1. Archive
2. Vol.53, No.3

Flow-Mediated Release of Nitric Oxide from Lymphatic Endothelial Cells of Pressurized Canine Thoracic Duct

Abstract: We examined the effects of flow on lymphatic endothelial cells by using conventional cascade preparations of isolated coronary arteries without intact endothelium. The pressurized thoracic ducts were intraluminally perfused at a constant flow rate ranging from 0.5 to 2.0 ml/min. A linear relationship was observed between the flow rate and the normalized amount of relaxing substance(s) released from the lymphatic endothelial cells. Thus the flow rate of 2.0 ml/min produced ∼39% of sodium nitroprusside (SNP)–produced maximal relaxation in the cascade arterial rings. The acetylcholine (ACh, 10⁻⁵ M)- and flow-induced relaxations of the cascade arterial rings were completely reduced by the mechanical rubbing of lymphatic endothelial cells in the pressurized lymph vessels. Pretreatment with 5×10⁻⁵ M N^G-nitro-L-arginine methyl ester (L-NAME) on the lymphatic endothelial cells caused a significant reduction of the ACh- and flow-induced vasodilations of the cascade arterial rings. Pretreatment with 10⁻⁵ M indomethacin on the lymphatic endothelial cells produced no significant effect on the ACh- and flow-induced vasodilations. These findings suggest that lymphatic endothelial cells of canine thoracic ducts can produce and release endogenous nitric oxide by stimulation of flow (∼2.0 ml/min).

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