EFFECTS OF SEVOFLURANE ON CONTRACTILE RESPONSES AND ELECTROPHYSIOLOGIC PROPERTIES IN CANINE SINGLE CARDIAC MYOCYTES

Background: The effects of sevoflurane was examined on the contractile response, membrane potential, membrane ionic currents, and intracellular cyclic adenosine monophosphate (cAMP) in canine single ventricular myocytes. Methods: Contraction was measured by a video-edge detector, and membrane ionic currents were recorded using whole-cell voltage clamp technique. Intracellular cAMP was measured with radioimmunoassay method. Results: Sevoflurane (1.0-4.0%) decreased the contraction of single ventricular cells in a dose-dependent and reversible manner. Also, sevoflurane decreased the action potential plateau and shortened the duration of action potential. Sevoflurane reduced the peak Ca2+ currents (I-Ca) but did not show the use-dependent block. On the other hand, sevoflurane slightly reduced the Na+ currents (I-Na) only at a high concentration (4.0%). Intracellular cAMP concentration was reduced only at 4.0% sevoflurane. Conclusions: The negative inotropic effect of sevoflurane is mediated via the inhibition of I-Ca in canine ventricular myocyte but not associated with reduced intracellular cAMP except at a high dose (4.0%).