The release of vasoactive substances, 6-keto-prostaglandin F1α (stable marker of prostaglandin I2), endothelin-1, and nitric oxide, was significantly influenced by the incubation with the peptide VPL compared with control cells (P < 0.05), as shown in Table 1.
  Table 1 Relative concentrations of vasoactive substances per milligram of cell protein in cell medium of human aortic endothelial cells treated with various di- and tripeptides compared to untreated cells a.
 Peptides
  | Concentration | Relative concentration of vasoactive substances (% of control)
  |  TXB2 (control = 100 ± 11)
  | 6-keto-PGF1α (control = 105 ± 15)
  | ET-1 (control = 100 ± 19)
  | NO (control = 100 ± 29)
  |  H-Val-Pro-Leu-OH
  | 100 nM | 101 ± 30
  | 124 ± 10*
  | 184 ± 21*
  | 195 ± 38* |  | 50 μM | 108 ± 49
  | 135 ± 42
  | 160 ± 46*
  | 198 ± 49*
  |  a Results are means ± SD for n=6. * Different from untreated cells; P < 0.05. |    |