Hirschowitz B I, Molina E
Am J Physiol. 1983 May;244(5):G546-51. doi: 10.1152/ajpgi.1983.244.5.G546.
To quantitate bombesin stimulation of gastric acid and pepsin via release of gastrin, five gastric fistula dogs were given graded doses (60-1,250 pmol X kg-1 X h-1) of bombesin tetradecapeptide and 40-2,000 pmol X kg-1 X h-1 of synthetic gastrin-17 (G-17). Acid and pepsin output and serum gastrin were proportional to the dose of stimulant. The half-maximal dose of bombesin for gastrin release was 200 pmol X kg-1 X h-1. Bombesin-stimulated acid secretion related to serum gastrin concentrations was congruent with the G-17 curve, but with a maximum of only 62% of the G-17 maximum before declining by 27% despite higher serum gastrin levels. This suggested that bombesin stimulates acid secretion only via gastrin release and inhibits at higher doses by releasing another inhibitory peptide, most likely somatostatin, which is also released by bombesin. The same mechanism could apply to supramaximal inhibition of acid and pepsin seen with high doses of G-17. Because the pepsin curve related to serum gastrin was to the left of the G-17 curve, we concluded that another secretagogue released by bombesin acts synergistically with gastrin on pepsin secretion. Therefore, bombesin stimulates gastric secretion through gastrin release, but its effects are modified by peptides coreleased to a) increase pepsin output at low doses and b) limit the output of acid and pepsin to 50-60% of the G-17 maximum.
为了通过胃泌素的释放来定量蛙皮素对胃酸和胃蛋白酶的刺激作用，对五只胃瘘犬给予不同剂量（60 - 1250 pmol·kg⁻¹·h⁻¹）的蛙皮素十四肽以及40 - 2000 pmol·kg⁻¹·h⁻¹的合成胃泌素-17（G-17）。胃酸和胃蛋白酶的分泌量以及血清胃泌素水平与刺激物的剂量成正比。蛙皮素促使胃泌素释放的半数最大剂量为200 pmol·kg⁻¹·h⁻¹。蛙皮素刺激的胃酸分泌与血清胃泌素浓度的关系与G-17曲线一致，但尽管血清胃泌素水平较高，其最大分泌量仅为G-17最大分泌量的62%，随后下降了27%。这表明蛙皮素仅通过胃泌素的释放来刺激胃酸分泌，而在高剂量时通过释放另一种抑制性肽（很可能是生长抑素，蛙皮素也能释放生长抑素）来抑制胃酸分泌。相同的机制可能适用于高剂量G-17所见的胃酸和胃蛋白酶的超最大抑制作用。由于与血清胃泌素相关的胃蛋白酶曲线位于G-17曲线的左侧，我们得出结论，蛙皮素释放的另一种促分泌素与胃泌素协同作用于胃蛋白酶的分泌。因此，蛙皮素通过胃泌素的释放来刺激胃分泌，但其作用会被共同释放的肽所改变，以达到以下两个目的：一是在低剂量时增加胃蛋白酶的分泌量；二是将胃酸和胃蛋白酶的分泌量限制在G-17最大分泌量的50 - 60%。
