Hepatic and intestinal elimination of endogenous gastrin in pigs

The elimination of endogenous carboxyamidated and glycine-extended gastrins in liver and gut was studied before and after feeding in 14 anesthetized pigs. Before the meal, liver and gut extractions were nonsignificant. After feeding, the release rate of amidated gastrin increased from 7.5 +/- 2.6 to 21.9 +/- 5.3 pmol/min (p < 0.02), and the liver extracted significant amounts of amidated gastrin, while the intestinal extraction remained nonsignificant. The postprandial hepatic extraction ratio increased from 0.09 +/- 0.04 to 0.18 +/- 0.04 (p < 0.01). Before feeding, the hepatic and extrahepatic clearance rates were 80.0 +/- 38.7 and 232.3 +/- 77.7 ml/min. Clearance rates after feeding were 144.8 +/- 29.5 (p < 0.01) and 326.4 +/- 75.3 ml/min (NS), respectively. Portal plasma displayed a small postprandial increase in the concentration of glycine-extended gastrin, but extraction over the liver and gut remained nonsignificant. Gel chromatography of portal plasma showed that the fraction of postprandial amidated gastrin corresponded to gastrin-17. The concentration of glycine-extended gastrin was too low for chromatographic analysis. We conclude that endogenous amidated gastrin is eliminated in the liver after feeding in pigs.