AE anion exchangers in atrial tumor cells

Papageorgiou, Panos, Boris E. Shmukler, Alan K. Stuart-Tilley, Lianwei Jiang, and Seth L. Alper. AE anion exchangers in atrial tumor cells. Am J Physiol Heart Circ Physiol 280: H937-H945, 2001.--Intracellular pH homeostasis and intracellular [Cl.sup.-] concentration in cardiac myocytes are regulated by anion exchange mechanisms. In physiological extracellular [Cl.sup.-] concentrations, [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] exchange promotes intracellular acidification and [Cl.sup.-] loading sensitive to inhibition by stilbene disulfonates. We investigated the expression of AE anion exchangers in the AT-1 mouse atrial tumor cell line. Cultured AT-1 cells exhibited a substantial basal [Na.sup.+]-independent [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (but not [Cl.sup.-]/ [OH.sup.-]) exchange activity that was inhibited by DIDS but not by dibenzamidostilbene disulfonic acid (DBDS). AT-1 cell [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] activity was stimulated two- to threefold by extracellular ATP and ANG II. AE mRNAs detected by RT-PCR in AT-1 cells included brain AE3 (bAE3), cardiac AE3 (cAE3), AE2a, AE2b, AE2c1, AE2c2, and erythroid AE1 (eAE1), but not kidney AE1 (kAE1). Cultured AT-1 cells expressed AE2, cAE3, and bAE3 polypeptides, which were detected by immunoblot and immunocytochemistry. An AE1-like epitope was detected by immunocytochemistry but not by immunoblot. Both bAE3 and cAE3 were present in intact AT-1 tumors. Cultured AT-1 cells provide a useful system for the study of mediators and regulators of [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] exchange activity in an atrial cell type. AT-1; band 3; AE1; AE3; chloride-bicarbonate exchange; atrium; heart