title: Acute reduction of lipoprotein(a) by tissue-type plasminogen activator.
abstract: BACKGROUND
  Lipoprotein(a) [Lp(a)] is a low density lipoprotein-like particle whose apolipoprotein B (apo B) moiety is disulfide-linked to apo(a), a plasminogen-like inhibitor of fibrinolysis in vitro. We hypothesized that plasma concentrations of Lp(a) are acutely affected by intravenous tissue-type plasminogen activator (t-PA).
  
  
  RESULTS
  Patients with unstable angina were randomized to receive either intravenous t-PA (n = 15) or placebo (n = 11). Two-way ANOVA using repeated measures revealed a significant effect of t-PA on concentrations of Lp(a) (p = 0.026). There was a 48% fall in Lp(a) from baseline concentrations in the t-PA group at 12 hours (p = 0.031) but not at 72 hours. Lp(a) in the placebo group was unchanged.
  
  
  CONCLUSIONS
  We conclude that t-PA produces a sharp and substantial but reversible reduction in plasma Lp(a). These data suggest that Lp(a) concentration is not as static in vivo as had been believed and might be acutely modifiable through some mechanism that induces its removal from the freely circulating state.
authors.affiliation: Division of Endocrinology and Metabolism, St. Michael's Hospital, University of Toronto, Ontario.
authors.forename: R A
authors.initials: RA
authors.lastname: Hegele
authors.forename: M R
authors.initials: MR
authors.lastname: Freeman
authors.forename: A
authors.initials: A
authors.lastname: Langer
authors.forename: P W
authors.initials: PW
authors.lastname: Connelly
authors.forename: P W
authors.initials: PW
authors.lastname: Armstrong
mesh_terms: D000789:Angina, Unstable / Q000097:blood / Q000188:drug therapy*; D001055:Apolipoproteins B / Q000097:blood; D005260:Female; D006801:Humans; D008055:Lipids / Q000097:blood; D017270:Lipoprotein(a); D008074:Lipoproteins / Q000097:blood* / Q000187:drug effects; D008297:Male; D008875:Middle Aged; D010958:Plasminogen / Q000037:antagonists & inhibitors; D013997:Time Factors; D010959:Tissue Plasminogen Activator / Q000627:therapeutic use*
chemical_list: D001055:Apolipoproteins B; D008055:Lipids; D017270:Lipoprotein(a); D008074:Lipoproteins; D010958:Plasminogen; D010959:Tissue Plasminogen Activator