Inhibitors of membrane transport system for organic anions block fura-2 excretion from PC12 and N2A cells
- 15 December 1988
- journal article
- Published by Portland Press Ltd. in Biochemical Journal
- Vol. 256 (3), 959-963
- https://doi.org/10.1042/bj2560959
Abstract
The neuroblastoma-like cell line N2A and the pheochromocytoma-like cell line PC12 excrete about 20-25% of the intracellular fluorescent Ca2+ indicator fura-2 during 10 min of incubation at 37 degrees C. The drug probenecid, known to inhibit membrane systems for the transport of organic anions [Cunningham, Israili & Dayton (1981) Clin. Pharmacol. 6, 135-151], inhibited fura-2 excretion in both cell types. However, probenecid also had untoward effects on intracellular Ca2+ homeostasis in N2A and PC12 cells. We therefore tested the drug sulphinpyrazone, another known inhibitor of organic-anion transport systems. Sulphinpyrazone fully inhibited excretion of fura-2 at 250 microM, a concentration one order of magnitude lower than that of probenecid. At this concentration and for incubation times up to 20 min, sulphinpyrazone had no untoward effects on cell viability and metabolic functions. Fura-2 was also loaded into the cytoplasm of N2A cells by permeabilization of the plasma membrane with extracellular ATP. In this case as well, the dye was rapidly released from the cells and the efflux was blocked by sulphinpyrazone. These findings suggest that N2A and PC12 cells possess a membrane system for the transport of the free-acid form of fura-2. This transport system is probably responsible for the excretion of fura-2 from these cells. Incubation of N2A and PC12 cells with sulphinpyrazone may help overcome problems arising in the investigation of [Ca2+]i homeostasis in these cell types.Keywords
This publication has 13 references indexed in Scilit:
- Fc receptor-mediated phagocytosis occurs in macrophages at exceedingly low cytosolic Ca2+ levels.The Journal of cell biology, 1988
- Calcium and inositolphosphates in the activation of T cell-mediated cytotoxicity.The Journal of Experimental Medicine, 1987
- Voltage-dependent activation and inactivation of calcium channels in PC12 cells. Correlation with neurotransmitter release.Journal of Biological Chemistry, 1987
- ATP4- permeabilizes the plasma membrane of mouse macrophages to fluorescent dyes.Journal of Biological Chemistry, 1987
- Calcium gradients in single smooth muscle cells revealed by the digital imaging microscope using Fura-2Nature, 1985
- The Ca signal from fura‐2 loaded mast cells depends strongly on the method of dye‐loadingFEBS Letters, 1985
- Cytosolic Ca2+ homeostasis in Ehrlich and Yoshida carcinomas. A new, membrane-permeant chelator of heavy metals reveals that these ascites tumor cell lines have normal cytosolic free Ca2+.Journal of Biological Chemistry, 1985
- A new generation of Ca2+ indicators with greatly improved fluorescence properties.Journal of Biological Chemistry, 1985
- Cyclic AMP inhibition of fMet-Leu-Phe-dependent metabolic responses in human neutrophils is not due to its effects on cytosolic Ca2+Biochemical Journal, 1984
- Clinical Pharmacokinetics of ProbenecidClinical Pharmacokinetics, 1981