EFFECTS OF EXOGENOUS PHOSPHOLIPIDS ON PLATELET ACTIVATION

Citation
Ls. Brunauer et Wh. Huestis, EFFECTS OF EXOGENOUS PHOSPHOLIPIDS ON PLATELET ACTIVATION, Biochimica et biophysica acta, 1152(1), 1993, pp. 109-118
Citations number
28
Categorie Soggetti
Biophysics,Biology
ISSN journal
00063002
Volume
1152
Issue
1
Year of publication
1993
Pages
109 - 118
Database
ISI
SICI code
0006-3002(1993)1152:1<109:EOEPOP>2.0.ZU;2-H
Abstract
Intercalation of amphipaths into the plasma membrane of platelets has a marked effect on their morphology. Incubation of platelets with phos phatidylcholines (PC) results in rounding of the platelet body and spi culation, while incubation with aminophospholipids such as dilauroylph osphatidylserine (DLPS) results in a biphasic shape change consistent with the bilayer couple model (Sheetz, M.P. and Singer, S.J. (1982) Pr oc. Natl. Acad. Sci. USA 71, 4457-4461) and with the activity of an am inophospholipid translocator facilitating transverse bilayer diffusion (Daleke, D.L. and Huestis, W.H. (1985) Biochemistry 24, 5406-5416). T he present study extends this work to investigate the effects of PC an d PS on platelet responses to a natural agonist, thrombin. PC incorpor ation produces a concentration-dependent progression of shape changes, beginning with surface ruffling and development of fine spicules, fol lowed by sphering of the cell body, and ending with the apparent loss of spicules. PC reduces platelet responses to thrombin only under cond itions that promote membrane vesiculation, seen morphologically as a l oss of spicules and biochemically as a loss of C-14-PC labeled membran e. PS homologues of varying acyl chain composition induce concentratio n- and time-dependent platelet sphering. Incorporation of PS inhibits thrombin-induced platelet shape change, granule secretion, and protein phosphorylation. Inhibition of these responses requires transit of th e exogenous PS to the cytofacial leaflet of the membrane bilayer.