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Porcine gastric inhibitory polypeptide is a 43 amino acid residue polypeptide with the amino acid sequence Tyr–Ala–Glu–Gly–Thr–Phe–Ile–Ser–Asp–Tyr–Ser–Ile–Ala–Met–Asp–Lys–Ile–Arg–Gln–Gln–Asp–Phe–Val–Asn–Trp–Leu–Leu–Ala–Gln–Gln–Lys–Gly–Lys–Lys–Ser–Asp–Trp–Lys–His–Asn–Ile–Thr–Gln. Fifteen of the first 26 amino acids occur in the same position as they do in porcine glucagon, and nine of the first 26 in the same position as in porcine secretin. The calculated molecular weight of the polypeptide is 5105.

BROWN, J. C., MUTT, V., and DRYBURGH, J. R. 1971. The further purification of motilin, a gastric motor activity stitnulating polypeptide from the mucosa of the small intestine of hogs. Can. J. Physiol. Pharmacol. 49,[399][400][401][402][403][404][405] A polypeptide has been isolated from the duodenal mucosa of hogs and has been named motilin. Motilin stimulates motor activity in both antral and fundic gland area pouches of the stomach of dogs. Pt will stimulate pepsin output, with no change in H' secretion, from fundic gland area pouches. Motilin differs from the other characterized gastrointestinal polypeptides both chemically and in its physiological actions. In particular, the presence of phenylalanine as N-terminal residue, the absence of histidine, and presence of large amounts of glutamic acid and glutamine distinguish it from cholecystokinin-pancreozymin and secretin. BROWN, b. C., MUTT, V.. et DRYRURGII. J . W. 1971. The further purification of motilin, a gastric motor activity stinmulating polypeptide from the nmucosra of the small intestine of hogs. Can. J. Physiol. Pharnmacol. 49, 399-4135.Wous avons is016 B partir de la muqueuse duodenale de porc. un polypeptide que nous avons nomrnk motiline. I1 stimufe la motilitC des poches de I'antre pylorique et du fundus de l'estornac de chien. I1 stirnule kgalernent la libkration de pepsine sans motifier la skcrbtion d'H+ B partir des aires ~Ccrbtrices du fundus. La motiline diffhre des autres polypeptides gastro-intestinaux dbjB connus par caractCristiques chimiques et ses actions physiologiques. En particulier. les caract2res qui le distinguent de la s@cr@tine et du CCK-PZ sont la prCsence de phbnylalanine csmme rksidu N-terminal, l'ahsence d'histidine et l'abondance de glutamine et d'acide glutanmique.

Using a recently validated radioimmunoassay, changes in circulating somatostatin have been measured in normal subjects after food (a standard breakfast), and oral and intravenous glucose. After the standard breakfast, a clear and sustained rise in plasma somatostatin was seen in all subjects from a mean value (+/-1 SE) of 28 +/- 7 pg/ml to a mean peak value, at 60 min of 57 +/- 11 pg/ml. When glucose was taken by mouth a significant but smaller rise was seen, but intravenous glucose caused no significant change in plasma somatostatin. A rise in circulating somatostatin after feeding has not previously been demonstrated in normal man and it is suggested that somatostatin may have an important endocrine role in the gut.

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Studies were carried out in conscious dogs in which the effect of intravenous somatostatin on immunoreactive gastric inhibitory polypeptide (IR-GIP) release was investigated. In addition, the inhibitory action of somatostatin on the insulin response to pure porcine GIP was assessed. Intravenous administration of somatostatin resulted in a delayed IR-GIP and immunoreactive insulin (IRI) response to oral glucose. Somatostatin also delayed the IR-GIP response to the ingestion of fat. In both types of experiments, initial depression of IRI levels was followed by a sharp rise in IRI release. Intravenous infusion of somatostatin produced 80% inhibition of the IRI response to pure porcine GIP. It was concluded that somatostatin inhibits the physiological release of IR-GIP and the insulinotropic action of exogenous porcine GIP.