Abstract 300: Topical Application of IcyHot Reduces Myocardial Infarct Size in Rodents by a TRPA1-dependent Mechanism
Toxic reactive aldehydes are formed during ischemia-reperfusion. The ion channel transient receptor potential ankryin 1 (TRPA1) is irreversibly modified by reactive aldehydes which can cause calcium influx and cell death. Here we tested whether topically applied creams containing a reversible TRPA1 agonist could reduce myocardial infarct size. Male Sprague-Dawley rats 8-10 weeks age were subjected to an in vivo myocardial ischemia-reperfusion model of 30 minutes of left anterior descending (LAD) coronary artery ischemia followed by 2 hours reperfusion. Prior to ischemia, rats were untreated or had 1g of cream applied to the abdomen. The creams tested were IcyHot, Bengay, Tiger Balm, or preparation H (Fig. 1A). Hearts were negatively stained for the area at risk and the infarct size was determined by using TTC staining (Fig. 1B). A subset of rodents prior to receiving IcyHot also received an intravenous bolus of the TRPA1 antagonist TCS-5861528 (1mg/kg) or AP-18 (1mg/kg). Interestingly, both IcyHot and Bengay reduced myocardial infarct size compared to untreated rodents (Fig. 1C and 1D IcyHot: 41±3%*, Bengay: 50±2%* versus control 62±1%, n=6/group, *P<0.001). Both preparation H and Tiger Balm failed to reduce myocardial infarct size (Tiger Balm: 63±2%, preparation H 59±2%). Giving a TRPA1 antagonist prior to IcyHot also blocked the reduction in infarct size. Our additional data also indicates the methyl salicylate (mint) in IcyHot and Bengay is the agent that limits myocardial infarct size. Since IcyHot and Bengay are safely used by humans, targeting TRPA1 by using products such as these could be quickly translatable and widely used to reduce ischemia-reperfusion injury.