Association of pulmonary artery photorelaxation with H2O2 metabolism by catalase.

Publication/Presentation Date

10-1-1991

Abstract

We have examined the mechanism governing guanosine 3',5'-cyclic monophosphate (cGMP)-associated photoinduced relaxation elicited by long-wavelength ultraviolet (UV) light of endothelium-removed, isolated bovine pulmonary arteries. Hypoxia, produced by gassing of the organ bath solution with 95% N2-5% CO2, inhibited photorelaxation. Photorelaxation was also inhibited by cyanide (1 mM NaCN) but was potentiated by lactate (5 mM). Irradiation of bovine pulmonary arterial smooth muscle with UV light (or exposure to exogenous H2O2) stimulated cyanide-inhibitable oxidation of methanol to formaldehyde, suggesting that UV light increased H2O2 metabolism via catalase. The UV light-induced oxidation of methanol by pulmonary arterial smooth muscle was also inhibited by hypoxia. Consumption of O2 was detected when pulmonary arterial tissue was exposed to UV light, but cyanide failed to interfere with this effect, consistent with the photochemical reduction of O2 within vascular smooth muscle in a manner independent of mitochondrial respiration. We propose that photorelaxation is associated with the intracellular photochemical reduction of O2 to form H2O2, which elicits increases of vascular smooth muscle cGMP levels via the catalase-dependent activation of soluble guanylate cyclase. In addition, we hypothesize that the photooxidation of NAD(P)H could contribute to the generation of H2O2, since the enhancement of photorelaxation by lactate may originate from increased levels of NADH.

Volume

261

Issue

4 Pt 2

First Page

1141

Last Page

1147

ISSN

0002-9513

Disciplines

Medicine and Health Sciences | Pediatrics

PubMedID

1928395

Department(s)

Department of Pediatrics

Document Type

Article

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