ORIGINAL ARTICLES   

International Angiology 2002 June;21(2):134-7

Copyright © 2003 EDIZIONI MINERVA MEDICA

language: English

Role of cytoplasmic calcium in platelet aggregation

Ariyoshi H., Aono Y., Tsuji Y., Ueda A., Tokunaga M., Uchide K., Sakon M., Monden M.

Department of Surgery II, Osaka University Medical School, Osaka, Japan

Background. Although adher­ence and aggre­ga­tion of plate­lets on an ­active sur­face such as ­exposed sub­en­do­the­lial ­matrix or for­eign sur­fac­es is inte­gral to the occlu­sion of blood ves­sels, its mode of ­action is not fully under­stood.
Methods. The role of cyto­plas­mic ion­ized Ca2+ con­cen­tra­tion ([Ca2+]i) in plate­let acti­va­tion ­induced by con­tact with a glass sur­face under shear-­stress was stud­ied by employ­ing con­fo­cal laser scan­ning micros­co­py (CLSM) in con­junc­tion with a par­allel plate flow cham­ber. Changes in [Ca2+]i and mor­phol­o­gy of aggre­gat­ing plate­lets on glass sur­face was simul­ta­ne­ous­ly exam­ined.
Results. Under stat­ic con­di­tion, con­tact with glass ­caused plate­let adhe­sion to the sur­face, which was asso­ciat­ed with [Ca2+]i rise and mor­pho­log­i­cal ­change; how­ev­er, plate­lets did not devel­op a large aggre­ga­tion on the sur­face. Under lower shear-­stress, the num­ber of the sin­gle plate­lets ­adsorbed on the sur­face was less than that under stat­ic con­di­tion. Although shear-­stress ­increased the num­ber of sin­gle plate­lets ­involved and ­enhanced mor­pho­log­i­cal ­change in aggre­gat­ing plate­lets in a shear-­stress relat­ed man­ner, the peak [Ca2+]i value in indi­vid­u­al plate­lets were not ­increased.
Conclusions. These obser­va­tions may sug­gest the cru­cial roles of shear-­stress in plate­let aggre­gate for­ma­tion at the site of arte­ri­al sten­o­sis. Shear-­stress might enhanc­es plate­let aggre­gate ­growth not ­through the enhance­ment of [Ca2+]i rise.