The Effect of the Vagus Nerve on Extragastric Gastrin Secretion

The present studies were carried out to assess the function of the vagus nerve in the release of extragastic gastrin. A Clinical Studies 1. In patients with cancer of the stomach, the serum gastrin levels were determined before and 1, 10, 20 and 30 days, respectively, after distal and total gastrectomics. In patients who undergone pancreatoduodenectomies due to cancer of the pancreatic head, the above measurements were also performed. Only in cases of total gastrectomy, was a truncal vagotomy done. 2. In healthy men and in patirnts who had undergone distal, proximal or total gastrectomies, or pancreatoduodenectomies about one month previously, the serum gastrin levels were determined before and 15, 30, 60, 90 and 120 minutes, respectively, after the intravenous administration of regular insulin, 0.25u/kg. Truncal vagotomies had been performed in the patients who had proximal and total gastr ectomies. 3. Results. i) After removal of the antrum, a compensatory hyperfunction of the extragastric gastrin system developed more rapidly, markedly in non-vagotomized patients (distal gastrectomy) than in vagotomized ones (total gastrectomy) ⅱ) In spite of the preservation of the vagus nerves, the serum gastrin levels which had fallen markedly immediately after pancreatoduodenectomy, i.e., removal of the antrum and duodenum, remained almost unchanged thereafter. ⅲ) After hypoglycemic vagal stimulation, regardless of whether the antrum was present or not, when the vagus preserved, a considerable increase in serum gastrin was found. ⅳ) The vagal stimulation induced by the insulin injection produced little changes in the serum gastrin levels after pancreatoduodenectomy. B. Experimental Studies 1. In dogs, the following procedures were performed : ⅰ) No gastrectomy. ⅱ) Distal hemi-gastrectomy. The gastic and duodenal stumps were closed separately. The animals in this group were subjected to the experiment one hour postoperatively. ⅲ) The same operation as No, ⅱ However, the gastic and duodenal stumps were anastomosed. The animals in this group were subjected to the experiment three months postperatively. The bilateral vagal trunks were cut off and both distal stumps were simulated for 20 minutes by electrical square waves with a frequency of 50 Hz and a voltage of 15 V. The serum gastri levels were determined before and 5, 10, 20, 30, 45, 60, 90, and 120 minutes, respectively, after the vagal stimulation. 2. The following operations were also performed : ⅰ) ⅱ)and ⅲ) were the same as above. ⅳ) Truncal vagotomy. The animals in this group were subjected to the experiment one hour postoperatively. ⅴ) Distal gastrin with truncal vagotomy. The animals in this group were subjected to the experiment one hour postoperatively. Hypoglycemic vagal stimulation was induced by the intravenous injection of regular insulin, 0.25 u/kg. The serum gastrin levels were determined before and 15, 30, 60, 90, and 120 minutes, respectively after injection. 3 Results. ⅰ) Regardless of whether the antrum was present or not, the serum gastrin levels rose considerably during the entire of electrical vagal stimulation but fell immediately after cessation of the stimulation. Throughout the experiment, the absolute values of the serum gastrin were highest in the group with no gastrectomy (ⅰ), next highest, in the three months after distal hemi-gastrectomy group (ⅲ) and lowest, in the one hour after surgery group (ⅱ). However, the maximum changing rates expressed as percentages of the pre-stimulation values were similar. ⅱ) Without truncal vagotomy, insulim stimulation produced considerable changes in the serum gastrin levels, regardless of the existence of the antrum, but with vagotomy, few changes occurred. The absolute values and changing rates of serum gastrin were higher three months after distal gastrectomy than one hour after the same operation. Conclusion. It was demonstrated clinically as well as experimentally that the vagus nerves assist a compensatory hyperfunction of the extragastic gastrin system after removal of the antrum. It was also shown that vagal stimulation promotes the secretion of extragastric gastrin.