Abstract 54: Probenecid Improves Myocardial Function in an Ischemic Heart Disease Murine Model
Introduction Probenecid, previously used for the treatment of gout, is a transient receptor potential vanilloid 2 (TRPV2) agonist. We have found TRPV2 in murine cardiomyocytes and when stimulated by probenecid, results in a positive inotropic response through Ca2+ influx independent of β-adrenergic signaling. Our hypothesis is that probenecid will increase contractility without affecting cell survival.
Methods We studied the role of probenecid as a positive inotrope in a mouse model of ischemic heart disease. We administered probenecid via intraperitoneal injections (100mg/kg) before and after ischemia/reperfusion injury (I/R) and orally via treated water (100mg/kg daily for 4 weeks), using saline injections and untreated water as respective controls. Ischemia was induced by a 45 minute ligation of the LAD followed by reperfusion and all mice were followed serially via echocardiography. We also evaluated the effects of probenecid on HL-1 cell apoptosis by conducting cell viability assays.
Results Treatment with probenecid before I/R had no effect on subsequent infarct size (51.6±3.71% vs. 53.4±1.54%;P=NS). However, post-I/R probenecid caused an increase in ejection fraction (EF) of 10.9±1.98% in mice with initial EF between 40-50% (n=6; P<0.01) and 7.28±1.63% in mice with higher initial EF (50-60%) (n=6; p<0.01). Echocardiographic analysis of mice with oral probenecid after I/R demonstrated higher EF and smaller diastolic volume (47.19±2.29%; 79.57mL±1.63; n=6) compared to untreated mice (43.67±2.91%; 89.05mL±5.67; n=6). Cell viability assays showed high concentrations of probenecid had minimal effect on cell viability (88.6±6.2% of control) whereas treatment with high concentrations of isoproterenol (10mM) greatly decreased cell viability (6.7±0.1% of control).
Conclusions These experiments demonstrate 1) probenecid increases myocardial contractility at baseline and significantly more so after I/R injury; 2) probenecid therapy improves function when used chronically; 3) the increase in contractility is not associated with either increased infarct size in vivo or apoptosis in vitro. Thus, unlike other positive inotropes, such as isoproterenol, probenecid increases contractility without resulting in significant cell death.
- © 2012 by American Heart Association, Inc.