HEPATIC AND INTESTINAL ELIMINATION OF ENDOGENOUS GASTRIN IN PIGS

The elimination of endogenous carboxyamidated and glycine-extended gas trins in liver and gut was studied before and after feeding in 14 anes thetized pigs. Before the meal, liver and gut extractions were nonsign ificant. 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 e xtracted significant amounts of amidated gastrin, while the intestinal extraction remained nonsignificant. The postprandial hepatic extracti on ratio increased from 0.09 +/- 0.04 to 0.18 +/- 0.04 (p < 0.01). Bef ore feeding, the hepatic and extrahepatic clearance rates were 80.0 +/ - 38.7 and 232.3 +/- 77.7 ml/min. Clearance rates after feeding were 1 44.8 +/- 29.5 (p < 0.01) and 326.4 +/- 75.3 ml/min (NS), respectively. Portal plasma displayed a small postprandial increase in the concentr ation of glycine-extended gastrin, but extraction over the liver and g ut remained nonsignificant. Gel chromatography of portal plasma showed that the fraction of postprandial amidated gastrin corresponded to ga strin-17. The concentration of glycine-extended gastrin was too low fo r chromatographic analysis. We conclude that endogenous amidated gastr in is eliminated in the liver after feeding in pigs.