al-Awadhi A M, Dunn C D
Department of Biological and Biomedical Sciences, Faculty of Applied Sciences, University of the West of England, Frenchay Campus, Coldharbour Lane, Bristol BS16 1QY, UK.
Br J Biomed Sci. 2000;57(4):273-80.
An association between consumption of fish or fish oils and a reduction in coronary heart disease was established in the 1980s. The mechanisms underpinning this effect have been investigated extensively, with the focus on a reduction in platelet adhesiveness and a lowering of plasma concentrations of low-density lipoprotein (LDL)-cholesterol. Possible effects on fibrinolysis have received less attention and produced conflicting data. The present study evaluates such effects under chemically restricted conditions in vitro, in a system that, based on studies with haemostatically active drugs of known mechanisms, appears to have some relevance to the in vivo situation. Eicosapentaenoic acid (EPA)--one of the major constituents of fish oil--produced a statistically significant (P < 0.05) enhancement of fibrinolysis, when added before formation of the fibrin clot, but generally had the reverse effect when added afterwards. Docosahexaenoic acid (DHA)--the other major constituent of fish oil--had a dramatic inhibitory effect on clot formation, when added prior to clot formation, and inhibited lysis when added after the clot was formed. Maxepa (Seven Seas Ltd.)--a concentrate of EPA and DHA, and the pharmaceutical equivalent of fish oils--did not influence fibrinolysis, when added prior to clot formation. When added after the clot had formed, however, it produced significant (P < 0.05) and dose-dependent effects that varied from enhancement to inhibition. Similarly, both high-density lipoprotein (HDL)- and LDL-cholesterol, when added after clot formation, produced significant (P < 0.05) concentration-dependent effects that varied from enhancement of fibrinolysis (at the lower concentrations tested) to inhibition at higher concentrations. Our findings suggest that the effects of fish oil and lipids are more complex than simple enhancement or inhibition of fibrinolysis. Rather, the benefits may depend both on their concentration and whether they are present before or after the fibrin clots are formed.
20世纪80年代确定了食用鱼类或鱼油与冠心病发病率降低之间的关联。人们对这种效应背后的机制进行了广泛研究，重点是血小板黏附性的降低以及血浆中低密度脂蛋白（LDL）胆固醇浓度的降低。对纤维蛋白溶解的可能影响受到的关注较少，且产生了相互矛盾的数据。本研究在体外化学限定条件下，在一个基于对已知机制的止血活性药物的研究而建立的系统中评估此类影响，该系统似乎与体内情况有一定相关性。二十碳五烯酸（EPA）——鱼油的主要成分之一——在纤维蛋白凝块形成前添加时，能使纤维蛋白溶解有统计学意义的增强（P<0.05），但在凝块形成后添加时通常会产生相反的效果。二十二碳六烯酸（DHA）——鱼油的另一种主要成分——在凝块形成前添加时对凝块形成有显著抑制作用，在凝块形成后添加时则抑制溶解。Maxepa（七海有限公司）——一种EPA和DHA的浓缩物，相当于药用鱼油——在凝块形成前添加时不影响纤维蛋白溶解。然而，在凝块形成后添加时，它会产生显著的（P<0.05）且剂量依赖性的影响，从增强到抑制不等。同样，高密度脂蛋白（HDL）胆固醇和LDL胆固醇在凝块形成后添加时，也会产生显著的（P<0.05）浓度依赖性影响，从较低测试浓度时的纤维蛋白溶解增强到较高浓度时的抑制。我们的研究结果表明，鱼油和脂质的影响比简单的纤维蛋白溶解增强或抑制更为复杂。相反，其益处可能既取决于它们的浓度，也取决于它们在纤维蛋白凝块形成之前还是之后存在。
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