Observations on the pathway of exogenous C14-histamine in stimulating gastric secretion*

Summary o 1. After injection of C 14 -histamine, radioactivity was determined simultaneously in the gastric, duodenal and rectal mucosa, gastric juice and serum of the dog. 2. The acid secretion was measured simultaneously with the above studies. 3. When gastric secretion had ceased, the level of radioactivity in the gastric mucosa and serum was still moderately high. 4. The level of radioactivity in the gastric duodenal and rectal mucosa correlated well with the known levels of endogenous histamine in these organs. 5. After the C 14 -histamine induced secretion had ceased for one hour, stimulation with the same dose of unlabeled histamine increased the radioactivity of the juice above previous levels.