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The Role of Cl‐ in the basolateral Na+/Mg2+ exchanger using a TPP+ Electrode
Author(s) -
Cefaratti Christie
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a1325-a
Subject(s) - chemistry , vesicle , epithelial polarity , membrane , ion transporter , biophysics , inorganic chemistry , analytical chemistry (journal) , biochemistry , chromatography , biology
We have previously demonstrated that the primary Na+/Mg2+ exchanger in hepatocytes is located on the basolateral membrane. This, as well as the fact that basolateral LPM have no Ca2+/Mg2+ exchanger, are the rationale for all membrane transport data performed with basolateral liver plasma membranes (bLPM). The data shown demonstrates that the time course of accumulation and release of TPP+ by basolateral LPM vesicles loaded with MgCl2 was kinetically measured using a TPP+ electrode. Upon the addition of NaCl there was a time dependent decrease in concentration of extravesicular TPP+ indicating an uptake by the vesicles. The release of TPP+ after it reaches steady state levels by the addition of Na+ is likely accounted for by the fact that there are more charge equivalents transported by Mg2+ efflux than carried by Na+ influx, the deficit being compensated by TPP+ accumulation. The time course of TPP+ electrode measurements but in the absence of Cl‐. Under these conditions, a TPP+ accumulation can not be detected suggesting that the exchange between Mg2+ and Na+ is electroneutral or that the charge equivalents transported by Mg2+ are the same as that carried by Na+. These results are consistent with the results demonstrated in Table 1 (below) as well as data obtained using 3H‐TPP+. NIH‐HL 18708