Overexpression of Heat Shock Protein 72 in Transgenic Mice Decreases Infarct Size In Vivo

Abstract

Background Previous studies have demonstrated that induction of heat shock protein (HSP) 72 by whole-body hyperthermia reduces infarct size in an in vivo model of ischemia and reperfusion. Furthermore, hearts obtained from transgenic mice that overexpress HSP72 demonstrate improved functional recovery and decreased infarct size in vitro after global ischemia and reperfusion. Methods and Results To test the hypothesis that overexpression of HSP72 in transgenic mice reduces infarct size in vivo, transgenic mice that were heterozygous for a rat HSP70i gene ([+]HSP72) and transgene-negative littermate controls ([−]HSP72) were subjected to 30 minutes of left coronary artery occlusion followed by 120 minutes of reperfusion. Core body temperature was monitored with a rectal thermometer and maintained between 36.5°C and 37.0°C with a heating pad. Infarct size, determined by dual staining with triphenyltetrazolium chloride and phthalocyanine blue dye, was smaller in [+]HSP72 mice compared with [−]HSP72 mice (12.7±2.8% [n=7] versus 33.4±4.5% [n=6], infarct size/risk area, respectively; P <.05; mean±SEM). Conclusions Overexpression of HSP72 reduces infarct size in this in vivo transgenic mouse model of myocardial ischemia and reperfusion.