Pure human minigastrin: secretory potency and disappearance rate

Area of Science:

• Gastroenterology
• Endocrinology
• Pharmacology

Background:

• Minigastrin (HG-13-I), a 13-amino acid peptide, was recently isolated.
• Gastrin plays a crucial role in regulating gastric acid secretion.
• Understanding the distinct properties of different gastrin forms is essential for physiological and pathological insights.

Purpose of the Study:

• To compare the acid-stimulating potency of human nonsulphated minigastrin (HG-13-I) and heptadecapeptide gastrin (HG-17-I).
• To evaluate the rate of disappearance of HG-13-I from the bloodstream.
• To elucidate the comparative physiology of minigastrin and heptadecapeptide gastrin.

Main Methods:

• Utilized three dogs with gastric fistulae and Heidenhain pouches for experimental analysis.
• Administered pure human natural nonsulphated minigastrin (HG-13-I) and HG-17-I via continuous intravenous infusion.
• Dosed gastrins at 100, 200, 400, and 800 pmol/kg-hr to assess dose-dependent effects.

Main Results:

• Equimolar infusions of HG-13-I and HG-17-I produced comparable increases in serum immunoreactive gastrin.
• HG-13-I demonstrated less than half the potency of HG-17-I in stimulating gastric acid secretion (potency ratio 0.4).
• The half-time for HG-13-I disappearance from blood was 1.8 minutes, with a volume of distribution of 0.17 L/kg, similar to HG-17-I.

Conclusions:

• Minigastrin (HG-13-I) is significantly less potent in stimulating acid secretion compared to heptadecapeptide gastrin (HG-17-I).
• The pharmacokinetic profiles of HG-13-I and HG-17-I are comparable, suggesting differences in potency are not due to elimination rates.
• Further research is warranted to determine the specific physiological and pathophysiological roles of minigastrin.