Interaction of cadmium with brush border membrane vesicles from the rat small intestine.
Cd2+ uptake by brush border membrane vesicles isolated from rat small intestine was investigated by a rapid filtration technique. Cd2+ uptake showed time- and temperature-dependence. Changes in medium osmolarity had no effect on Cd2+ uptake, indicating that the process involves primarily binding of Cd2+ to membrane component(s). Membrane-impermeable chelating agents removed only about 60-65% of the bound cadmium from intact vesicles preincubated with Cd; almost all Cd was removed by chelators when membrane permeability was increased by 1-butanol. Thus Cd uptake by membrane vesicles results in binding to both sides of the membrane. Pretreatment of vesicles with cadmium resulted in a time-dependent inhibition of D-glucose uptake in the presence of a sodium (but no potassium) gradient. This inhibition is correlated with Cd binding to external sites on the D-glucose transporter, and not the driving force for D-glucose transport.
Bevan
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C
Department of Environmental Health, University of Cincinnati, College of Medicine, OH 45267-0056.
Foulkes
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EC
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002104:Cadmium / Q000378:metabolism* / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism; D004492:Edetic Acid; D005947:Glucose / Q000378:metabolism; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000378:metabolism; D007421:Intestine, Small / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008871:Microvilli / Q000378:metabolism* / Q000648:ultrastructure; D010539:Permeability; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000494:pharmacology; D013393:Sucrase / Q000032:analysis; D013696:Temperature
D002104:Cadmium; D004492:Edetic Acid; D012964:Sodium; D013393:Sucrase; D005947:Glucose