Methods: The effects of halothane, isoflurane, and sodium pentobarbital on four different ATPase activities were studied at 37 degrees C in two distinct plasma membrane preparations, human red blood cells and synaptosomal membranes from rat cerebellum.
Results: Inhibition patterns of the PMCA by halothane and isoflurane at anesthetic concentrations were very similar in red blood cells and synaptosomal membranes. The half-maximal inhibition (I50) occurred at 0.25-0.30 mM halothane and 0.30-0.32 mM isoflurane. The PMCA in both membranes was significantly more sensitive to the inhibitory action of volatile anesthetics (I50 = 0.75-1.15 minimum alveolar concentration) than were other ATPases, such as the Sodium sup +, Potassium sup + -ATPase (I50 [nearly equal] 3 minimum alveolar concentration) or Magnesium sup 2+ -ATPase (I50 greater or equal to 5 minimum alveolar concentration). In contrast, sodium pentobarbital inhibited the PMCA in both membranes only at [nearly equal] 100-200-fold above its anesthetic concentrations. The other ATPases were inhibited at similar pentobarbital concentrations (I50 = 11-22 mM). 相似文献