Enhancement of Thrombin-Induced Degradation of Phosphatidylcholine in Reserpinized Rabbit Platelets

Summary

When 1-¹⁴C-arachidonic acid-labeled, washed platelets from the reserpinized rabbits were exposed to thrombin, the decrease in radioactivity of phospholipids was significantly stimulated as compared with the control platelets. The increase in radioactivity of fatty acids and their oxygenated metabolites was also stimulated. TLC analysis revealed that the stimulation of the decrease in radioactivity of phospholipids was almost exclusively attributed to that of phosphatidylcholine (PC), and that thrombin induced a slight but significant increase in radioactivity of phosphatidyl ethanolamine (PE) in the reserpinized platelets. The results suggest that thrombin-induced degradation of PC is enhanced in the reserpinized platelets, and the overproduced fatty acids would be metabolized to the larger amount of oxygenated products which result in the activation of the platelets. Thrombin-induced mobilization of PC to PE in the reserpinized platelet phospholipids was also suggested.

Keywords

Platelet phospholipids - Reserpine - Thrombin

• References

• 1 Watanabe Y, Soda M, Kobayashi B. Enhanced malondialdehyde formation in reserpinized rabbit blood platelets. Thromb Res 1979; 16: 25-35
• 2 Placer ZA, Cushman LL, Johnson BC. Estimation of product of lipid peroxidation (malonyl dialdehyde) in biochemical systems. Anal Biochem 1966; 16: 359-364
• 3 McMillan RM, MacIntyre DE, Gordon JL. Simple, sensitive fluorimetric assay for malondialdehyde production by blood platelets. Thromb Res 1977; 11: 425-428
• 4 Smith JB, Ingerman CM, Silver MJ. Malondialdehyde formation as an indicator of prostaglandin production by human platelets. J Lab Clin Med 1976; 88: 167-172
• 5 MacFarlane DE, Gardner S, Lipson C, Mills DC. Malondialdehyde production by platelets during secondary aggregation. Thromb Haemostas 1977; 38: 1002-1009
• 6 Bills TK, Smith JB, Silver MJ. Metabolism of ¹⁴C-arachidonic acid by human platelets. Biochim Biophys Acta 1976; 424: 303-314
• 7 Bills TK, Smith JB, Silver MJ. Selective release of arachidonic add from the phospholipids of human platelets in response to thrombin. J Clin Invest 1977; 60: 1-6
• 8 Silver MJ, Bills TK, Smith JB. Platelets and prostaglandins: The key role of platelet phospholipase A₂ activity. In: De Gaetano G, Garattini S. (eds.) Platelets: A multidisriplinary approach. 213-225 Raven Press; -New York 1978
• 9 Layne E. Protein estimation with the Folin-Ciocalteu reagent. In: Colowick SP, Kaplan NO. (eds.) Methods in Enzymology, III. p 448-450 Academic Press; New York: 1957
• 10 Hamberg M, Svensson J, Wakabayashi T, Samuelsson B. Isolation and structure of two prostaglandin endoperoxides that cause platelet aggregation. Proc Natl Acad Sti USA 1974; 71: 345-349
• 11 Hamberg M, Samuelsson B. Prostaglandin endoperoxides. Novel transformation of arachidonic add in human platelets. Proc Natl Acad Sci USA 1974; 71: 3400-3404
• 12 Hamberg M, Svensson J. Samuelsson B. Prostaglandin endoperoxides. A new concept concerning the mode of action and release of prostaglandins. Proc Natl Acad Sci USA 1974; 71: 3824-3828
• 13 Hamberg M, Svensson J, Samuelsson B. Thromboxanes: A new group of biologically active compounds derived from prostaglandin endoperoxides. Proc Natl Acad Sci USA 1975; 72: 2994-2998
• 14 Smith JB, Silver MJ. Prostaglandin synthesis by platelets and its biological significance. In: Gordon JL. (ed.) Platelets in biology and pathology. p 331-352 Elsevier/North-Holland Biomedical Press; Amsterdam: 1976
• 15 Rittenhouse-Simmons S, Deykin D. The activation by Ca2+ of platelet phospholipase A₂ . Effects of dibutyryl cyclic adenosine monophos-phate and 8-(N,N-diethylamino)-octyl-3,4,5-trimethoxybenzoate. Biochim Biophys Acta 1978; 543: 409-422
• 16 Rittenhouse-Simmons S, Russell FA, Deykin D. Transfer of arachidonic add to human platelet plasmalogen in response to thrombin. Biochem Biophys Res Commun 1976; 70: 295-301
• 17 Kannagi R, Koizumi K, Hata-Tanoue S, Masuda T. Mobilization of arachidonic add from phosphatidylethanolamine fraction to phos-phatidylcholine fraction in platelets. Biochem Biophys Res Commun 1980; 96: 711-718
• 18 Shattil SJ, McDonough M, Burch JW. Inhibition of platelet phospholipid methylation during platelet secretion. Blood 1981; 57: 537-544