Mechanisms of Interaction of a Plasmalogenic Analog of Platelet-Activating Factor with Human Platelets

V. I. Kulikov^* and G. I. Muzya

Research and Development Center for Medical Biotechnology, Ministry of Public Health of the Russian Federation, ul. Shchukinskaya 6, Moscow, 123182 Russia; fax: (095) 190-0100

^* To whom correspondence should be addressed.

Received July 3, 1998; Revision received December 22, 1998

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The interaction of a plasmalogenic analog of platelet-activating factor (1-O-alk-1´-enyl-2-acetyl-sn-glycero-3-phosphocholine; 1-alkenyl-PAF) with human platelets was studied. 1-Alkenyl-PAF induced an increase in intracellular Ca²⁺ concentration and inhibition of adenylate cyclase at significantly higher concentrations than PAF. 1-Alkenyl-PAF inhibits PAF-induced platelet aggregation but has no effect on ADP- or thrombin-induced aggregation of human platelets. In contrast to PAF, 1-alkenyl-PAF increases [³H]PGE₁ binding with human platelets. The properties of 1-alkenyl-PAF as an agonist or antagonist of PAF receptors apparently depend on its concentration in the cell medium. Under physiological conditions 1-alkenyl-PAF might be a natural PAF antagonist acting in the human cardiovascular system.

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KEY WORDS: platelet-activating factor, platelets, plasmalogenic PAF analog

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