Harris R H, Ramwell P W, Gilmer P J
Annu Rev Physiol. 1979;41:653-68. doi: 10.1146/annurev.ph.41.030179.003253.
The human platelet and erythrocyte differ quite dramatically in relation to the arachidonic acid cascade. The platelet synthesizes its own characteristic products, while the erythrocyte lacks cyclo-oxygenase activity but possesses other metabolic enzymes. In these and other cell types the metabolites are potentially determined by the cascade enzymes, the availability of cofactors, the presence of specific activators and inhibitors, and the selective binding or transport of intermediates. Endogenously synthesized metabolites may have intracellular actions or may be released and exert their effects extracellularly. Study of the cellular mechanisms mediating these effects, like study of the fast-acting hormones, has focused primarily on the cyclic nucleotides and calcium. Considering the diverse activities of several metabolites in the platelet however, these mechanisms seem to need reevaluation or refining. The released cascade metabolites may also act as intercellular signals over a short range. The range depends on their chemical stability in the absence of protective carriers and their selective uptake and metabolism by surrounding cells. Additionally, the effects will reflect the selective interaction of responsive cells with the spectrum of metabolites released. Answering these questions of complex intercellular interactions requires the identification and classification of characteristic responses and the metabolic profile of individual cell types in each tissue. Consequently, this type of analysis may best be done with isolated cells, such as the platelet and erythrocyte.
人类血小板和红细胞在花生四烯酸级联反应方面存在显著差异。血小板能合成其自身特有的产物，而红细胞缺乏环氧化酶活性，但拥有其他代谢酶。在这些以及其他细胞类型中，代谢产物可能由级联酶、辅因子的可用性、特定激活剂和抑制剂的存在，以及中间体的选择性结合或转运所决定。内源性合成的代谢产物可能具有细胞内作用，也可能被释放并在细胞外发挥作用。与对快速起效激素的研究一样，对介导这些效应的细胞机制的研究主要集中在环核苷酸和钙上。然而，考虑到血小板中几种代谢产物的多样活性，这些机制似乎需要重新评估或完善。释放的级联代谢产物也可能在短距离内作为细胞间信号起作用。其作用范围取决于它们在没有保护性载体时的化学稳定性以及周围细胞对它们的选择性摄取和代谢。此外，这些效应将反映反应性细胞与释放的代谢产物谱的选择性相互作用。要回答这些复杂的细胞间相互作用问题，需要识别和分类特征性反应以及每个组织中单个细胞类型的代谢谱。因此，这种类型的分析最好用分离的细胞来进行，比如血小板和红细胞。
