Measurement of the cytosolic sodium ion concentration in rat brain synaptosomes by a fluorescence method |
| |
Authors: | Sathapana Kongsamut Daniel A. Nachshen |
| |
Abstract: | A method for the measurement of the cytosolic Na+ concentration in intact synaptosomes is described. This method makes use of a pH sensitive dye (BCECF) that can be loaded into the cytosol and a relatively specific ionophore (monensin) that can exchange Na+ for H+ across the synaptosomal membrane. By setting conditions such that there is no electrochemical potential difference for H+ across the membrane (no membrane potential and pHi = pHo), addition of ionophore would induce a H+ flux only if there is a concentration difference for Na+. Thus, when there is no fluorescence change (no cytosolic pH change) extracellular [Na+] equals intrasynaptosomal [Na+. The intrasynaptosomal [Na+] concentration was determined to be 7 ± 3 mM (n = 5; mean ± S.E.). The results obtained with this fluorescence method are compared with estimates obtained by atomic absorption spectrometry. Limitations and applications of the method are discussed. |
| |
Keywords: | Sodium ion, intracellular Calcium ion, intracellular Fluorescence pH Ionophore |
本文献已被 ScienceDirect 等数据库收录! |