title: Endothelial cells influence the sodium nitroprusside mediated inhibition of platelet aggregation by an as yet unkown pathway.
abstract: The clinical use of Sodium nitroprusside (SNP) may be associated with an alteration of platelet function. The main focus of this study was the effect of SNP on platelet aggregation in the absence or presence of endothelial cells.
  
  
  METHODS
  Platelets were incubated with different concentrations of SNP with and without endothelial cells. Platelet aggregation was induced by ADP.
  
  
  RESULTS
  Platelet aggregation was significantly inhibited by all concentrations of SNP. Endothelial cells significantly increased this inhibitory effect of SNP. Time course studies showed an inverse correlation of incubation time to platelet aggregation inhibition in the absence of endothelial cells, and a direct correlation in the presence of endothelial cells. Blocking platelet and endothelial cell guanylate cyclase with 1 H-(1,2,4)-oxadiazolo(4,3-a) quinoxalin-1-one (ODQ), or pretreatment of the endothelial cells with cyclooxygenase - inhibitors, had no influence on the increased inhibitory effect of the endothelial cells. Cyanide reversed the inhibitory effect of SNP completely.
  
  
  CONCLUSIONS
  Endothelial cells play an important role in the SNP mediated inhibition of platelet aggregation. The effect is reversible only by cyanide, not by blocking classical NO signal transduction.
authors.affiliation: Klinik für Kinder und Jugendliche, University of Erlangen-Nuremberg, Loschgestr 15, 91054, Erlangen, Germany. hans-georg.topf@uk-erlangen.de.
authors.forename: Hans-Georg
authors.initials: HG
authors.lastname: Topf
authors.forename: Manfred
authors.initials: M
authors.lastname: Rauh
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Rascher
authors.forename: Jörg
authors.initials: J
authors.lastname: Dötsch
authors.forename: Jens M
authors.initials: JM
authors.lastname: Klinge