Electrophysiological Characteristics of Hyperpolarization activated Current and Its Distribution in DRG Neurons
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Electrophysiological Characteristics of Hyperpolarization activated Current and Its Distribution in DRG Neurons
Acupuncture ResearchIssue 3, Pages: 229-230(2001)
作者机构:
北京大学神经科学研究所,北京,100083
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Published:2001
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Electrophysiological Characteristics of Hyperpolarization activated Current and Its Distribution in DRG Neurons[J]. Acupuncture research, 2001, (3): 229-230.
DOI:
Electrophysiological Characteristics of Hyperpolarization activated Current and Its Distribution in DRG Neurons[J]. Acupuncture research, 2001, (3): 229-230.DOI:
Electrophysiological Characteristics of Hyperpolarization activated Current and Its Distribution in DRG Neurons
摘要
The electrophysiological characters of hyerpolarization activated current (Ih) and its distribution in the cell bodies of rat dorsal root ganglion (DRG) neuron s with different diameters were studied by whole cell voltage and current cla mp methods. DRG neurons were classified into three group: small (diameter<30 μm )
median (30 μm ≤ d ≤ 40 μm ) and large (>40 μm) types. Ih was found as a slowly activating inward current evoked by hyperpolarizing voltage steps from a holding potential of -60 mV
and reversed at -32.34±2.56 mV(n=4). Ih could be specifically blocked by 2.0 mM Cs 2+ but not 1.0 mM Ba 2+
furthermore
100 μM cAMP applied into pipette solution could shift the activa tion curve to positive di rection (-91.4 mV vs -100.6 mV in control). Ih was observed in 11 of 49 small
17 of 22 median and 7 of 7 large diameter DRG neurons tested. The Density of Ih current in median and large cells was significantly higher than those in small o nes (11.88±1.59 pA/pF
5.05±0.39 pA/pF and 2.59±0.20 pA/pF
respectively). Ac tion potential at half amplitude (APD 1/2 ) varied in different types of DR G neurons. It was shown that large diameter cells had the shortest APD 1/2 than the other two types. These data suggested that Ih was mainly distributed in large and median diameter DRG neurons. Because some of Ih expressed neurons a re nociceptors
so it suggests that Ih may play a role in chronic pain.