TY - JOUR
T1 - Selective Decreases in Levels of mRNA Encoding a Water Channel (AQP3) in Ileal Mucosa after Ileostomy in the Rat
AU - Purdy, M. Jennifer
AU - Cima, Robert R.
AU - Doble, Marc A.
AU - Klein, Michael A.
AU - Zinner, Michael J.
AU - Soybel, David I.
N1 - Funding Information:
Of the isoforms cloned and characterized thus far, only AQP3 has been detected with certainty in the mucosa of the small intestine. However, its physiologic role in the intestine remains relatively unexplored. The basolateral localization 4,5 of AQP3 suggests that it may play a role in maintaining cell volume and osmotic equilibrium of the intestinal epithelium, especially during high rates of salt and solute absorption from the lumen. This study was undertaken to (i) evaluate regional differences in gene expression of AQP3 in the small intestine of the rat and (2) determine whether the presence or absence of luminal contents influences AQP3 expression in the distal Surgery (M.J.P., R.R.C., M.A.D., M.J.Z., and D.I.S.) and Pathology (M.A.K.), West RoxburyV eterans Administration Medical Center, Harvard Medical School, Boston, Mass. Supported by the Brigham Surgical Group Fotmdation, an Ethicon-SUS Research Fellowship Award (M.J.P.), and National Institutes of Health Awards T32-DK-09288-02 (R.R.C.) and ROI-DK 44571-02 (D.I.S.). Reprints requests: David I. Soybel, M.D., Department of Surgery/112, West Roxbury Veterans Administration Medical Center, 1400 VFW Parkway, West Roxbury,M A 02132. E-mail: [email protected]
PY - 1999
Y1 - 1999
N2 - Water channels (aquaporins) provide pathways for water permeation in a variety of epithelia. Aquaporin-3 (AQP3) has been localized to the basolateral membranes of epithelial cells in the small intestine, but mechanisms that regulate its expression and function have not been explored. To determine whether luminal content may influence intestinal AQP3 gene expression, adult Sprague-Dawley rats underwent sham laparotomy (N = 11) or loop ileostomy (N = 9) and were killed 8 days after procedures. Northern blot analysis was used to measure messenger RNA (mRNA) levels for AQP3 and the Na+/K+ ATPase, a housekeeping transporter that regulates cellular levels of Na+ and K+. At sacrifice, histologic examination revealed only minimal changes in mucosal morphology. In sham animals, Na/K mRNA levels increased moderately in distal regions of the small intestine. Ileostomy did not alter these levels in any region. In contrast, in sham animals, AQP3 mRNA levels increased along the length of the intestine and were markedly higher in the distal ileum. Diversion of luminal contents decreased AQP3 mRNA levels in the postileostomy region by 30% to 50%. These findings indicate regional variations in expression of the AQP3 water channel in mucosa of the small intestine. In addition, they suggest that AQP3 gene expression may depend on the presence of luminal contents.
AB - Water channels (aquaporins) provide pathways for water permeation in a variety of epithelia. Aquaporin-3 (AQP3) has been localized to the basolateral membranes of epithelial cells in the small intestine, but mechanisms that regulate its expression and function have not been explored. To determine whether luminal content may influence intestinal AQP3 gene expression, adult Sprague-Dawley rats underwent sham laparotomy (N = 11) or loop ileostomy (N = 9) and were killed 8 days after procedures. Northern blot analysis was used to measure messenger RNA (mRNA) levels for AQP3 and the Na+/K+ ATPase, a housekeeping transporter that regulates cellular levels of Na+ and K+. At sacrifice, histologic examination revealed only minimal changes in mucosal morphology. In sham animals, Na/K mRNA levels increased moderately in distal regions of the small intestine. Ileostomy did not alter these levels in any region. In contrast, in sham animals, AQP3 mRNA levels increased along the length of the intestine and were markedly higher in the distal ileum. Diversion of luminal contents decreased AQP3 mRNA levels in the postileostomy region by 30% to 50%. These findings indicate regional variations in expression of the AQP3 water channel in mucosa of the small intestine. In addition, they suggest that AQP3 gene expression may depend on the presence of luminal contents.
UR - http://www.scopus.com/inward/record.url?scp=0032600284&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0032600284&partnerID=8YFLogxK
U2 - 10.1016/S1091-255X(99)80009-2
DO - 10.1016/S1091-255X(99)80009-2
M3 - Article
C2 - 10457325
AN - SCOPUS:0032600284
SN - 1091-255X
VL - 3
SP - 54
EP - 60
JO - Journal of Gastrointestinal Surgery
JF - Journal of Gastrointestinal Surgery
IS - 1
ER -