Conclusion
Kcnh2 plays a protection role in sepsis-induced cardiac dysfunction (SCID) via regulating FAK/AKT-FOXO3A to block LPS-induced myocardium apoptosis, indicating a potential effect of the potassium channels in pathophysiology of SCID.
Methods
The caecal ligation puncture (CLP) surgery or lipopolysaccharide (LPS) injection was performed to induce septic cardiac dysfunction. Western blotting was used to determine KCNH2 expression. Cardiac function was examined by echocardiography 6 hours after CLP and LPS injection in Kcnh2 knockout (Kcnh2+/- ) and NS1643 injection rats (n ≥ 6/group). Survival was monitored following CLP-induced sepsis (n ≥ 8/group).
Results
Sepsis could downregulate KCNH2 level in the rat heart, as well as in LPS-stimulated cardiomyocytes but not cardiac fibroblast. Defect of Kcnh2 (Kcnh2+/- ) significantly aggravated septic cardiac dysfunction, exacerbated tissue damage and increased apoptosis under LPS challenge. Fractional shortening and ejection fraction values were significantly decreased in Kcnh2+/- group than Kcnh2+/+ group. Survival outcome in Kcnh2+/- septic rats was markedly deteriorated, compared with Kcnh2+/+ rats. Activated Kcnh2 with NS1643, however, resulted in opposite effects. Lack of Kcnh2 caused inhibition of FAK/AKT signalling, reflecting in an upregulation for FOXO3A and its downstream targets, which eventually induced cardiomyocyte apoptosis and heart tissue damage. Either activation of AKT by activator or knockdown of FOXO3A with si-RNA remarkably attenuated the pathological manifestations that Kcnh2 defect mediated.