Calcium in phase control of the Bulla circadian pacemaker.
Calcium in phase control of the Bulla circadian pacemaker.
复制标题
Bulla 昼夜节律起搏器相位控制中的钙。
DOI：
10.1016/0006-8993(90)91196-n
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发表时间：
1990
期刊：
影响因子：
2.9
通讯作者：
Block,GD
中科院分区：
文献类型：
--
作者：
Khalsa,SB;Block,GD
用离体全眼标本研究了海蜗牛Bulla gouldiana眼视网膜的昼夜节律起搏点。相位响应曲线产生6小时脉冲的低钙EGTA溶液和超极化低钾低钠溶液。两种治疗产生了相似的相位响应曲线，在主观夜间/主观白天早期出现相位延迟，在主观白天晚期出现相位提前。超极化和低钙溶液的相位响应曲线的相似性以及两种治疗组合时不存在加和性，这提高了两种治疗通过共同机制影响潜在起搏器的可能性。在去偏振光的存在下传递的低钙脉冲的相移的持久性表明，超极化对于低钙相移是不需要的。然而，这两种治疗都可能通过减少跨膜钙通量起作用，这被认为是由主观日期间起搏细胞膜的周期性去极化引起的。由于跨膜钙通量是必不可少的光和去极化诱导的相移，我们讨论的假设，钙通量的夹带途径的昼夜节律起搏器中发挥了关键作用。
The circadian pacemaker in the retina of the eye of the marine snailBulla gouldianawas examined using the whole eye in vitro preparation. Phase-response curves were generated to 6-h pulses of a low calcium EGTA solution and to a hyperpolarizing low potassium-low sodium solution. Both treatments yielded similar phase response curves with phase delays in the late subjective night/early subjective day and phase advances in the late subjective day. The similarity of the phase response curves to hyperpolarizing and low calcium solutions and the absence of additivity when both treatments are combined raises the possibility that both treatments affect the underlying pacemaker through a common mechanism. The persistence of phase shifts to low calcium pulses delivered in the presence of depolarizing light suggests that hyperpolarization is not required for low calcium phase shifting. However, it is possible that both treatments act by reducing a transmembrane calcium flux which is postulated to result from the periodic depolarization of the pacemaker cell membrane during the subjective day. Since a transmembrane calcium flux is known to be essential for both light and depolarization-induced phase shifting, we discuss the hypothesis that calcium fluxes play a pivotal role in the entrainment pathway of the circadian pacemaker.