[Effects of E. coli LPS on human platelet aggregation].
The effects of E. coli lipopolysaccharide (LPS) on washed platelets of the healthy volunteers were studied by measuring ADP induced aggregation and intracellular ionized calcium concentration ([Ca2+]i) by fluorescent calcium indicator, quin 2. Addition of LPS in platelets suspension in saline, caused an increased platelet aggregation. Adding LPS, however, in platelet suspension in Na(+)-citrated platelet poor plasma inhibited ADP aggregation. These trends were not affected by cyclooxygenase inhibitor, but partially antagonized by dibutyryl cyclic AMP, and verapamil. The intracellular calcium ion concentration ([Ca2+]i) was significantly increased (334 +/- 141 nM to 150 +/- 45 nM in control) on addition of LPS in platelet suspension containing ionized calcium. On the other hand, there was no significant difference observed with those suspended in calcium free solution (50 +/- 16 to 45 +/- 15 in control). These results indicate that changes of platelet aggregation by LPS were mediated by cyclic AMP and Ca2+, but not by arachidate derivatives. The author concludes that LPS changed the mechanism of Ca2+ influx of platelet membrane and elevated [Ca2+]i of platelets. These findings, however, probably are not the cause of aggregation of platelets during DIC.
Baba
K
K
Department of Anesthesia, Hokushin General Hospital, Nakano.
D000244:Adenosine Diphosphate / Q000494:pharmacology; D002118:Calcium / Q000097:blood; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000502:physiology; D004926:Escherichia coli; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology*; D010974:Platelet Aggregation / Q000187:drug effects
D008070:Lipopolysaccharides; D000244:Adenosine Diphosphate; D000242:Cyclic AMP; D002118:Calcium