Gregory H Turner, Weike Bao, Beat M Jucker, John J Lepore, Robert N Willette, and Kevin S Thorneloe
Transient receptor potential channel vanilloid 4 (TRPV4) is a non-selective Ca2+ permeable cation channel, recently implicated by computational methods as a key signalling component during myocardial infarction. We previously showed that pharmacological TRPV4 inhibition can prevent and resolve pulmonary edema in pre-clinical heart failure animal models. Here, we examined the impact of genetic deletion of TRPV4 (TRPV4-/-) on cardiac function, both basally and following myocardial infarction. Cardiac function was similar in wild type and TRPV4-/- mice under normal conditions. By contrast, following myocardial infarction induced by permanent ligation of the left anterior descending coronary artery, left ventricular systolic and diastolic volumes were reduced and ejection fraction was significantly improved in TRPV4-/- when compared to wild type mice. Consistent with the differences in chamber volumes between TRPV4-/- and wild type mice, myocardial infarction induced a significant increase in heart weight and left ventricular mass index in wild type, but not in TRPV4-/- mice. In a separate cohort of mice, we also investigated the effect of genetic deletion of TRPV4 on infarct size after a 30 min myocardial ischemia and 24 hours reperfusion. There were no differences in myocardial infarct size or area at risk in TRPV4-/- and wild type mice after ischemia/reperfusion injury. These results suggest that TRPV4 does not mediate acute myocardial ischemic injury, but does play an important role in ventricular remodelling known to correlate with poor outcomes following acute myocardial infarction.