Effect of Low Level Laser Irradiation Preconditioning On Infarct Size and Ventricular Remodeling in the Rat Heart

Abstract

Jitao Yang, Xianen Fa

Objectives: To investigate the effects of Low level laser irradiation (LLLI) preconditioning on the infarct size and ventricular remodeling in the rat heart.

Background: LLLI can reduce the inflammatory reaction, attenuate the infarct size and formation of scar tissue, promote cardiomyocyte proliferation in the rat heart after myocardial infarction (MI). The effects of LLLI preconditioning on myocardium in the infarcted rat heart were rarely reported. Greater understanding of LLLI’s underlying photobiomodulative mechnisms would be helpful in translating photobiomodulation (PBM) therapy into the clinic.

Methods: 3 days before establishing the model of rat MI, the LLLI was applied for the heart through the intercostal muscles in the chest in the LLLI group. The models of rat MI were induced by ligation of the left anterior descending coronary artery (LAD). At 4 weeks post MI, the hearts were harvested for histological analysis to determine the infarct size , the left ventricular wall thickness and the percentage of collagen fibers in the infarcted area.

Results: In laser preconditioning group, the infarct size reduced significantly (15±9% to 35±10%, p<0.05), the left ventricular wall thickness increased (0.64±0.0 2mm to 0.31±0.0 3mm, p<0.05) and the percentage of collagen fibers in the infarcted area attenuated (35.67±2. 40% to 64.34±2. 20%) than that in the control group.

Conclusion: LLLI preconditioning could markedly attenuate infact size formation, increase ventricular wall thickness and attenuate the formation of collagen fibers. LLLI has benefits on improving ventricular remodeling after MI. This found may have an important beneficial effect on preventing ischemic heart disease.

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