INTESTINAL GLUTAMINE AND AMMONIA METABOLISM DURING CHRONIC HYPERAMMONEMIA INDUCED BY LIVER INSUFFICIENCY

During liver insufficiency, besides portasystemic shunting, high arter ial glutamine concentrations could enhance intestinal glutamine consum ption and ammonia generation, thereby aggravating hyperammonaemia. To investigate this hypothesis, portal drained viscera (intestines) fluxe s and jejunal tissue concentrations of ammonia and glutamine were meas ured in portacaval shunted rats with a ligated bile duct, portacaval s hunted, and sham operated rats, seven and 14 days after surgery, and i n normal unoperated controls. Effects of differences in food intake we re minimised by pair feeding portacaval shunted and sham operated with portacaval shunted rats with biliary obstruction. At both time points , arterial ammonia was increased in the groups with liver insufficienc y. Also, arterial glutamine concentration was raised in all operated g roups compared with normal unoperated controls. At both time points, a mmonia production by portal drained viscera was reduced in portacaval shunted rats with biliary obstruction, portacaval shunted, and sham op erated rats compared with normal unoperated controls, and no major dif ferences were found between these operated groups. At day 7 in all ope rated groups glutamine uptake by portal drained viscera was lower than in normal unoperated controls, but no major differences were found at day 14. These experiments show that ammonia generation by portal drai ned viscera remains unchanged in rats with chronic liver insufficiency despite alterations in arterial glutamine concentrations and intestin al glutamine uptake. The hyperammonaemia seems to be mainly determined by the portasystemic shunting.