Abstract
1. The gastrin concentrations in serum were elevated after nephrectomy in rats and mice indicating the importance of the kidney for elimination of gastrin in these species. In guinea-pigs and rabbits nephrectomy did not cause increased serum gastrin concentrations. In rats there was a gradual rise in the serum gastrin level up to 48 hr after bilateral nephrectomy and also after ureteral ligation. After the latter operation the concentrations of gastrin in serum were lower than after nephrectomy. Significant elevation of the gastrin level 48 hr after ureteral ligation indicates that gastrin is eliminated at least partly through glomerular filtration. The gastric histidine decarboxylase activity after nephrectomy or ureteral ligation generally reflected the concentration of circulating gastrin.
2. After bilateral ureteral ligation gastric acid secretion in conscious fistula rats was uniformly inhibited with no response to pentagastrin or histamine 24 or 48 hr after the operation. After nephrectomy basal acid secretion was reduced and there was no response to pentagastrin. The response to histamine was still present, although reduced at all dose levels. Linear transformation of the dose—response curve indicated mixed inhibition. The incidence of gastric ulcer was 75% 48 hr after nephrectomy and 30% after ureteral ligation. Since basal and pentagastrin-stimulated acid secretion were unaffected by nephrectomy in rats with the upper two-thirds of the intestine removed, the intestine appears to produce factors which are responsible for the inhibition of gastric secretion.
2. On the whole, the gastrin concentration in serum and gastric histidine decarboxylase activity were not increased after five-sixths nephrectomy. Gastric ulcers were seen in the rats with the highest serum urea levels; one in addition had high serum gastrin concentration and gastric histidine decarboxylase activity. Basal, pentagastrin- and histamine-stimulated acid secretion were not affected by subtotal nephrectomy. It appears that in the rat about one sixth of the renal mass is the minimum required for handling gastrin degradation and excretion.