| Abstract: | Gastrin release of porcine gastrin releasing peptide (pGRP) and its related peptides were evaluated. The concentration of serum gastrin after intravenous administration of the peptides was measured by a radio immunoassay. Among pGRP and its related peptides, pGRP was found to retain full bombesin potency with respect gastrin release. The carboxy-terminal fragments of pGRP, 14-27, 18-27, and 19-27 were equipotent for gastrin release, though the peak value of serum gastrin caused by each of these three fragments was significantly less than that evoked by pGRP. The pGRP fragment 20-27, despite showing considerably lesser potency, still evoked statistically significant levels of serum gastrin during its infusion. On the other hand, pGRP fragments 21-27 and 1-13 did not exhibit any appreciable activity. It was concluded that the carboxy-terminal octapeptide 20-27 constitutes the vital active core for gastrin releasing activity of the pGRP molecule. The amino-terminal tridecapeptide pGRP (1-13), while itself inactive, appeared to be important for the full active of pGRP. |
