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首页> 外文期刊>Journal of Neurophysiology >Evidence for a contribution of ICa to serotonergic modulation of IK,Ca in Hermissenda photoreceptors.
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Evidence for a contribution of ICa to serotonergic modulation of IK,Ca in Hermissenda photoreceptors.

机译：在Hermissenda感光细胞中ICa对IK，Ca的血清素能调节的贡献的证据。

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1. The Ca(2+)-dependent K+ current (IK,Ca) contributes to both the plateau phase of light-elicited generator potentials and enhanced excitability of identified type B photoreceptors of Hermissenda detected after classical conditioning. Serotonergic modulation of membrane conductances mimics some of the effects of conditioning. Serotonin (5-HT) reduces the magnitude of IK,Ca and decreases the sustained voltage-activated Ca2+ current (ICa) in type B photoreceptors. We have examined the modulatory role of 5-HT in regulation of IK,Ca by ICa using a Ca2+ ionophore in conjunction with the whole cell patch-clamp technique in isolated photoreceptors. 2. The 40-50% reduction of IK,Ca by 5-HT was voltage independent. Cd2+ blocked ICa and reduced IK,Ca by 70-80%. The remaining 20-30% of IK,Ca may result from Ca2+ release from intracellular stores, because IK,Ca was further reduced to 5-10% as the pipette ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) was raised from 0.5 to 5 mM. The application of the Ca2+ ionophore A23187, which was designed to produce Ca2+ influx independent of the voltage-activated Ca2+ channels, restored IK,Ca. 3. The application of A23187 reversed the effects of 5-HT and Cd2+ on IK,Ca for experiments lasting 15-20 min. However, for longer time periods (> 25 min), complete restoration of IK,Ca by A23187 was obtained in the presence of Cd2+ but not 5-HT. These results suggest that for 15 to 20 min exposures the reduction of IK,Ca by 5-HT is a consequence of modulation of ICa by 5-HT and not a direct effect of 5-HT on IK,Ca.
机译：1.依赖Ca（2+）的K +电流（IK，Ca）有助于光激发的发电机电位的平稳期和经典条件下检测到的Hermissenda B型感光体的兴奋性增强。膜电导的血清素能调节模拟了调节的某些作用。 5-羟色胺（5-HT）降低IK，Ca的幅度并降低B型感光体的持续电压激活的Ca2 +电流（ICa）。我们已经研究了5-HT在通过使用钙离子载体结合全细胞膜片钳技术在孤立的感光细胞中通过ICa调控IK，Ca的调节作用。 2. 5-HT将IK，Ca降低40-50％与电压无关。 Cd2 +阻断了ICa，并将IK，Ca降低了70-80％。 IK，Ca的剩余20-30％可能是由于细胞内存储释放Ca2 +所致，因为随着移液器乙二醇-双（β-氨基乙基醚）-N，N，N的影响，IK，Ca进一步降低至5-10％ '，N'-四乙酸（EGTA）从0.5mM增加到5mM。 Ca2 +离子载体A23187的应用旨在恢复独立的IK，Ca，Ca23 +离子载体可独立于电压激活的Ca2 +通道产生Ca2 +流入。 3. A23187的应用逆转了5-HT和Cd2 +对IK，Ca持续15-20分钟的实验的影响。但是，对于较长的时间段（> 25分钟），在Cd2 +而不是5-HT存在下，通过A23187可以完全还原IK，Ca。这些结果表明，在15至20分钟的暴露时间内，5-HT降低IK，Ca是5-HT调节ICa的结果，而不是5-HT对IK，Ca的直接影响。

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