Most studies of gastric secretory function have been focused on the regulation of acid-peptic secretions. Another important aspect of gastric physiology, namely that of secretion of mucus has received scant attention. Our goal in this program of investigations was to determine what agencies influence the secretory rate and the composition of mucus. The influence of the autonomic nervous system was a logical avenue of investigation since previous studies in humans by Glass' and, in animals, by Jennings and Florey2 and by DeGraef3 have suggested that vagal stimulation increases gastric secretion of mucus.In addition, the influence of feeding on the secretion of antral mucus was studied to determine whether this function is under a neural and humoral control similar to that of gastric HC1 secretion. Hormonal influences-glucocorticoids, parathyroid hormone and serotonin-on various parameters of mucous secretion were also investigated. MATERIALS AND METHODSPreviously reported methods of studying mucus were u~e d .~,~ Mucous secretions were collected from both denervated and innervated canine gastric antral pouches. Vagally denervated pouches were constructed by dividing the stomach at the junction between the corpus and the antrum. The construction of vagallyinnervated pouches was similar but, instead of separating the antrum from the corpus completely, the antral mucosa was undermined circumferentially through a short incision on the anterior wall of the stomach and complete separation of the antral pouch from the main stomach was achieved by constructing a double wall mucosal septum. The pyloric opening of the pouches was fitted with a small plastic cannula brought out through the anterior abdominal wall. Secretions from these pouches were collected by attaching a condom to the cannula. The pH of each sample was estimated by a paper method. The levels were almost always at neutrality. Dogs secreting mucus at a pH below 6.0 were discarded. The volume of each collection was measured and the entire sample was then dialyzed for 24 hr against multiple changes of distilled HzO. At completion of dialysis, each individual sample was shell-frozen and lyophilized. Each freezedried sample was weighed and a measurement of concentration of nondialyzable mucosubstance per ml of mucus was obtained. Aliquots of each freeze-dried sample were analyzed for concentration of nitrogen, hexsosamines,s hexo~es,~ L-fucose,' and sialic acid.* Experiments were conducted with the animals restrained in modsed Pavlov stocks. After an overnight fast, the animal was placed in the stock and two consecutive two-hour samples of mucus were collected. The stimulus under study was given, usually as an intravenous (i.v.) injection, at the end of the first two-hour collection. As a "double control," the same procedure was followed on

It is thought that stress, ACTH and adrenal cortical steroids may be involved in the aetiology of peptic ulceration. Previous work has shown that when ACTH is administered in physiological or therapeutic doses it does not increase gastric acid secretion. We therefore have investigated the effect of ACTH (2 u/kg body wt,) on the ‘mucus barrier’. The volume, weight and concentration of the biochemical constituents of canine gastric mucus were measured before, during and after ACTH administration. No uniform effect of ACTH was detected. Our results differ from those of other workers and the reasons for this are discussed.

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