[Ability of a lipopolysaccharide toxin to intensify the functional response of human thrombocytes to thrombin...

The preincubation of isolated washed human platelets with lipopolysaccharide toxin (LPS) from Salmonella typhimurium (10 min, 37 degrees) speeds up the thrombin-induced aggregation. Besides, LPS-pretreatment was shown to alter the turnover of polyphosphoinositides stimulated by thrombin and significantly elevated concentrations of diacylglycerol and thromboxane B2 in comparison with control platelets. However, LPS does not influence on the lipid fluidizing effect of thrombin action as testifies by ESR spectroscopy with doxyl-stearic acids as spin-probes. An LPS pretreatment of platelets that induces no aggregation by itself is proposed might transform cells into a state of hidden activation" associated with the accumulation of such products as diacylglycerol and precursors of thromboxane B2. Addition of thrombin to such "preactivated" platelets could cause a more effective aggregation.