Voltage-activated potassium currents in the somatic membrane of sensory neurons of early postnatal rats |
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Authors: | D A Vasilyev N S Veselovsky S A Fedulova |
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Institution: | (1) Bogomolets Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine |
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Abstract: | Transmembrane ion currents were studied in the somatic membrane of freshly isolated neurons from the spinal ganglia of early
postnatal (younger than 15-day-old) rats. According to their dissimilar voltage dependence and different sensitivity to external
application of tetraethylammonium (TEA) and 4-aminopyridine (4-AP), three types of outward potassium currents were identified.
Fast-inactivating K+ current was activated at the most negative values of the membrane potential and showed the highest sensitivity to external
application of 4-AP. The threshold for activation of slow-inactivating K+ current was within a −40 ... −30 mV range. Non-inactivating delay-rectified current showed the highest sensitivity to TEA.
All three types of K+ currents could be found in all studied neurons of animals of three age groups: 1, 5 to 6, and 14 to 15 postnatal days. The
mean density of fast-inactivating K+ current significantly increased during the first two weeks of postnatal ontogenesis. Within the studied period, the mode
of a normal (Gaussian) distribution of fast K+ current shifted toward higher current density values. The mean density of slow-inactivating K+ current also increased with the age. Yet, the mean density of non-inactivating delay-rectified K+ current significantly dropped during the first five days of the postnatal development and remained stable during the following
time interval. |
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