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Published on: May 4, 2015
Ischemic preconditioning maintains cardioprotection in aging normotensive and spontaneously hypertensive rats
Wangde Dai1, Boris Z Simkhovich, Robert A Kloner
1The Heart Institute, Good Samaritan Hospital, Los Angeles, California 90017, USA.
Insights
Ischemic preconditioning significantly reduces heart attack size in aging rats. This cardioprotective effect was observed in both normotensive Wistar-Kyoto rats and hypertensive rats, preserving cardiac function in the latter.
Area of Science:
- Cardiovascular Science
- Physiology
Background:
- Aging hearts are susceptible to ischemic damage.
- Ischemic preconditioning is a phenomenon where brief periods of ischemia protect against subsequent longer ischemic events.
Purpose of the Study:
- To investigate the efficacy of ischemic preconditioning in reducing infarct size and improving cardiac function in aging Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR).
Main Methods:
- Aging WKY and SHR rats underwent a 1-hour left anterior descending coronary artery occlusion followed by 3-hour reperfusion.
- Hearts were either preconditioned (3 cycles of 3 min occlusion/5 min reperfusion) or served as controls before the main occlusion.
- Infarct size and left ventricular (LV) function were assessed.
Main Results:
- Preconditioning significantly reduced infarct size in both WKY rats (24% vs. 51%) and SHR rats (13% vs. 62%) compared to controls.
- The risk zone was also reduced by preconditioning in SHR rats (41% vs. 51%).
- Preconditioning improved LV function during ischemia and reperfusion in SHR rats, but not in WKY rats.
Conclusions:
- Ischemic preconditioning provides robust cardioprotection against myocardial infarction in aging normotensive and hypertensive hearts.
- The protective benefits extend to preserving cardiac function, particularly in aging hypertensive hearts.
Abstract:
We determined whether ischemic preconditioning could reduce infarct size and improve cardiac function in both aging normotensive Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR). The left anterior descending coronary artery was occluded for 1h followed by 3 h reperfusion in aging ( approximately 16 months old) SHR rats and age-matched WKY rats. Hearts were either preconditioned or not (control group) prior to 1h of coronary artery occlusion. The preconditioning regimen consisted of three cycles of 3 min occlusion followed by 5 min reperfusion applied prior to the subsequent 1h occlusion. In WKY (n=12 each group), the risk zone was similar in the control (51+/-2%) and preconditioned group (46+/-2%; p=0.1). Preconditioning significantly reduced infarct size (as a percentage of the ischemic risk zone) (24+/-6%) compared to controls (51+/-5%; p=0.0026). In SHR rats (n=9 each group), the risk zone was smaller in the preconditioning group (41+/-3%) than in the control group (51+/-3%; p=0.035). Infarct size (as % of ischemic risk zone) was also significantly reduced in the preconditioned group (13+/-4%) compared to controls (62+/-5%; p<0.0001). For both WKY and SHR rats, for any sized risk zone the infarct size was smaller in preconditioned hearts compared with the control hearts. Preconditioning improved aspects of LV function during ischemia and reperfusion phase in SHR rats, but these benefits were not observed in the WKY rats. Preconditioning maintains powerful cardioprotection in aging normotensive hearts as well as aging hypertrophied hearts.
