Importance of vagal innervation in the regulatory effect of acid in the duodenum on gastric secretion of acid

Code, Charles F.; Watkinson, G.

doi:10.1113/jphysiol.1955.sp005406

Cited by 128 publications

(31 citation statements)

References 18 publications

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“…The gastric acid receptors described in this paper may initiate these reflex responses. There is convincing evidence that acid in the duodenum reflexly depresses gastric motility and gastric acid secretion via vagal paths [Thomas, Crider and Mogan, 1934;Pincus, Friedman, Thomas and Rehfuss, 1944;Code and Watkinson, 1955;Sircus, personal communication]. The threshold for all these reflex responses was pH 2-5 or less; this is very similar to the threshold for the gastric mucosal acid receptors.…”

Section: Discussionmentioning

confidence: 93%

Gastric Mucosal Chemoreceptors With Vagal Afferent Fibres in the Cat

Iggo

1957

Exp Physiol

153

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Electrical activity was recorded in 19 single fibres, with very slow conduction velocities, dissected from the cervical vagi of 10 cats. The nerve endings of these fibres were in the gastric mucosa and were destroyed when the mucosa was scraped away. A brief burst of impulses was recorded when the mucosa was stroked firmly with a smooth rod but there was no response when the stomach was made to contract, when it was compressed firmly between finger and thumb, or when it was lightly distended. Over-distension excited 3 of the mucosal nerve endings. The mucosal nerve endings were specifically sensitive to either acid or alkaline solutions on the mucosa. The discharge of impulses in the afferent fibre persisted for as long as the stronger solutions used (0-1 N-NaOH or 0-1 N-HCR) remained on the mucosa. The threshold of the acid receptors was pH 3 or lower and of the alkali receptors was pH 8 or above. The endings were not affected by hypotonic or hypertonic solutions or by any other chemicals that were tried. A clear distinction is made between the gastric mucosal nerve endings described in the paper and the tension and "stretch" receptors which are found in the deeper layers of the gastric wall. It is concluded that the mucosal nerve endings probably function as slowly-adapting chemoreceptors.A low-threshold gastric "stretch" receptor is described.Both mechanical and chemical stimulation of the gastric mucosa elicit a variety of sensations and reflex responses. Carlson and Braafladt [1915] and Wolf and Wolff [1947] found that there was a sensation of pressure or an undifferentiated awareness when the normal gastric mucosa of their subjects was rubbed or squeezed; touch, however, was not perceived. Gastric movements in sheep and goats may be enhanced by acidification of the gastric contents [Titchen, 1953] or by mechanical stimulation of the gastric mucosa [see Habel, 1956, for review]. There does not seem to have been any previous electrophysiological account of afferent fibres with endings in the mucosa. The gastric afferent fibres already described came from tension and "stretch" receptors Iggo, 1955. The endings of these fibres were in the outer layers of the gastric wall.The present study is part of a wider investigation of small afferent fibres. It was begun when a gastric afferent fibre was found which did not fit into the category described previously. The ending of the fibre was destroyed when the gastric mucosa was removed. This paper describes the response of similar fibres to mechanical and chemical stimulation. A preliminary account of this work has already appeared [Iggo, 1957 b].

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Section: Discussionmentioning

confidence: 93%

Gastric Mucosal Chemoreceptors With Vagal Afferent Fibres in the Cat

Iggo

1957

Exp Physiol

153

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“…Nevertheless, most observers agree that acid placed in the upper part of the duodenum will inhibit gastric secretion. Code and Watkinson [1955], Longhi, Greenlee, Bravo, Guerre and Dragstedt [1957] and Olbe [1964] found that for inhibition to take place an intact vagus is necessary; Maung Pe Tung and Schofield [1959] suggested that the effect of acid (in the antrum) is to prevent release of gastrin by neural action rather than by releasing an inhibitory substance. Anderson [1960], and Shimizu, Morrison and Harrison [1958] found that acid caused gastric inhibition on both innervated and denervated pouches: Konturek [1970] found that secretin strongly inhibits basal secretion of acid in the stomach.…”

Section: Differentiation Of Elicited From Spontaneous Action Potentialsmentioning

confidence: 99%

“…In normal digestion acid is rapidly neutralized after entering the duodenum but is likely to cause intense, though short-lived, stimulation of type I receptors, with short-lived stimulation of type II receptors. Code and Watkinson [1955] found that continuous acidity in the duodenum provoked vomiting in dogs, and that gastric inhibition was best produced by intermittent infusion of acid. Harper et al [1959] found that strong stimulation for periods of 30 sec of the proximal end of the cut vagus in anaesthetized cats also produced vomiting.…”

Section: Differentiation Of Elicited From Spontaneous Action Potentialsmentioning

confidence: 99%

“…Indirect evidence in favour of such receptors is strong though it is likely that hormonal inhibitors also exist [Konturek, 1970]. Code and Watkinson [1955] reviewed the literature on the presence of nerve receptors and produced further evidence that vagal receptors are present in the dog. Hunt and Knox [1962] demonstrated that when a buffer with a low pH is introduced into the duodenum, there is a delay of gastric emptying in man, and it would seem that the concentration of hydrogen ions, acting on the receptors postulated by Code and Watkinson, provided the stimulus to delay gastric emptying.…”

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confidence: 99%

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Receptors, Activated by Acid, in the Duodenal Wall of Rabbits

Andrews

1971

Exp Physiol

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In anaesthetized rabbits, the effect of introducing acid into the lumen of the duodenum on the frequency of action potentials in the afferent nerves was investigated. Hydrochloric acid, 0.1 and 0 05 M, and acid sodium citrate, buffered with hydrochloric acid to a pH of less than 2, induced action potentials in the distal portions of cut mesenteric nerves coming from the part of the duodenum exposed to the acid. Two types of response were noted from the upper part of the duodenum. One consisted of an intense volley of action potentials beginning almost immediately and lasting for about 15 sec. The other response was less intense; it reached its maximum in about 30 sec and lasted for periods of at least 90 sec. It is postulated that there are two types of nerve receptor in the wall of the duodenum of rabbits which may be stimulated by acid in the lumen, and evidence is presented in favour of the suggestion that the concentration of hydrogen ions is the important factor. The relationship of acid in the duodenum to inhibition of gastric secretion is discussed.Some text books of clinical medicine, for example Bailey and Love [1968], state that there are nervous receptors in the walls of the duodenum, stimulated by a high concentration of hydrogen ions and which cause inhibition of gastric secretion. Indirect evidence in favour of such receptors is strong though it is likely that hormonal inhibitors also exist [Konturek, 1970]. Code and Watkinson [1955] reviewed the literature on the presence of nerve receptors and produced further evidence that vagal receptors are present in the dog. Hunt and Knox [1962] demonstrated that when a buffer with a low pH is introduced into the duodenum, there is a delay of gastric emptying in man, and it would seem that the concentration of hydrogen ions, acting on the receptors postulated by Code and Watkinson, provided the stimulus to delay gastric emptying. In a later paper, however, Hunt and Knox [1969] relate the effect on gastric emptying to the amount of titratable acid, rather than the pH of the gastric contents.Receptors which give rise to action potentials when stimulated by a high hydrogen ion concentration have been demonstrated in the wall of the stomach of the cat by Iggo [1957], but the definitive proofofthe presence of such receptors in the duodenum does not appear to have been published. Although it is difficult to interpret the data collected by various authors except by postulating duodenal 'hydrogen ion receptors' it seemed desirable to see whether the introduction of acid into the duodenum would result in afferent nerve impulses. A preliminary report of the study has been published [Andrews and Andrews, 1970]. METHODS Basically, the method was to introduce acid into the lumen of the duodenum and to measure the number of afferent impulses in the distal portions of cut mesenteric nerves 221

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“…There may possibly be a vagal pathway for the inhibitory effects following feeding. Code & Watkinson (1955) and Schachter (1949), have carried out experiments related to this problem. Schachter considered that the vagus contains secretory-inhibitory fibres in its supply to the stomach, as described by Pavlov (1902).…”

Section: Department Of Physiology University College Londonmentioning

confidence: 99%

Proceedings of the Physiological Society

1958

The Journal of Physiology

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Importance of vagal innervation in the regulatory effect of acid in the duodenum on gastric secretion of acid

Cited by 128 publications

References 18 publications

Gastric Mucosal Chemoreceptors With Vagal Afferent Fibres in the Cat

Gastric Mucosal Chemoreceptors With Vagal Afferent Fibres in the Cat

Receptors, Activated by Acid, in the Duodenal Wall of Rabbits

Proceedings of the Physiological Society

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