title: Endothelium and the effect of activated neutrophils on arterial smooth muscle.
abstract: The aim of the study was to analyze the involvement of the endothelium in the effects of neutrophils (PMNL) on phenylephrine-precontracted isolated rings of the rat thoracic aorta and to compare their effects with those of peroxynitrite (ONOO(-)) and hypochlorous acid (HOCl). Activated PMNL-induced contraction of the precontracted aorta was prevented by the blockade of NO-synthase and by endothelium removal. In the endothelium-free preparations, the effect of PMNL reappeared in the presence of sodium nitroprusside. The effect of ONOO(-) and HOCl significantly differed from that of activated PMNL both in the presence and absence of the endothelium. It is therefore likely that neither ONOO(-) nor HOCl generated by transformation of superoxide anion radical (O2 (•-)) produced by PMNL is involved in their action. Reduction of the relaxant effect of nitric oxide derived from the endothelium by O2 (•-) seems to be the keystone mechanism in generation of PMNL-induced contraction.
authors.affiliation: Institute of Experimental Pharmacology and Toxicology, Slovak Academy of Sciences, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic.
authors.forename: Viktor
authors.initials: V
authors.lastname: Bauer
authors.affiliation: Institute of Experimental Pharmacology and Toxicology, Slovak Academy of Sciences, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic.
authors.forename: Ruzena
authors.initials: R
authors.lastname: Sotnikova
keywords: activated neutrophils; endothelium; hypochlorous acid; nitric oxide; peroxynitrite; rat thoracic aorta