Effect of Endothelium-Derived Relaxing Factor in Platelet Adhesion under Flow Condition

• Main Authors: Chia Tai Chen, 陳佳黛
• Other Authors: C. J. Jen
• Format: Others
• Language: zh-TW
• Published: 1993
• Online Access: http://ndltd.ncl.edu.tw/handle/42179752479606073208

碩士 === 國立成功大學 === 生理學研究所 === 81 === Endothelium-derived relaxing factor (EDRF), a labile vasorelaxing agent, has been shown to influence the platelet function under static conditions. In this study, we used carbachol, acetylcholine (Ach), bradykinin to stimulate the endogenous EDRF release in S.D. rats animal model. One milliliter un-anticoagulated blood was drawn from the rat femoral artery and directly passed through a parallel-plate flow chamber. This system allowed us to examine the platelet adhesion to fibrinogen-coated surface under whole blood flow conditions. Our results demonstrated that 1). the administration of carbachol produced a transient and dose- related decrease in blood pressure and inhibited platelet adhesion under flow conditions. The cGMP and cAMP content in treated platelets were significantly higher than control. 2). the administration of hemoglobin increased platelet adhesion to fibrinogen-coated surface, presumably by blocking the transport of EDRF from endothelial cells to platelets. 3). Acetylcholine and bradykinin produced transient- decrease in blood pressure but did not significantly inhibit platelet adhesion. The cGMP and cAMP content in treated platelets also were not significantly different when compared with control. 4). L-NNA (N-nitro-L-arginine), an EDRF synthesis inhibitor blocking the L-arginine/nitric oxide pathway, caused elevated blood pressure in vivo and augmented platelet adhesion ex vivo. The cAMP content was significantly higher than control, but not cGMP. From the present study, endogenous EDRF not only modulates vascular tone but also influences platelet function under flow conditions.