Effect of intralumenal cation-exchange resin on excretion of ammonia in rat ileum

Ammonia excretion was studied in rat ileal segments during perfusion of the animal through the saphenous vein. In the first 10 min during and after intravenous infusion of L-glutamine (116 mg/ kg to double arterial glutamine concentration) average net change in lumenal ammonia was 13 ± 8 (S.E.) nmole NH₃/min/g ileum; average net change in ileal venous ammonia was 28 ± 9 nmole NH₃/min/g ileum; and average net change in total ammonia (lumen + ileal vein) was 41 ± 13 compared to —5 ± 10 nmole/ min/g ileum for animals infused with saline P < 0.025. These data suggest that ileal metabolism of arterial glutamine liberates am-monia to both ileal venous blood and intestinal lumen. When a cation-exchange resin which binds ammonia was infused intralu- menally, average net change in lumenal ammonia in the first 10 min during and after intravenous infusion of 116 mg/kg L-gluta- mine was 415 ± 156 nmole NH₃/min/g ileum (p<0.01 compared to value during perfusion of Earle’s solution alone). During the first 10 min during and after glutamine infusion net change in ileal venous plasma ammonia was —8 ± 14 when resin was being perfused through the lumen compared to -1-28 ± 9 nmole/min/g ileum during perfusion of Earle’s solution alone without resin P < 0.05. Thus resin in the small intestine can trap very large amounts of ammonia. Speculation: Ammonia-binding cation-exchange resins may be useful therapeutically in lowering portal venous ammonia and increasing intestinal ammonia excretion in patients with hyperammonemia.