Characterization of a sodium-dependent magnesium efflux from magnesium-loaded rat pancreatic acinar cells.
This study investigates the mechanism of magnesium (Mg2+) transport (efflux) from the exocrine rat pancreas. Permeabilized pancreatic acini were loaded with Mg2+ by employing a high-Mg2+ (12 mM) buffer containing A23187 (6 microM). Net Mg2+ efflux was measured using the technique of atomic absorbance spectrophotometry. Incubation of preloaded acini in a buffer deficient in Mg2+ resulted in a large and time-dependent release of Mg2+ with maximal efflux occurring within 40 min. Pretreatment of loaded acini with bumetanide, SITS or ouabain had no significant effect on Mg2+ efflux. In contrast, when acini were pretreated with 10 mM dinitrophenol, 10(-4) M amiloride, 1 mM lidocaine or 1 mM quinidine there were significant (P < 0.001) decreases in net Mg2+ efflux. Replacement of extracellular sodium [Na+]o with either N-methyl-D-glucamine (NMDG), Tris or choline resulted in a significant (P < 0.001) inhibition of Mg2+ efflux. The results of this study indicate that Mg2+ transport (efflux) in pancreatic acinar cells may not be associated with the Na(+)-K(+)-ATPase, the Na(+)-K(+)-Cl- cotransporter or the anion exchanger, but with a Na(2+)-sensitive Mg2+ transport system.
Wisdom
D M
DM
Department of Applied Biology, University of Central Lancashire, Preston, UK.
Geada
M M
MM
Singh
J
J
D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000494:pharmacology; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport; D002034:Bumetanide / Q000494:pharmacology; D002794:Choline / Q000494:pharmacology; D004140:Dinitrophenols / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D008012:Lidocaine / Q000494:pharmacology; D008274:Magnesium / Q000378:metabolism* / Q000494:pharmacology; D008297:Male; D010042:Ouabain / Q000494:pharmacology; D010179:Pancreas / Q000187:drug effects / Q000378:metabolism*; D011802:Quinidine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
D004140:Dinitrophenols; D002034:Bumetanide; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D010042:Ouabain; D000584:Amiloride; D008012:Lidocaine; D008274:Magnesium; D011802:Quinidine; D002794:Choline