title: Autocrine/paracrine pattern of superoxide production through NAD(P)H oxidase in coronary arterial myocytes.
abstract: The present study tested the hypothesis that membrane-bound NAD(P)H oxidase in coronary arterial myocytes (CAMs) is capable of producing superoxide (O(2)(*-)) toward extracellular space to exert an autocrine- or paracrine-like action in these cells. Using a high-speed wavelength-switching fluorescent microscopic imaging technique, we simultaneously monitored the binding of dihydroethidium-oxidizing product to exogenous salmon testes DNA trapped outside CAMs and to nuclear DNA as indicators of extra- and intracellular O(2)(*-) production. It was found that a muscarinic agonist oxotremorine (OXO; 80 microM) increased O(2)(*-) levels more rapidly outside than inside CAMs. In the presence of superoxide dismutase (500 U/ml) plus catalase (400 U/ml) and NAD(P)H oxidase inhibitor diphenylene iodonium (50 microM) or apocynin (100 microM), these increases in extra- and intracellular O(2)(*-) levels were substantially abolished or attenuated. The O(2)(*-) increase outside CAMs was also confirmed by detecting oxidation of nitro blue tetrazolium and confocal microscopic localization of Matrigel-trapped OxyBURST H(2)HFF Green BSA staining around these cells. By electron spin resonance spectrometry, the extracellular accumulation of O(2)(*-) was demonstrated as a superoxide dismutase-sensitive component outside CAMs. Furthermore, RNA interference of NAD(P)H oxidase subunits Nox1 or p47 markedly blocked OXO-induced increases in both extra- and intracellular O(2)(*-) levels, whereas small inhibitory RNA of Nox4 only attenuated intracellular O(2)(*-) accumulation. These results suggest that Nox1 represents a major NAD(P)H oxidase isoform responsible for extracellular O(2)(*-) production. This rapid extracellular production of O(2)(*-) seems to be unique to OXO-induced M(1)-receptor activation, since ANG II-induced intra- and extracellular O(2)(*-) increases in parallel. It is concluded that the outward production of O(2)(*-) via NAD(P)H oxidase in CAMs may represent an important producing pattern for its autocrine or paracrine actions.
authors.affiliation: Dept. of Pharmacology and Toxicology, Medical College of Virginia, 410 North 12th St., Richmond, VA 23298, USA.
authors.forename: Guo
authors.initials: G
authors.lastname: Zhang
authors.forename: Fan
authors.initials: F
authors.lastname: Zhang
authors.forename: Rachel
authors.initials: R
authors.lastname: Muh
authors.forename: Fan
authors.initials: F
authors.lastname: Yi
authors.forename: Karel
authors.initials: K
authors.lastname: Chalupsky
authors.forename: Hua
authors.initials: H
authors.lastname: Cai
authors.forename: Pin-Lan
authors.initials: PL
authors.lastname: Li
mesh_terms: D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000166:cytology / Q000378:metabolism*; D066298:In Vitro Techniques; D032383:Myocytes, Cardiac / Q000378:metabolism*; D019255:NADPH Oxidases / Q000378:metabolism*; D010084:Oxidation-Reduction; D019899:Paracrine Communication / Q000502:physiology*; D013481:Superoxides / Q000378:metabolism*
chemical_list: D013481:Superoxides; D019255:NADPH Oxidases