An α‐Tubulin‐Dependent Mechanism for Isoflurane‐Mediated Cardioprotection

Abstract

Volatile anesthetics such as isoflurane (ISO) protect the myocardium from ischemia and reperfusion injury. Nitric oxide (NO) signaling has been identified as a critical component of anesthetic-mediated cardioprotection. As endothelial nitric oxide synthase (eNOS) can be regulated by ISO and the acetylation state of α-tubulin, we wished to elucidate the mechanism responsible for the cardioprotective effects of ISO. We used human coronary artery endothelial cells to investigate the effect of ISO on acetylated α-tubulin expression and the role acetylated α-tubulin plays in the compartmentalization of eNOS and caveolin-1 (Cav-1). After ISO exposure, expression of acetylated α-tubulin was increased with immunofluorescence (IF) labeling (657.52 ± 7.01 vs 576.08 ± 9.13 u) and Western blotting compared to control cells. IF labeling of phosphorylated (P-) eNOS was also increased after ISO treatment (658.8 ± 7.64 vs 567.2 ± 7.26 u). Additionally, ISO stimulated the translocation of eNOS and Cav-1 to caveolar fractions as assessed by sucrose gradient fractionation. ISO-treated cells increased NO production compared to control cells (565.0 ± 90.02 vs 316.9 ± 37.3 pmol/mg) as previously demonstrated. These data suggest that the cardioprotective effects of ISO work through a tubulin-dependent mechanism that increases trafficking of eNOS and Cav-1 to caveolar fractions, increasing P-eNOS and therefore NO production.