Cyclooxygenase blockade and exogenous glutamine enhance sodium absorption in infected bovine ileum.
We have previously shown that prostanoids inhibit electroneutral sodium absorption in Cryptosporidium parvum-infected porcine ileum, whereas glutamine stimulates electroneutral sodium absorption. We postulated that glutamine would stimulate sodium absorption via a cyclooxygenase (COX)-dependent pathway. We tested this hypothesis in C. parvum-infected calves, which are the natural hosts of cryptosporidiosis. Tissues from healthy and infected calves were studied in Ussing chambers and analyzed via immunohistochemistry and Western blots. Treatment of infected tissue with selective COX inhibitors revealed that COX-1 and -2 must be blocked to restore electroneutral sodium absorption, although the transporter involved did not appear to be the expected Na(+)/H(+) exchanger 3 isoform. Glutamine addition also stimulated sodium absorption in calf tissue, but although this transport was electroneutral in healthy tissue, sodium absorption was electrogenic in infected tissue and was additive to sodium transport uncovered by COX inhibition. Blockade of both COX isoforms is necessary to release the prostaglandin-mediated inhibition of electroneutral sodium uptake in C. parvum-infected calf ileal tissue, whereas glutamine increases sodium uptake by an electrogenic mechanism in this same tissue.
Cole
Jeffrey
J
Department of Molecular Biomedical Sciences, North Carolina State University, Raleigh, NC 27695, USA. jtcole@unity.ncsu.edu
Blikslager
Anthony
A
Hunt
Elaine
E
Gookin
Jody
J
Argenzio
Robert
R
D000818:Animals; D001693:Biological Transport, Active; D015153:Blotting, Western; D002417:Cattle; D002713:Chlorine; D003457:Cryptosporidiosis / Q000378:metabolism* / Q000469:parasitology; D016785:Cryptosporidium parvum; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D005973:Glutamine / Q000494:pharmacology*; D007082:Ileum / Q000378:metabolism* / Q000469:parasitology / Q000473:pathology; D007249:Inflammation / Q000473:pathology; D007408:Intestinal Absorption / Q000187:drug effects* / Q000502:physiology*; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D011868:Radioisotopes; D012964:Sodium / Q000378:metabolism*; D012979:Sodium Radioisotopes; D016707:Tissue Fixation
D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D007527:Isoenzymes; D011868:Radioisotopes; D012979:Sodium Radioisotopes; D005973:Glutamine; D002713:Chlorine; D012964:Sodium; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases