title: Peroxynitrite inhibits leukocyte-endothelial cell interactions and protects against ischemia-reperfusion injury in rats.
abstract: Peroxynitrite (ONOO-) anion, formed by the interaction of superoxide with nitric oxide (NO), has previously been implicated as a cytotoxic agent. However, the effects of this free radical species on neutrophil (PMN)-endothelial cell interactions is largely unknown. We investigated the direct actions of ONOO- on PMN adhesion to endothelial cells in vitro and in vivo, as well as the effects of ONOO- on PMN-mediated myocardial ischemia-reperfusion injury. In vitro, peroxynitrite (100-1,000 nM) inhibited the adhesion of rat PMNs to the endothelium of isolated thrombin- or H2O2-stimulated rat mesenteric artery (P < 0.01 vs. thrombin or H2O2 alone). In vivo, in the rat mesentery, thrombin (0.5 U/ml) or N(G)-nitro-L-arginine-methyl ester (50 microM) significantly increased venular leukocyte rolling and adherence, which were also significantly (P < 0.01) attenuated by ONOO (800 nM) accompanied by reduced P-selectin expression on the endothelial cell surface. Isolated perfused rat hearts were subjected to global ischemia and reperfusion with rat PMNs (10(8) cells), which resulted in profound cardiac depression (i.e., a marked reduction in left ventricular developed pressure and maximal rate of development of left ventricular pressure). Infusion of ONOO- reversed the myocardial contractile dysfunction of ischemic-reperfused rat hearts to near baseline levels, and markedly attenuated the accumulation of PMNs in the postischemic heart. The present study provides strong evidence that nanomolar concentrations of ONOO- both inhibit leukocyte-endothelial cell interactions and exert cytoprotective effects in myocardial ischemia-reperfusion injury. Furthermore, our results suggest that the inhibition of P-selectin expression by peroxynitrite is a key mechanism of the modulatory actions of ONOO- on leukocyte-endothelial cell interactions.
authors.affiliation: Department of Medicine, Cardiology Section, Tulane University School of Medicine, New Orleans, Louisiana 70112, USA. lefer1@jeflin.tju.edu
authors.forename: D J
authors.initials: DJ
authors.lastname: Lefer
authors.forename: R
authors.initials: R
authors.lastname: Scalia
authors.forename: B
authors.initials: B
authors.lastname: Campbell
authors.forename: T
authors.initials: T
authors.lastname: Nossuli
authors.forename: R
authors.initials: R
authors.lastname: Hayward
authors.forename: M
authors.initials: M
authors.lastname: Salamon
authors.forename: J
authors.initials: J
authors.lastname: Grayson
authors.forename: A M
authors.initials: AM
authors.lastname: Lefer
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic; D002448:Cell Adhesion / Q000187:drug effects; D002450:Cell Communication / Q000187:drug effects*; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects*; D007082:Ileum / Q000098:blood supply / Q000378:metabolism; D008297:Male; D017538:Mesenteric Artery, Superior; D018715:Microscopy, Video; D009126:Muscle Relaxation / Q000187:drug effects; D015428:Myocardial Reperfusion Injury / Q000201:enzymology / Q000503:physiopathology / Q000517:prevention & control*; D009504:Neutrophils / Q000187:drug effects*; D009566:Nitrates / Q000494:pharmacology*; D019007:P-Selectin / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D014699:Venules
chemical_list: D009566:Nitrates; D019007:P-Selectin; C039642:peroxynitric acid