External Mg2+ triggers oscillations and a subsequent sustained level of intracellular free Ca2+, correlated with changes in membrane conductance in the oocyte of the prawn Palaemon serratus
External Mg2+ triggers oscillations and a subsequent sustained level of intracellular free Ca2+, correlated with changes in membrane conductance in the oocyte of the prawn Palaemon serratus
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DOI：
10.1006/dbio.1996.0154
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发表时间：
1996-07-10
影响因子：
2.7
通讯作者：
Goudeau, H
中科院分区：
文献类型：
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作者：
Goudeau, M;Goudeau, H
我们使用荧光Ca 2+指示剂Ca绿色葡聚糖以及电压和电流钳方法提供了证据，证明外部Mg 2+在不需要受精的情况下诱导虾卵母细胞[Ca 2 +]（i）和膜电流或电位的相关变化。用标准（40 mM Mg 2+）ASW替代无Mg 2 + ASW触发了双相[Ca 2 +]（i）反应，包括振荡期，随后是无振荡的持续[Ca 2 +]（i）水平的第二状态，分别持续约70 min和长达3 h。相反，在无Mg 2 + ASW中长时间保存的卵母细胞的[Ca 2 +]（i）没有变化，其保持在约0.2 μ M的基础浓度。同时记录的[Ca ~（2+）]（i）和膜或电流的变化表明，振荡周期开始于第一个[Ca ~（2+）]（i）峰（约1.7 μ M），并与初始瞬时膜超极化或瞬时初始外向电流峰相关。第一个[Ca 2 +]（i）峰之后是[Ca 2 +]（i）的缓慢降低，随后是一系列[Ca 2 +]（i）瞬变，同时伴有膜的缓慢去极化或相关的内向电流。振荡周期结束时，[Ca 2 +]（i）（约0.6 μ M）的振荡平台持续49.6 +/- 4.5分钟，其开始是伴随着最终的膜超极化或相关的最终外向电流。外源Mg ~（2+）与卵母细胞膜之间的持续接触是维持[Ca ~（2+）]（i）程序和膜电导变化所必需的。Ca ~（2+）流动的来源是第一个峰和随后的一系列[Ca ~（2+）]（i）振荡的内部来源，而振荡平台和持续的[Ca ~（2+）]（i）水平的第二个状态主要是外部来源。皮层反应的第一步和第二步分别发生在振荡平台期和持续[Ca ~（2+）]（i）水平的第二状态。(C)出版社：Academic Press，Inc.
We have provided evidence that external Mg2+ induces correlated changes in [Ca2+](i) and membrane current or potential in prawn oocytes without any requirement of fertilization, using the fluorescent Ca2+ indicator Ca green dextran and voltage and current clamp methods. Replacement of Mg2+-free ASW with standard (40 mM Mg2+)ASW triggered a diphasic [Ca2+](i) response consisting of an oscillation period followed by a second state of sustained [Ca2+](i) level devoid of oscillation, lasting about 70 min and up to 3 hr, respectively. In contrast, oocytes maintained for a long time in Mg2+-free ASW showed no changes in [Ca2+](i) which remained at a basal concentration of about 0.2 mu M. The simultaneous records of [Ca2+](i) and membrane or current changes showed that the oscillation period started with a first [Ca2+](i) peak (about 1.7 mu M) and was correlated with an initial transient membrane hyperpolarization or a transient initial outward current peak. The first [Ca2+](i) peak was followed by a slow decrease in [Ca2+](i) followed by a series of [Ca2+](i) transients, concurrent with a slow depolarization of the membrane or a related inwardly directed current. The oscillation period ended with an oscillatory plateau of [Ca2+](i) (about 0.6 mu M) lasting 49.6 +/- 4.5 min, the onset of which was concomitant with a final membrane hyperpolarization or a related final outward current. A continuous contact between external Mg2+ and the oocyte membrane was necessary to maintain the program of [Ca2+](i) and membrane conductance changes. The sources of Ca2+ mobilization are of internal origin for both the first peak and the subsequent series of [Ca2+](i) oscillations, and are mainly of external origin for the oscillation plateau and for the second state of sustained [Ca2+](i) level. The first and second step of the cortical reaction occurred during the oscillatory plateau and the second state of sustained [Ca2+](i) level, respectively. (C) 1996 Academic Press, Inc.