Differential regulation of cholera toxin-inhibited Na-H exchange isoforms by butyrate in rat ileum
Subramanya, SB; Rajendran, VM; Srinivasan, P; Kumar, NSN; Ramakrishna, BS; Binder, HJ
HERO ID
1457753
Reference Type
Journal Article
Year
2007
Language
English
PMID
| HERO ID | 1457753 |
|---|---|
| In Press | No |
| Year | 2007 |
| Title | Differential regulation of cholera toxin-inhibited Na-H exchange isoforms by butyrate in rat ileum |
| Authors | Subramanya, SB; Rajendran, VM; Srinivasan, P; Kumar, NSN; Ramakrishna, BS; Binder, HJ |
| Journal | American Journal of Physiology: Gastrointestinal and Liver Physiology |
| Volume | 293 |
| Issue | 4 |
| Page Numbers | G857-G863 |
| Abstract | Electroneutral Na absorption occurs in the intestine via sodium-hydrogen exchanger (NHE) isoforms NHE2 and NHE3. Bicarbonate and butyrate both stimulate electroneutral Na absorption through NHE. Bicarbonate- but not butyrate-dependent Na absorption is inhibited by cholera toxin (CT). Long-term exposure to butyrate also influences expression of apical membrane proteins in epithelial cells. These studies investigated the effects of short- and long-term in vivo exposure to butyrate on apical membrane NHE and mRNA, protein expression, and activity in rat ileal epithelium that had been exposed to CT. Ileal loops were exposed to CT in vivo for 5 h and apical membrane vesicles were isolated. 22Na uptake was measured by using the inhibitor HOE694 to identify NHE2 and NHE3 activity, and Western blot analyses were performed. CT reduced total NHE activity by 70% in apical membrane vesicles with inhibition of both NHE2 and NHE3. Reduced NHE3 activity and protein expression remained low following removal of CT but increased to control values following incubation of the ileal loop with butyrate for 2 h. In parallel there was a 40% decrease in CT-induced increase in cAMP content. In contrast, NHE2 activity partially increased following removal of CT and was further increased to control levels by butyrate. NHE2 protein expression did not parallel its activity. Neither NHE2 nor NHE3 mRNA content were affected by CT or butyrate. These results indicate that CT has varying effects on the two apical NHE isoforms, inhibiting NHE2 activity without altering its protein expression and reducing both NHE3 activity and protein expression. Butyrate restores both CT-inhibited NHE2 and NHE3 activities to normal levels but via different mechanisms. |
| Doi | 10.1152/ajpgi.00462.2006 |
| Pmid | 17690171 |
| Wosid | WOS:000249995200024 |
| Is Certified Translation | No |
| Dupe Override | No |
| Comments | Source: Web of Science WOS:000249995200024 |
| Is Public | Yes |
| Language Text | English |
| Keyword | ileal mucosa; apical membrane vesicles; Na-22 uptake; NHE2 and NHE3 isoforms; protein expression; differential regulation |