BACKGROUND:Transient receptor potential vanilloid 4 (TRPV4), a calcium (Ca2+) permeable channel, is upregulated during myocardial ischemia-reperfusion (IR). Although TRPV4 inhibition has cardioprotective effects, its impact on arrhythmogenesis remains unclear.
OBJECTIVE:This study aimed to evaluate the antiarrhythmic effects of TRPV4 inhibition, using the TRPV4 antagonist GSK2193874 (GSK219) and TRPV4 knockout (TRPV4-/-) mice, after IR.
METHODS:Surface electrocardiogram and optical mapping recordings were performed during 15 minutes of global ischemia and 10 minutes of reperfusion in Langendorff perfused mouse hearts. Ca2+ sparks were detected by confocal microscopy, and protein expression was analyzed by Western blot.
RESULTS:GSK219 or TRPV4 deletion significantly decreased the incidence and duration of ventricular tachycardia during reperfusion. TRPV4 inhibition shortened Ca2+ transient (CaT) recovery, suppressed CaT alternans, and decreased Ca2+ leak without affecting IR-induced prolongation of action potential duration (APD) and APD alternations. Activation of TRPV4 by GSK101790A (GSK101) increased arrhythmia susceptibility and Ca2+ leak. Moreover, GSK101 prolonged CaT recovery and promoted CaT alternans, which were greatly avoided by pretreatment with Ca2+/calmodulin-dependent protein kinase II (CaMKII) inhibitor. Interestingly, IR or GSK101 markedly increased the phosphorylation of CaMKII, ryanodine receptors, and phospholamban, which was significantly blocked by TRPV4 inhibition.
CONCLUSION:TRPV4 inhibition exerts antiarrhythmic effects after IR by modulating CaMKII-dependent Ca2+ handling abnormalities, reducing CaT alternans and Ca2+ leak, without affecting APD.