Heat Shock Treatment Prior to Myocardial Infarction Results in Reduced Ventricular Remodeling

Abstract

Background: Heat shock (HS) treatment has been suggested to confer myocardial protection following ischemia. However, the effects of HS on left ventricular (LV) remodeling weeks after infarction have yet to be described. Methods: Myocardial infarction (MI) was created by coronary ligation in Lewis rats. Two experimental groups of animals were created: HS+MI group (n = 13) and MI group (n = 13). HS treatment consisted of an elevation in core temperature to 42°C for 15 min, 24 hr prior to MI. LV remodeling was assessed by transthoracic echocardiography (day 0, 1, 7, and 28) and by morphometric histology (day 28). Results: There was no significant difference in infarct size (TTC stain 24 hr) between HS+MI and MI groups. Using transthoracic echo there was a significant preservation of LV ejection fraction and fractional shortening in the HS+MI group as compared to MI group (7 and 28 days). Similar trends were seen by histology at 28 days but failed to reach significance. HSP27 expression by myocardial cells was shown to remain up-regulated (at 28 days) in both groups at the edges of the infarct area as compared to control myocardium. Conclusions: Our findings suggest that HS treatment prior to MI can result in a significant decrease in LV remodeling independent of a reduction in infarct size.

Keywords:

• Myocardium
• infarction
• heat shock
• remodeling