Garay R, Braquet P
Biochem Pharmacol. 1986 Aug 15;35(16):2811-5. doi: 10.1016/0006-2952(86)90194-2.
We investigated the effects of PAF-acether and its specific antagonist BN 52021 on Na+ and K+ transport systems in human red cells and mouse macrophages. PAF-acether and BN 52021 exhibited specific and opposite effects on a Cs+-stimulated, K+ efflux in human red cells. PAF-acether increased and BN 52021 decreased the apparent dissociation constant for external Cs+ without significant effects on the maximal rate of K+ translocation. In mouse macrophages, PAF-acether stimulated a quinidine-sensitive K+ efflux. In the presence of the Ca2+-ionophore A 23187, PAF-acether and BN 52021 showed opposite effects (stimulation and inhibition respectively). For most cells, membrane potential is dependent on K+-permeability. In addition, opening of potential-dependent Ca2+ channels appears to be associated with cell activation in several models. We thus propose that the specific interaction of PAF-acether with a K+:K+ exchange increases Ca2+ uptake through transitory changes in membrane potential. This in turn may lead to a more permanent membrane hyperpolarization through to opening of Ca2+ dependent, K+ channels.
我们研究了血小板活化因子（PAF - 乙酰醚）及其特异性拮抗剂BN 52021对人红细胞和小鼠巨噬细胞中钠钾转运系统的影响。PAF - 乙酰醚和BN 52021对人红细胞中铯离子（Cs⁺）刺激的钾离子外流表现出特异性的相反作用。PAF - 乙酰醚增加而BN 52021降低细胞外Cs⁺的表观解离常数，而对钾离子转运的最大速率无显著影响。在小鼠巨噬细胞中，PAF - 乙酰醚刺激一种对奎尼丁敏感的钾离子外流。在钙离子载体A 23187存在的情况下，PAF - 乙酰醚和BN 52021表现出相反的作用（分别为刺激和抑制）。对于大多数细胞，膜电位取决于钾离子通透性。此外，在几种模型中，电压依赖性钙离子通道的开放似乎与细胞激活有关。因此我们提出，PAF - 乙酰醚与钾离子：钾离子交换的特异性相互作用通过膜电位的瞬时变化增加钙离子摄取。这反过来可能通过钙离子依赖性钾离子通道的开放导致更持久的膜超极化。
