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KMID : 0811720050090000061
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Korean Journal of Physiology & Pharmacology
2005 Volume.9 No. 0 p.61 ~ p.0
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Requirement of Non-selective Cation Channels in Generating Spontaneous Firing and Basal Ca2+ Level in Midbrain Dopamine Neurons
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Kim Shin-Hye
Chung Sung-Kwon
Park Myoung-Kyu
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Abstract
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Midbrain dopamine neurons are known to generate spontaneous firing in vivo, in vitro, and even in isolated cells. It has been reported that voltage-operated Ca2+channels (VOCCs) play critical roles in generating spontaneous firing activities and cytosolic Ca2+ level and many types of VOCCs are expressed in dopamine neurons. Recently the canonical (or short) form of transient receptor potential channels (TRPC) are reported to be widely present in the midbrain dopamine neurons. However, their functional role is not clear in the dopamine neurons. Thus we have investigated how nonselective cation channels and VOCC contribute to generation or modulation of spontaneous firing in the acutely isolated midbrain dopamine neurons which were regularly firing by directly measuring spontaneous firing activity and cytosolic Ca2+ concentration([Ca2+]c). The spontaneous firing was slightly blocked by specific L-type Ca2+ channel (10μm nifedipine, 2μm nimodipine) and cocktail of the above VOCC (L-type, N-type (1μm ω-conotoxin GVIA), and P/Q-type (1μm ω- agatoxin) Ca2+ channel) antagonists. However, the spontaneous firing was completely inhibited by nonselective cation channel blockers, 20μm 2APB, 10μm SKF 96365, and 10μm La3+ while [Ca2+]c remained at the deceased level. In this study, we concluded that nonselective cation channels could play a key role in the regulation of spontaneous firing activity and basal Ca2+ level in the midbrain dopamine neurons.
Source: Korean Journal of Physiology & Pharmacology.2005 Oct;9(Suppl I):S85-S85
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KEYWORD
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Dopamine neuron, VOCC, Nonselective cation channel, Spontaneous firing, Substantia nigra
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