A possible origin of circulating gastrin component IV in cats.

Blair, E. L.; Grund, E. R.; Lund, P. Kay; Sanders, David J.

doi:10.1113/jphysiol.1977.sp012110

Cited by 18 publications

(11 citation statements)

References 11 publications

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“…Our results show that this assumption is unjustified. In species such as dog and cat, it is already well established that circulating G17 is converted in the circulation to COOH-terminal immunoreactive fragmen4 (13)(14)(15). The main difference between dog, cat, and man lies in the rate of the conversion.…”

Section: °Cmentioning

confidence: 99%

Metabolism of heptadecapeptide gastrin in humans studied by region-specific antisera.

Pauwels¹,

Dockray²,

Walker³

et al. 1985

J. Clin. Invest.

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The metabolism of synthetic human heptadecapeptide gastrin (G17) in vivo, and in serum in vitro, was studied by radjoimmunoassay using region specific antisera, gel filtration, ion exchange chromatography, and high performance liquid chromatography. After infusion of G17 intravenously in normal human volunteers, COOH-terminal and NH2-terminal immunoreactive G17 fragments were generated. At a steady state, -15% of COOH-terminal immunoreactivity was attributable to G14-like material and up to 25% of total NH2-terminal immunoreactivity was attributable to two NH2-terminal fragments; one had the chromatographic properties of 1-13 G17, and the other was less acidic and less hydrophobic. After stopping the infusion of G17, the latter fragments accounted for progressively greater proportions of total gastrin activity. When G17 was incubated in serum in vitro, there was timedependent and temperature-dependent loss of immunoreactivity, and again COOH-terminal and NH2-terminal immunoreactive fragments were formed. Removal of the NH2-terminal pyroglutamic acid was probably the rate limiting step because synthetic 2-17 G17 was degraded more rapidly in serum (tl/2, 2-3 h) than G17 (t1/2, 3-5 h). EDTA blocked degradation at the COOH-terminus of both 2-17 G17 and G17 but cleavage at the NH2-terminus still occurred, giving rise to a G14-like peptide. The rate of conversion of G17 in serum was not enough to account for the production of fragments in vivo, and it is proposed that these are formed when G17 encounters enzymes on cell surfaces, perhaps during passage through the capillary circulation. The production of these fragments needs to be considered in interpreting studies of the identity, metabolism, and release of gastrin in health and disease.

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Section: °Cmentioning

confidence: 99%

Metabolism of heptadecapeptide gastrin in humans studied by region-specific antisera.

Pauwels¹,

Dockray²,

Walker³

et al. 1985

J. Clin. Invest.

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“…Components III and IV are, respectively, thought to correspond with the heptadecapeptide (little gastrin) and tetradecapeptide (minigastrin) forms of the hormone (11). Cat blood in vivo and in vitro will convert little gastrin to component IV (2) . Based on these observations, and the equal biological activity of synthetic human nonsulphated gastrin heptadecapep tide (SHG13NS), SHG16NS, SHG15NS and SHG13NS in the cat, we have argued that minigastrin is a major, physiologically active, circulating form of the hormone in this species (3) .…”

mentioning

confidence: 99%

Equipotency of Little and Minigastrin in the Cat

Hirst¹,

Shaw²

1981

Digestion

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Synthetic human non-sulphated gastrin heptadecapeptide (little gastrin) and tetrade-capeptide (minigastrin) are equipotent stimulants of gastric acid and pepsin secretions in the conscious cat. This supports the thesis that minigastrin is a major physiologically active, circulating form of the hormone in the cat. It is estimated that little gastrin and minigastrin contribute equally to the gastric acid response to a protein meal in the cat.

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“…It is formed from gastrin 17 in cat blood in viva and in vitro but not in human blood in vitro. This conversion is thought to be enzymic (5). The equipotency of fragments of gastrin with 13 or more amino acid residues with gastrin 17 in the cat (table 111) is unlikely to be the result of the conversion of gastrin 17 to component IV.…”

Section: Discussionmentioning

confidence: 99%

“…During an infusion of SCG17NS in the an aesthetized cat, arterial blood contains signifi cantly greater concentrations of component IV than III (5). Stimulation with meat extract results in equal gastric venous concentrations (2) and peripheral venous concentrations (20) of components III and IV in anaesthetized and conscious cats, respectively.…”

Section: Discussionmentioning

confidence: 99%

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Gastric Acid and Pepsin-Stimulating Activity of Non-Sulphated Fragments of Gastrin in the Cat

et al. 1980

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The gastric acid and pepsin-stimulating activities of several C terminal fragments of non-sulphated human gastrin were investigated in the conscious cat prepared with cannulated gastric fistulae with a reproducible, continuous infusion method to construct dose-response curves. The gastric acid-stimulating activities were quantified by reference to the ED₅₀ and were compared with the activity of synthetic non-sulphated human gastrin 17 (SHG17NS) and cat gastrin 17 (SCG17NS). SHG17NS had an ED₅₀ of 0.329 nmol kg^-1 h^-1. SHG16NS, SHG15NS and SHG13NS all showed similar activities to SHG17NS. SCG17NS tested at low doses had similar activity to SHG17NS. SHG10NS, G5 and G4 and peptavlon showed progressively lower acid-stimulating activities: 26, 12, 9 and 9%, respectively, compared with SHG17NS. The gastric acid-stimulating activities of all the peptides were paralleled by similar pepsin-stimulating activities. The ratios of pepsin secretion:acid secretion were similar for all the peptides (1–2 μgpepsin/μEq H⁺). The results are discussed in relation to the biological activity of the circulating gastrin components in the cat compared with other species and it is argued that component IV (corresponding to gastrin tetradecapeptide or minigastrin) is a major, physiologically active, circulating form of the hormone in the cat.

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A possible origin of circulating gastrin component IV in cats.

Cited by 18 publications

References 11 publications

Metabolism of heptadecapeptide gastrin in humans studied by region-specific antisera.

Metabolism of heptadecapeptide gastrin in humans studied by region-specific antisera.

Equipotency of Little and Minigastrin in the Cat

Gastric Acid and Pepsin-Stimulating Activity of Non-Sulphated Fragments of Gastrin in the Cat

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