tailieunhanh - Báo cáo khoa học: "Mechanism of UV light-induced photorelaxation in isolated rat aorta"

Tuyển tập các báo cáo nghiên cứu khoa học quốc tế về bệnh thú y đề tài: Mechanism of UV light-induced photorelaxation in isolated rat aorta | J. Vet. Sci. 2000 1 2 81-86 OURNAL OF Veterinary Science Mechanism of UV light-induced photorelaxation in isolated rat aorta Joo-heon Kim Yonggeun Hong1 and Cheol-soo Shim College of Veterinary Medicine and Institute of Animal Medicine Department of Biochemistry Gyeongsang National University Jinju 660-701 Korea. Isolated rat thoracic aorta which is pharmacologically precontracted by phenylephrine induces photorelaxation when exposed to long wave length UV-light. The aim of the present study was to characterize the mechanism of UV-light induced by photorelaxation in the rat aorta. 1. UV light relaxed both endothelium-intact and -denuded rat aortic rings contracted by phenylephrine. The magnitude of relaxation on UV light was dependent on the exposure time and slightly greatly in endothelium-denuded rings than in endothelium-intact preparations. 2. L-NAME 10 nM-100 uM but not D-NAME completely inhibited the photorelaxation in a concentration dependent manner. 3. The UV-induced relaxation was inhibited by methylene blue 1-100 uM and verapamil 100 nM and removal of extracellular Ca2 . In contrast UV-light induced photorelaxation was potentiated by Nw-nitro-L-arginine L-NOARG treatment. 4. In immunocytochemical analysis of UV-light induced iNOS and eNOS expression in rat aortas at which expression levels were increased in a time-dependent manner on UV-irradiation in aortic endothelium and smooth muscle respectively. These results suggest that UV light-induced photorelaxation may be due to nitric oxide from exogenously administered L-arginine as well as endogenous nitric oxide donors such as amino acid and arginine derivatives. Additional suggestion is that UV light stimulates the expression of nitric oxide synthases and its activity for nitric oxide generation is dependent on cytosolic Ca2 originated from extracellular space. Key words Photorelaxation endothelium EDRF rat aortic artery nitric oxide synthase nitric oxide Introduction In 1980 Robert Furchgott .

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