The ultimate goals of this project are to 1) identify and characterize ion transport pathways in the ileum; 2) to determine how these transporters are regulated, and altered in diarrheal diseases; and 3) to determine the role of anion exchange in organic acid transport by the colon. We will separate villus cells from crypt cells in the ileum using intra-arterial and intraluminal perfusion of calcium chelators. We will prepare brush border and basolateral membranes from these two cell populations using cation precipitation and sucrose density gradient centrifugation techniques. We will then identify and characterize ion transport pathways on each membrane from both crypt and villus cells using the rapid filtration technique and fluorescent probes. Studies to determine if modifier sites are present on a given transporter, that can allosterically activate the transporter, will be performed. After having identified normal transport pathways, we will determine how they are regulated and altered in pathological states. Animal models of diarrhea will include coccidia-infected animals, diabetic animals, glucocorticoid-depleted animals, and 6-OH-dopamine treated animals. The effect of enterotoxins and neurohumoral agents known to affect ion transport will be determined. The effect of protein kinases will be determined. Finally, the role of anion exchange in organic acid transport by the colon will be determined.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK031969-06
Application #
3230443
Study Section
General Medicine A Subcommittee 2 (GMA)
Project Start
1982-12-01
Project End
1991-11-30
Budget Start
1987-12-01
Budget End
1988-11-30
Support Year
6
Fiscal Year
1988
Total Cost
Indirect Cost
Name
Yale University
Department
Type
Schools of Medicine
DUNS #
082359691
City
New Haven
State
CT
Country
United States
Zip Code
06520
Knickelbein, R G; Aronson, P S; Dobbins, J W (1990) Characterization of Na(+)-H+ exchangers on villus cells in rabbit ileum. Am J Physiol 259:G802-6
Knickelbein, R G; Aronson, P S; Dobbins, J W (1988) Membrane distribution of sodium-hydrogen and chloride-bicarbonate exchangers in crypt and villus cell membranes from rabbit ileum. J Clin Invest 82:2158-63