Key result
Isoflurane facilitated the opening of the sarcolemmal K(ATP) channel in intact cells but not in excised, inside-out patches, suggesting an intracellular component is required.
Answers are grounded in this paper and cite their sources.
Isoflurane facilitates the opening of the cardiac sarcolemmal KATP channel via an intracellular mechanism, providing insight into anesthetic-induced cardioprotection.
BACKGROUND: Volatile anesthetics have cardioprotective effects that mimic ischemic preconditioning, including the involvement of adenosine triphosphate-sensitive potassium (K(ATP)) channels. However, evidence for a direct effect of volatile anesthetic on the K(ATP) channel is limited. In this study, the effects of isoflurane on the cardiac sarcolemmal K(ATP) channel were investigated. METHODS: Single ventricular myocytes were enzymatically isolated from guinea pig hearts. Whole cell and single-channel configurations, specifically the cell-attached and inside-out patch mode, of the patch clamp technique were used to monitor sarcolemmal K(ATP) channel current. RESULTS: In the cell-attached patch configuration, 2,4-dinitrophenol (150 microm) opened the sarcolemmal K(ATP) channel. Isoflurane (0.5 mm) further increased channel open probability and the number of active channels in the patch. In contrast, in the inside-out patch experiments, isoflurane had no significant effect on the K(ATP) channel activated by low ATP (0.2-0.5 mm). In addition, isoflurane had no effect on the K(ATP) channel when activated by adenosine diphosphate, adenosine + guanosine triphosphate, bimakalim, and 2,4-dinitrophenol under inside-out patch configurations. When K(ATP) current was monitored in the whole cell mode, isoflurane alone was unable to elicit channel opening. However, during sustained protein kinase C activation by 12,13-dibutyrate, isoflurane activated the K(ATP) current that was sensitive to glibenclamide. In contrast, isoflurane had no effect on the K(ATP) channel activated by 12,13-dibutyrate in a cell-free environment. CONCLUSIONS: Isoflurane facilitated the opening of the sarcolemmal K(ATP) channel in the intact cell, but not in an excised, inside-out patch. The isoflurane effect was not due to a direct interaction with the K(ATP) channel protein, but required an intracellular component, likely including the translocation of specific protein kinase C isoforms. This suggests that the sarcolemmal K(ATP) channel may have a significant role in anesthetic-induced preconditioning.
No takes yet. Share an insight, caveat, or question.
Fujimoto et al. (2002) studied this question. Isoflurane was evaluated on Sarcolemmal K(ATP) channel current and open probability. Isoflurane facilitated the opening of the sarcolemmal K(ATP) channel in intact cells but not in excised, inside-out patches, suggesting an intracellular component is required.
Synapse has enriched 10 related papers. Consider them for comparative context: