title: Platelets-induced stimulation of endothelin-1 production and inhibition by phosphoramidon.
abstract: The effects of platelets on endothelin-1 (ET-1) production were examined by using cultured bovine pulmonary artery endothelial cells (ECs). Platelets (6 x 10(6) to 2 x 10(9) platelets/ml) prepared from rat peripheral arterial blood markedly stimulated immunoreactive (IR)-ET release from ECs into the culture medium, in a time-and platelet number-dependent manner. High-performance liquid chromatography analysis of the culture supernatant following exposure to platelets revealed one major IR-ET component corresponding to the elution position of synthetic ET-1. Northern blot analysis showed that platelets enhanced prepro ET-1 mRNA expression in the ECs. Increased IR-ET release was observed with the supernatant obtained after incubation of platelets, and this increment was significantly inhibited by transforming growth factor-beta 1 neutralizing antibody. Phosphoramidon, an ET converting enzyme inhibitor, significantly decreased the amount of IR-ET accumulating in the culture medium of ECs, incubated with or without platelets, and the decreasing effect of phosphoramidon in the presence of platelets was greater than that in their absence. A similar effectiveness of phosphoramidon was seen when transforming growth factor-beta 1 was used instead of platelets. Thus, platelets appear to stimulate the endothelial production of ET-1 in vitro, probably through a release of transforming growth factor-beta 1. We also suggest that the inhibition of ET converting enzyme by phosphoramidon is more effective in the augmented condition of ET-1 production than in the basal condition.
authors.affiliation: Department of Pharmacology, Osaka University of Pharmaceutical Sciences, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Umekawa
authors.forename: Y
authors.initials: Y
authors.lastname: Matsumura
authors.forename: N
authors.initials: N
authors.lastname: Yoshimura
authors.forename: S
authors.initials: S
authors.lastname: Murata
authors.forename: K
authors.initials: K
authors.lastname: Takada
authors.forename: Y
authors.initials: Y
authors.lastname: Tsukahara
authors.forename: M
authors.initials: M
authors.lastname: Takaoka
authors.forename: S
authors.initials: S
authors.lastname: Morimoto
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000502:physiology*; D002417:Cattle; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D003470:Culture Media; D019332:Endothelin-1; D016232:Endothelins / Q000096:biosynthesis* / Q000235:genetics; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism*; D006020:Glycopeptides / Q000494:pharmacology*; D009500:Neutralization Tests; D011498:Protein Precursors / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D016212:Transforming Growth Factor beta / Q000502:physiology*
chemical_list: D003470:Culture Media; D019332:Endothelin-1; D016232:Endothelins; D006020:Glycopeptides; D011498:Protein Precursors; D016212:Transforming Growth Factor beta; C008890:phosphoramidon