Prolongation of the action potential and reduction of the delayed outward K⁺ current by halothane in single frog atrial cells

Halothane has been shown to produce significant changes in heart rate and strength of contraction. We have studied the mechanism(s) of these effects by recording action potentials and transmembrane ionic currents in single cardiac cells from bullfrog atrium. Our results show (i) that the action potential was prolonged and its plateau was depressed; and (ii) that there was a significant inhibition of a potassium current, I_K, and a Ca²⁺ current, I_si, following halothane (2%) application.