Summary
Ionic currents in cultured dorsal root ganglion (DRG) neurons fromadult guinea pigs were analyzed by voltage-clamp techniques. The Na+ inward current had a reversal potential at +33mV, and revealed activation and inactivation kinetics similar to those of squid giant axons. A typical value for the maximum Na+ conductance was 178 mS/cm2 and the peak current was 2.5mA/cm2. The delayed K+ outward current showed a fast and a slow phase of inactivation and was sensitive to tetraethylammonium (TEA; ∼130mm) and 4-aminopyridine (∼2mm). The maximum K+ conductance was 26±9 (mean±sd) mS/cm2. The slow Ca2+ inward current was identified in Na+-free, TEA-containing solution. Its peak value was increased by 1.7-fold when [Ca2+]o was increased from 5 to 10mm. The current was blocked by Co2+ but not by tetrodotoxin. Sr2+ and Ba2+ could substitute in carrying this current. The maximum peak of the Ca2+ current was 0.22±0.14mA/cm2. At potentials positive to 0mV, the Ca2+ current was often followed by a slowly developing outward current, which was also sensitive to Co2+, suggesting a Ca2+-activated outward current. It is concluded that the action potential of theadult guinea pig DRG neuron is mediated by Ca2+ as well as by Na+ and K+ currents. The current densities of these ionic channels are considered to be different fromembryonic neurons and from nodes of Ranvier.
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Kameyama, M. Ionic currents in cultured dorsal root ganglion cells from adult guinea pigs. J. Membrain Biol. 72, 195–203 (1983). https://doi.org/10.1007/BF01870586
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DOI: https://doi.org/10.1007/BF01870586