PAR-2 activation at the time of reperfusion salvages myocardium via an ERK1/2 pathway in in vivo rat hearts.
Protease-activated receptor-2 (PAR-2) may have proinflammatory effects in some tissues and protective effects in other tissues. The role of PAR-2 in in vivo myocardial ischemia-reperfusion has not yet been determined. This study tested the hypothesis that PAR-2 activation with the PAR-2 agonist peptide SLIGRL (PAR-2 AP) reduces myocardial infarct size when given at reperfusion in vivo, and this cardioprotection involves the ERK1/2 pathway. Anesthetized rats were randomly assigned to the following groups with 30 min of regional ischemia and 3 h reperfusion: 1) control with saline; 2) vehicle (DMSO); 3) PAR-2 AP, 1 mg/kg given intravenously 5 min before reperfusion; 4) scrambled peptide (SP), 1 mg/kg; 5) the ERK1/2 inhibitor PD-98059 (PD), 0.3 mg/kg given 10 min before reperfusion; 6) the phosphatidylinositol 3-kinase inhibitor LY-294002 (LY), 0.3 mg/kg given 10 min before reperfusion; 7) PD + PAR-2 AP, 0.3 mg/kg PD given 5 min before PAR-2 AP; 8) LY + PAR-2 AP, 0.3 mg/kg LY given 5 min before PAR-2 AP; 9) chelerythrine (Chel) alone, 5 mg/kg given 10 min before reperfusion; and 10) Chel + PAR-2 AP, Chel was given 5 min before PAR-2 AP (10 min before reperfusion). Activation of ERK1/2, ERK5, Akt, and the downstream targets of ERK1/2 [P90 RSK and bcl-xl/bcl-2-associated death promoter (BAD)] was determined by Western blot analysis in separate experiments. PAR-2 AP significantly reduced infarct size compared with control (36 +/- 2% vs. 53 +/- 1%, P < 0.05), and SP had no effect on infarct size (53 +/- 3%). PAR-2 AP significantly increased phosphorylation of ERK1/2, p90RSK, and BAD but not Akt or ERK5. Accordingly, the infarct-size sparing effect of PAR-2 AP was abolished by PD (PAR-2 AP, 36 +/- 2% vs. PD + PAR-2 AP, 50 +/- 1%; P < 0.05) and by Chel (Chel + PAR-2 AP, 58 +/- 2%) but not by LY (PAR-2 AP, 36 +/- 2% vs. LY + PAR-2 AP, 38 +/- 3%; P > 0.05). Therefore, PAR-2 activation is cardioprotective in the in vivo rat heart ischemia-reperfusion model, and this protection involves the ERK1/2 pathway and PKC.
Jiang
Rong
R
Department of Cardiothoracic Surgery, Cardiothoracic Research Laboratory, Carlyle Fraser Heart Center of Crawford Long Hospital, Emory University School of Medicine, Atlanta, GA, USA.
Zatta
Amanda
A
Kin
Hajime
H
Wang
Ningping
N
Reeves
James G
JG
Mykytenko
James
J
Deneve
Jeremiah
J
Zhao
Zhi-Qing
ZQ
Guyton
Robert A
RA
Vinten-Johansen
Jakob
J
D000818:Animals; D004789:Enzyme Activation; D020935:MAP Kinase Signaling System; D008297:Male; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D015428:Myocardial Reperfusion Injury / Q000378:metabolism* / Q000473:pathology*; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D044464:Receptor, PAR-2 / Q000378:metabolism*
D044464:Receptor, PAR-2; D048052:Mitogen-Activated Protein Kinase 3