Some Properties Shared by Amino Acids and Entero-oxyntin

Abstract

The intestinal phase of gastric secretion has been thought to be due to the release of a hormone from the gut mucosa, and several properties have been attributed to this as-yet unidentified hormone. An amino acid solution, known to stimulate gastric secretion, was tested to see if it possesses several of these properties, i.e., inactivation by the liver, and the ability to augment the maximum responses to pentagastrin and histamine. In six dogs with Heidenhain pouches the gastric secretory responses to peripheral and portal intravenous administration of a solution of mixed L-amino acids were measured. The mean peak response of three such separate peripheral infusions in each dog was 370 microEq/30 minutes while the peak response to intraportal infusion was only 45 microEq/30 minutes (p < .05). In three dogs with Heidenhain pouches the intravenous administration of amino acids together with pentagastrin resulted in significant augmentation of the peak response to pentagastrin alone (p < .025). Similarly, administration of amino acids with histamine resulted in augmentation of the peak response to histamine alone (p < .05). Because amino acids mimic the actions of the "intestinal phase hormone" in these respects it is suggested that they may account, at least in part, for the intestinal phase of gastric secretion. In addition, amino acids absorbed during protein digestion may contribute to the gastric hypersecretion which is regularly seen with portosystemic shunts.

Inhibition of gastric acid secretion by intestinal and parenteral administration of a mixture of L‐amino acids in the Atlantic cod, Gadus morhua

“…The degree of inhibition was related to the attained level of plasma amino nitrogen but independent of the administration route. This result is at variance with findings in mammals, where mixtures of AA, intestinal as well as systemic, stimulate gastric acid secretion (Landor & Ipapo 1977, Landor et al 1980, Isenberg & Maxwell 1978, Mariano et al 1978. Concerning the present results, it cannot be excluded that an inhibitory principle is released from the intestine following luminal stimula-Financial support was received from the Swedish Natural Science Research Council (B-BU 4257-103), Magn.…”

The intestinal phase hormone

“…Systemic intravenous administration of amino acids in dogs and humans has been shown to stimulate acid secretion from the innervated and denervated stomach to the same extent as instillation of amino acids in the duodenum or jejunum [101,107,109,115,117,[122][123][124], and to produce no changes in serum gastrin concentration [109,115,117,122]. Administration of amino acids by the portal venous route in dogs has been observed to have little or no gastric stimulatory effect, in contrast to systemic administration [109,123]. Interestingly, intraduodenal administration of amino acids in dogs and humans has been found, predictably, to result in a much lower level of amino nitrogen in peripheral blood than systemic administration, but to stimulate gastric acid secretion to the same degree [109,115,117].…”

“…It is well established that amino acids are capable of directly stimulating the parietal cell [121]. Systemic intravenous administration of amino acids in dogs and humans has been shown to stimulate acid secretion from the innervated and denervated stomach to the same extent as instillation of amino acids in the duodenum or jejunum [101,107,109,115,117,[122][123][124], and to produce no changes in serum gastrin concentration [109,115,117,122]. Administration of amino acids by the portal venous route in dogs has been observed to have little or no gastric stimulatory effect, in contrast to systemic administration [109,123].…”

“…Interestingly, intraduodenal administration of amino acids in dogs and humans has been found, predictably, to result in a much lower level of amino nitrogen in peripheral blood than systemic administration, but to stimulate gastric acid secretion to the same degree [109,115,117]. One study in dogs [123], which requires confirmation, was reported to show augmentation by systemic intravenous amino acid administration of the maximal acid secretory response to pentagastrin and histamine, while a similar study in humans [117] failed to show augmentation of the maximal pentagastrin response. Although absorption of amino acids could account for some of the gastric secretory response to food in the intestine, this phenomenon cannot explain the gastric secretory response to balloon distention of the intestines that has been conclusively demonstrated in dogs and humans [9,10,92,95].…”