BACKGROUND: After major hepatectomy, the remaining liver compensates for its reduced mass and maintains euglycemia through increased hepatic glucose output. The mechanism of this compensation may be a diminished hepatic extraction of portal insulin, which thereby decreases the suppressive effects of insulin on gluconeogenesis. METHODS: Extraction of insulin by the liver was measured using the isolated perfused rat liver model. Fasted Sprague-Dawley rats were studied at 1, 2, 3, 4, 6, and 14 days after 70% hepatectomy. Control rats had no operation, and sham rats were studied 1 day after a sham laparotomy. The difference between portal and caval insulin concentrations was determined and reported as micromoles of insulin extracted per gram liver per minute. RESULTS: Insulin extraction decreased from 191 +/- 22 microU/gm liver/min in control rats to 87 +/- 13.2 microU/gm liver/min at postoperative day 1 (p = 0.0001). Extraction normalized by postoperative day 6. Extraction rates in rats recovering from sham laparotomy were similar to control rats (p = 0.088), suggesting that decreased extraction in hepatectomized rats was not due to postoperative stress. CONCLUSIONS: After 70% hepatectomy, the remaining liver extracts less insulin per gram. This may explain the ability of the reduced liver mass to maintain euglycemia after major hepatectomy.
BACKGROUND: After major hepatectomy, the remaining liver compensates for its reduced mass and maintains euglycemia through increased hepatic glucose output. The mechanism of this compensation may be a diminished hepatic extraction of portal insulin, which thereby decreases the suppressive effects of insulin on gluconeogenesis. METHODS: Extraction of insulin by the liver was measured using the isolated perfused rat liver model. Fasted Sprague-Dawley rats were studied at 1, 2, 3, 4, 6, and 14 days after 70% hepatectomy. Control rats had no operation, and sham rats were studied 1 day after a sham laparotomy. The difference between portal and caval insulin concentrations was determined and reported as micromoles of insulin extracted per gram liver per minute. RESULTS: Insulin extraction decreased from 191 +/- 22 microU/gm liver/min in control rats to 87 +/- 13.2 microU/gm liver/min at postoperative day 1 (p = 0.0001). Extraction normalized by postoperative day 6. Extraction rates in rats recovering from sham laparotomy were similar to control rats (p = 0.088), suggesting that decreased extraction in hepatectomized rats was not due to postoperative stress. CONCLUSIONS: After 70% hepatectomy, the remaining liver extracts less insulin per gram. This may explain the ability of the reduced liver mass to maintain euglycemia after major hepatectomy.