Effects of sevoflurane on contractile responses and electrophysiologic properties in canine single cardiac myocytes.

Abstract

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. 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. 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 (ICa) but did not show the use-dependent block. On the other hand, sevoflurane slightly reduced the Na+ currents (INa) only at a high concentration (4.0%). Intracellular cAMP concentration was reduced only at 4.0% sevoflurane. The negative inotropic effect of sevoflurane is mediated via the inhibition of ICa in canine ventricular myocyte but not associated with reduced intracellular cAMP except at a high dose (4.0%).