THROMBIN INDUCES S-D-LACTOYLGLUTATHIONE ACCUMULATION BY ENHANCING PLATELET GLYCOLYTIC PATHWAY

1. Thrombin addition to human platelets stimulates L(+)lactate formati on and S-D-lactoylglutathione (SDL) accumulation. 2. Monoiodoacetamide decreases lactate formation and potentiates SDL accumulation through a significant increase of dihydroxyacetone phosphate and fructose1,6bi sphosphate intracellular levels both in resting and in activated plate lets. 3. A similar effect is produced by exogenous methylglyoxal on L( +)lactate formation and SDL accumulation. 4. Resting platelets complet ely transform (1 hr at 37 degrees C) the ketoaldehyde into D(-)lactate : 5. When platelets are incubated in the presence of thrombin only 60% of the ketoaldehyde is found as D(-)lactate and the accumulated S-D-l actoylglutathione represents about the 0.7% of the initial substrate. 6. During platelet stimulation with thrombin the hemithioacetal adduct , formed as a by-product of glycolytic pathway, can be rapidly removed for important steps of cellular activation.