Cardiac-specific knockout of ET_(A)receptor mitigates low ambient temperature-induced cardiac hypertrophy and contractile dysfunction

摘要

Cold exposure is associated with oxidative stress and cardiac dysfunction.The endothelin(ET)system,which plays a key role in myocardial homeostasis,may participate in cold exposure-induced cardiovascular dysfunction.This study was designed to examine the role of ET-1 in cold stress-induced cardiac geometric and contractile responses.Wild-type(WT)and ETA receptor knockout(ETAKO)mice were assigned to normal or cold exposure(48C)environment for 2 and 5 weeks prior to evaluation of cardiac geometry,contractile,and intracellular Ca21 properties.Levels of the temperature sensor transient receptor potential vanilloid(TRPV1),mitochondrial proteins for biogenesis and oxidative phosphorylation,including UCP2,HSP90,and PGC1a were evaluated.Cold stress triggered cardiac hypertrophy,depressed myocardial contractile capacity,including fractional shortening,peak shortening,and maximal velocity of shortening/relengthening,reduced intracellular Ca21 release,prolonged intracellular Ca21 decay and relengthening duration,generation of ROS and superoxide,as well as apoptosis,the effects of which were blunted by ETAKO.Western blotting revealed downregulated TRPV1 and PGC1a as well as upregulated UCP2 and activation of GSK3b,GATA4,and CREB in cold-stressed WT mouse hearts,which were obliterated by ETAKO.Levels of HSP90,an essential regulator for thermotolerance,were unchanged.The TRPV1 agonist SA13353 attenuated whereas TRPV1 antagonist capsazepine mimicked cold stress-or ET-1-induced cardiac anomalies.The GSK3b inhibitor SB216763 ablated cold stress-induced cardiac contractile(but not remodeling)changes and ET-1-induced TRPV1 downregulation.These data suggest that ETAKO protects against cold exposure-induced cardiac remodeling and dysfunction mediated through TRPV1 and mitochondrial function.