Patch-Clamp Analysis of Membrane Transport in Erythrocytes

Among all the models used to study membrane transport, erythrocytes (Red Blood Cells, RBCs) have probably been the most utilised cell type. Radioisotopes fluxes, isosmotic haemolysis, ion content analysis (e.g. flame photometry), or fluorescence techniques have been widely used to characterise the various transporters present in the RBCs membrane. These techniques have allowed the description of several types of transporters such as pumps, specific solute transporters, symporters or antiporters, and even ion channels. However, the physiology of RBCs and their maintenance of homeostasis remains incompletely understood, and electrophysiology has proven, since the first single-channel recording on a human erythrocyte membrane thirty years ago, to be a very useful tool to understand more deeply RBC membrane transport. Why does one use these techniques on a small, non-excitable cell that has long been considered no more than an empty bag of haemoglobin? The diversity of transporters in the RBC membrane, including ion channels, shows that these cells are much more complex than expected. Indeed, ion channels now described in the RBC membrane (from Mammals to other Vertebrates) are implicated in important phenomena and functions throughout the cells lifespan (gas transports, cell volume regulation, differentiation and death). In this chapter, we will describe the main properties of the erythrocyte’s membrane transport system, how electrophysiological techniques can be applied, and how they have contributed to the comprehension of erythrocyte physiology with the description of the various ion channels that can be found in RBC membrane.