GLUTAMINE STIMULATES PROSTAGLANDIN-SENSITIVE NA+-H+ EXCHANGE IN EXPERIMENTAL PORCINE CRYPTOSPORIDIOSIS

Background/Aims: Recent studies of piglet cryptosporidiosis showed an injury-induced impairment of sodium-glucose cotransport and a prostaglandin-mediated inhibition of neutral NaCl absorption. Because glutamine has been shown to stimulate both neutral and electrogenic Na+ absorption, this study examined the mechanism of prostaglandin-mediated inhibition of NaCl absorption and the effect of glutamine on these processes. Methods: Ileal mucosa from control and infected pigs was mounted in Ussing chambers for flux studies or incubated with [14C]glutamine or [14C]-glucose for metabolism studies. Results: Glucose and glutamine induced equivalent increases, 2-2.5 μEq·cm-2·h-1, in Na+ absorption and short-circuit current in control ileum. Despite a reduction in villous surface area to one third of the control, glutamine enhanced both neutral and electrogenic Na+ absorption in the infected ileum by 3.5 ± 0.5 μEq·cm-2·h-1, whereas glucose was only half as effective (P < 0.05). In addition, glutamine was oxidized to CO2 at rates three times those of glucose. Indomethacin enhanced, whereas amiloride, prostaglandin E2, and Cl-free solutions inhibited the glutamine-induced neutral Na+ transport. Conclusions: Glutamine-stimulated neutral Na+ absorption is mediated by a prostaglandin-sensitive apical Na+-H+ exchange mechanism. The heightened Na+-H+ exchange and tissue oxidation of glutamine suggest that glutamine is superior to glucose for use in oral rehydration solutions. © 1994.