Editing Reversal potential (section)

==Use in research==
When V<sub>m</sub> is at the reversal potential for an event such as a synaptic potential ({{math|''V''<sub>m</sub> − ''E''<sub>rev</sub>}} is equal to 0), the identity of the ions that flow during an EPC can be deduced by comparing the reversal potential of the EPC to the equilibrium potential for various ions. For instance several excitatory [[ionotropic]] ligand-gated [[neurotransmitter]] [[Receptor (biochemistry)|receptors]] including [[glutamate receptor]]s ([[AMPA]], [[NMDA]], and [[kainate]]), [[nicotinic]] [[acetylcholine]] (nACh), and [[serotonin]] (5-HT<sub>3</sub>) receptors are nonselective cation channels that pass Na<sup>+</sup> and K<sup>+</sup> in nearly equal proportions, giving the reversal potential close to zero. The inhibitory ionotropic ligand-gated neurotransmitter receptors that carry [[chloride|Cl<sup>−</sup>]], such as [[GABA]]<sub>A</sub> and [[glycine]] receptors, have reversal potentials close to the resting potential (approximately −70 mV) in neurons.<ref name="Purves" />

This line of reasoning led to the development of experiments (by Akira Takeuchi and Noriko Takeuchi in 1960) that demonstrated that acetylcholine-activated ion channels are approximately equally permeable to Na<sup>+</sup> and K<sup>+</sup> ions. The experiment was performed by lowering the external Na<sup>+</sup> concentration, which lowers (makes more negative) the Na<sup>+</sup> equilibrium potential and produces a negative shift in reversal potential. Conversely, increasing the external K<sup>+</sup> concentration raises (makes more positive) the K<sup>+</sup> equilibrium potential and produces a positive shift in reversal potential.<ref name="Purves" />  A general expression for reversal potential of synaptic events, including for decreases in conductance, has been derived.<ref>{{cite journal | vauthors = Brown JE, Muller KJ, Murray G | title = Reversal potential for an electrophysiological event generated by conductance changes: mathematical analysis | journal = Science | volume = 174 | issue = 4006 | pages = 318 | date = October 14, 1971 | pmid = 5119107 | doi = 10.1126/science.174.4006.318 | bibcode = 1971Sci...174..318B | s2cid = 34404730 }}</ref>