Calcium-induced inhibition of taurine transport in brush-border membrane vesicles from rabbit small intestine.
The influence of Ca2+ on the activity of the taurine transport system was investigated in rabbit small intestinal brush-border membrane vesicles. Preincubation of the brush-border membrane vesicles with Ca2+ prepared by the Mg2(+)-aggregation method markedly decreased the NaCl gradient-dependent uptake of taurine in these vesicles. Uptake of glucose and alanine, both dependent on a Na+ gradient, were also decreased by Ca2(+)-treatment, but their reduction was very small compared with that of taurine uptake. The inhibitory effect of Ca2+ was dose- and time-dependent. The inhibition was reduced by the presence of ethylene glycol-bis(beta-amino ethyl ether)-N,N,N'-N'-tetraacetic acid during treatment of the membrane vesicles with Ca2+. Neomycin partially protected the taurine transporter activity from the Ca2(+)-induced inhibition, but indomethacin did not. 5-Nitro-2-(3-phenylpropylamino)benzoate, a Cl(-)-channel blocker, did not increase taurine uptake in the Ca2(+)-treated membrane vesicles. It is concluded that the Ca2(+)-induced inhibition of taurine uptake in rabbit intestinal brush-border membrane vesicles is not due to accelerated dissipation of the ion gradient driving forces across the membrane but rather to a direct effect on the transporter, most likely mediated by the activation of the membrane-bound phospholipase C.
Miyamoto
Y
Y
Department of Cell and Molecular Biology, Medical College of Georgia, Augusta 30912-2100.
Kulanthaivel
P
P
Ganapathy
V
V
Whitford
G M
GM
Leibach
F H
FH
D000409:Alanine / Q000378:metabolism; D026905:Amino Acid Transport Systems; D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000008:administration & dosage / Q000494:pharmacology*; D002352:Carrier Proteins / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism; D007213:Indomethacin / Q000494:pharmacology; D007421:Intestine, Small / Q000187:drug effects / Q000378:metabolism*; D008274:Magnesium / Q000008:administration & dosage / Q000494:pharmacology; D008871:Microvilli / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D009355:Neomycin / Q000494:pharmacology; D009579:Nitrobenzoates / Q000494:pharmacology; D011817:Rabbits; D013654:Taurine / Q000378:metabolism*; D010738:Type C Phospholipases / Q000378:metabolism
D026905:Amino Acid Transport Systems; D002352:Carrier Proteins; D009579:Nitrobenzoates; D013654:Taurine; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; D004533:Egtazic Acid; D010738:Type C Phospholipases; D009355:Neomycin; D008274:Magnesium; D005947:Glucose; D000409:Alanine; D002118:Calcium; D007213:Indomethacin