Protection against myocardial ischaemia/reperfusion injury by PPAR–α activation is related to production of nitric oxide and endothelin–1

Publisher Website
Google Scholar
Abstract
Background Ligands of peroxisome proliferator–activated receptor alpha (PPAR–α) have been shown to reduce ischaemia/reperfusion injury. The mechanisms behind this effect are not well known. We hypothesized that activation of PPAR–α exerts cardioprotection via a mechanism related to nitric oxide (NO) and endothelin–1 (ET–1). Methods Five groups of anaesthetized open–chest Sprague–Dawley rats were given the PPAR–α agonist WY 14643 1 mg/kg (WY; n = 7), dimethyl sulfoxide (DMSO, vehicle for WY; n = 6), the combination of WY and the NO synthase inhibitor N–nitro–L–arginine (L–NNA, 2 mg/kg) (n = 7), L–NNA only (n = 8) or 0.9% sodium chloride (NaCl, vehicle for DMSO and L–NNA; n = 8) i.v. before a 30 min period of coronary artery occlusion followed by 2 h of reperfusion. Infarct size (IS), eNOS and iNOS protein and ET–1 mRNA expression were determined. Results There were no haemodynamic differences between the groups during the experiment. The IS was 78 ± 3% of the area at risk in the DMSO group and 77 ± 2% in the NaCl group (P = NS). WY reduced IS to 56 ± 3% (P < 0.001 vs. DMSO group). When WY was administered in combination with L–NNA the cardioprotective effect was abolished (IS 73 ± 3%, P < 0.01 vs. WY 14643). L–NNA did not affect IS per se (78 ± 2%, P = NS). The expression of eNOS but not iNOS protein in ischaemic myocardium from rats was increased in the group given WY (P < 0.05). ET–1 mRNA levels were lower in the ischaemic myocardium following WY administration. Conclusion The results suggest that the PPAR–α activation protects the rat myocardium against ischaemia/ reperfusion injury via a mechanism related to production of NO, and possibly ET–1.