Inhalational Anesthetic Effects on Na,K-ATPase in Rabbit and Rat Brains

Objectives: We studied the effects of inhalational anesthetics on Na,K-ATPase in brains, which relates to the maintenance of neuronal excitability, to reveal the mechanism of the effects of the anesthetics.
Methods: Na,K-ATPase was purified from the brains of rabbits and rats and ATPase activities were measured by the quantification of Pi (inorganic phosphate) production after ATP hydrolysis according to Chifflet’s method. We evaluated the effects of desflurane，sevoflurane, and isoflurane on ATPase activities.
Results: 1. We investigated the assay system to measure the Na,K-ATPase activities at 4 °C to study the effect of inhalational anesthetics with a low boiling point, particularly desflurane.
2. Desflurane，sevoflurane, and isoflurane inhibited Na,K-ATPase activities at 4 °C as well as at 37 °C. It was suggested that the degree of inhibition was the strongest with isoflurane.
3. The inhibition of Na,K-ATPase activities by inhalational anesthetics showed dose-dependency.
4. The affinities of Na,K-ATPase activity in rabbit and rat brains to sevoflurane and isoflurane were similar at 37 °C. On the other hand, the affinities of Na,K-ATPase activities in rabbit brains to sevoflurane and isoflurane were lower than those in rat brains at 4 °C. It is possible that the difference in lipid composition between rabbits and rats influences the cell membrane, including Na,K-ATPases.
Conclusions: Inhalational anesthetics, as well as many intravenous anesthetics, inhibit Na,K-ATPase activities, suggesting that the inhibition of Na,K-ATPase activities may be related to various effects of general anesthetics.