Isoflurane depresses membrane currents associated with contraction in myocytes isolated from guinea-pig ventricle.
The influence of isoflurane on membrane currents, action potentials, and contraction was investigated in single cells isolated from guinea-pig ventricle. Isoflurane (1.65-4.45%) reduced the action potential duration at 20% and 90% repolarization times. When step depolarizations were applied under voltage-clamp conditions, there was a depression by isoflurane both of the second inward (calcium) current and of the contraction (measured by an optical method). Isoflurane also depressed "tail" currents, which were recorded on repolarization following a voltage-clamp step to 0 mV and which are thought to be activated by cytosolic calcium. Additional actions of isoflurane were investigated using a paired-pulse protocol. The observations were consistent with a reduction by isoflurane of calcium release. This action together with the reduction of calcium influx during the second inward current would contribute to the negative inotropic effect of isoflurane.
Terrar
D A
DA
Nuffield Department of Anaesthetics, Radcliffe Infirmary, Oxford, U.K.
Victory
J G
JG
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D003864:Depression, Chemical; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007530:Isoflurane / Q000493:pharmacokinetics / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects*; D009200:Myocardial Contraction / Q000187:drug effects*; D009206:Myocardium / Q000166:cytology
D007530:Isoflurane