EFFECTS OF EXOGENOUS GANGLIOSIDES ON INTRACELLULAR CA2-RESPONSES IN HUMAN PLATELETS( MOBILIZATION AND FUNCTIONAL)

Gangliosides, highly expressed in the outer leaflet of plasma membrane s, mediate a variety of biological processes, including cell-cell and cell-matrix interactions, We examined the effects of exogenous ganglio sides on intracellular Ca2+ mobilization and functional responses in h uman platelets. Gangliosides (GM(3) and GM(1)) inducted rapid and reve rsible elevation of intracellular Ca2+ in fura2-loaded platelets in a concentration-dependent manner. The Ca2+-mobilizing effect of ganglios ides was not mimicked by de-N-acetyl-GM(3), lactosylceramide, or free sialic acid, suggesting that structural integrity as ganglioside is es sential for this effect, GM(3) and GM(1) also induced platelet shape c hange by themselves and elicited aggregation in combination with epine phrine, Our observations suggest the involvement of ganglioside-activa ted platelets in atherosclerosis, in view of the high observed ganglio side levels in atherosclerotic lesions of human aorta.