Characterization of chicken intestinal brush border membrane Na/H exchange.
1. Na/H exchange is the major pathway for Na uptake in brush border membrane vesicles from chicken small intestine. Hanes-Woolf analysis demonstrated that Na and H competed at the same extravesicular site. The KNa for Na+ at extravesicular pH 6.6 is 35 mM and at pH 7.4, 12 mM. 2. Similar to mammalian intestinal cells, the Na/H exchanger does not appear to have an internal proton modifier site. Varying intravesicular pH from 6.1 to 7.8 stimulates uptake, but a sigmoidal relationship is not observed. 3. The ability of several amiloride analogs to inhibit the exchanger was tested and the inhibitory profile was similar, but not identical to Na/H exchangers in mammalian tissues. The potency series (from most to least potent) is hexamethylamiloride approximately ethylisopropylamiloride > methylisobutylamiloride > dimethylamiloride >> amiloride.
Department of Medicine, University of Chicago, IL 60637.
M W
MW
Musch
C
C
Bookstein
D L
DL
Arvans
E J
EJ
Cragoe
M C
MC
Rao
E B
EB
Chang
D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D002352:Carrier Proteins / Q000187:drug effects / Q000378:metabolism*; D002645:Chickens; D006863:Hydrogen-Ion Concentration; D007421:Intestine, Small / Q000378:metabolism*; D008322:Mammals; D008871:Microvilli / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers
D002352:Carrier Proteins; D017923:Sodium-Hydrogen Exchangers; D000584:Amiloride