Effects of volatile anesthetics on ryanodine-treated ferret cardiac muscle

The volatile anesthetics halothane, isoflurane, and sevoflurane depress myo cardial contractility by decreasing transsarcolemmal Ca2+ influx, Ca2+ rele ase from the sarcoplasmic reticulum, Ca2+ sensitivity of the contractile pr oteins, and cross-bridge performance. The aim of this study is to assess an d compare the effects of halothane, isoflurane, and sevoflurane on contract ility in conditions in which sarcoplasmic reticulum Ca2+ release is abolish ed by pretreatment with ryanodine. Ferret right ventricular papillary muscl es were exposed to ryanodine at 10(-6) M and then to incremental concentrat ions of halothane, isoflurane, or sevoflurane. In the presence of ryanodine , each anesthetic decreased isometric and isotonic contractility in a rever sible, concentration-dependent manner with no differences between anestheti cs and with little or no effect on time variables. It is likely that differ ences between anesthetic effects on contraction amplitude in isometric and isotonic twitches reside in their effects on the sarcoplasmic reticulum.