The resting membrane potential of Drosophila melanogaster larval muscle depends strongly on external calcium concentration.
The resting membrane potential of Drosophila melanogaster larval muscle depends strongly on external calcium concentration.
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DOI：
10.1016/j.jinsphys.2009.11.002
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发表时间：
2010-03
影响因子：
2.2
通讯作者：
J. Krans;K. Parfitt;Kristin D Gawera;P. Rivlin;R. Hoy
中科院分区：
文献类型：
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作者：
J. Krans;K. Parfitt;Kristin D Gawera;P. Rivlin;R. Hoy
大多数细胞的静息膜电位 (RMP) 不受跨膜钙梯度的影响很大，因为在静息状态下，膜对钙的渗透性非常低。然而，我们观察到，随着外部钙浓度的改变，果蝇幼虫体壁中肌肉细胞的静息膜电位变化很大。 RMP 在低浓度下使钙离子去极化高达 21.8mV/mM，在神经生理学研究的典型范围内平均约 10mV/mM。肌肉 RMP 变化的程度对于突触电位的测量也有重要影响。在一系列 RMP 中比较了兴奋性连接电位 (EJP) 电压的两个参数。 EJP 幅度 (ΔV) 和峰值电压（最大值）随 RMP 变化而变化；平均而言，RMP 变化 10mV 会引起 EJP 幅度和峰值电压变化 4-5mV。钙梯度对静息和突触膜电位的影响促使我们研究幼虫血淋巴的内源离子浓度。除了主要的单价离子和钙之外，我们还首次对幼虫果蝇血淋巴中的镁浓度进行了伏安分析。
The resting membrane potential (RMP) of most cells is not greatly influenced by the transmembrane calcium gradient because at rest, the membrane has very low permeability to calcium. We have observed, however, that the resting membrane potential of muscle cells in the larval bodywall of Drosophila melanogaster varies widely as the external calcium concentration is modified. The RMP depolarized as much as 21.8mV/mM calcium at low concentrations, and on average, about 10mV/mM across a range typical of neurophysiological investigations. The extent to which muscle RMP varies has important implications for the measurement of synaptic potentials as well. Two parameters of excitatory junctional potential (EJP) voltage were compared across a range of RMPs. EJP amplitude (ΔV) and peak voltage (maxima) change as a function of RMP; on average, a 10mV change in RMP elicits a 4–5mV change in EJP amplitude and peak voltage. The influence of the calcium gradient on resting and synaptic membrane potentials led us to investigate the endogenous ion concentrations of larval hemolymph. In addition to the major monovalent ions and calcium, we report the first voltammetric analysis of magnesium concentration in larval fruit fly hemolymph.