potential concomitant with a fall in maximal rate of depolarization was seen. In voltage clamp experiments this effect correlated with a decrease of a slowly inactivating Na current. In the absence of catecholamines d- and l-sotalol exerted identical effects on action potentials and voltage clamp currents.