title: [Electrophysiology principles of Na(+)/HCO3(-) cotransporters].
abstract: Ion channels and transporters represent two major types of pathways of transmembrane transport for ions. Distinct from ion channels which conduct passive ionic diffusion, ion transporters mediate active transport of ions. In the perspective of biochemistry, ion transporters are enzymes that catalyze the movement of ions across the plasma membrane. In the present review, we selected the Na(+)/HCO3(-) cotransporter (NBC) as an example to analyze the key biochemical and biophysical properties of ion transporters, including stoichiometry, turnover number and transport capacity. Moreover, we provided an analysis of the electrophysiological principles of NBC based on the laws of thermodynamics. Based on the thermodynamical analysis, we showed how the stoichiometry of an NBC determines the direction of its ion transport. Finally, we reviewed the methodology for experimental determination of the stoichiometry of NBC, as well as the physiological significance of the stoichiometry of NBCs in specific tissues.
authors.affiliation: Department of Biophysics and Molecular Physiology, Key Laboratory of Molecular Biophysics of Ministry of Education, Huazhong University of Science and Technology School of Life Science and Technology, Wuhan 430074, China.
authors.forename: Li-Ming
authors.initials: LM
authors.lastname: Chen
authors.affiliation: Department of Biophysics and Molecular Physiology, Key Laboratory of Molecular Biophysics of Ministry of Education, Huazhong University of Science and Technology School of Life Science and Technology, Wuhan 430074, China.
authors.forename: Mei
authors.initials: M
authors.lastname: Liu
authors.affiliation: Department of Biophysics and Molecular Physiology, Key Laboratory of Molecular Biophysics of Ministry of Education, Huazhong University of Science and Technology School of Life Science and Technology, Wuhan 430074, China. liuying@hust.edu.cn.
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
mesh_terms: D055724:Electrophysiological Phenomena; D017136:Ion Transport; D027982:Sodium-Bicarbonate Symporters
chemical_list: D027982:Sodium-Bicarbonate Symporters