Control of the light-regulated current in rod photoreceptors by cyclic GMP, calcium, and l-cis-diltiazem.
Control of the light-regulated current in rod photoreceptors by cyclic GMP, calcium, and l-cis-diltiazem.
复制标题
通过环 GMP、钙和 L-顺式地尔硫卓控制视杆光感受器中的光调节电流。
DOI：
10.1073/pnas.83.4.1163
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发表时间：
1986
影响因子：
11.1
通讯作者：
MacLeish,PR
中科院分区：
文献类型：
--
作者：
Stern,JH;Kaupp,UB;MacLeish,PR
用离体膜片技术观察钙离子对外节膜cGMP激活电流的影响。细胞外钙离子浓度的变化对cGMP激活电流有显著影响，而细胞内钙离子浓度的变化对cGMP激活电流无明显影响。在没有cGMP的情况下，钙离子浓度的变化对膜电导几乎没有影响。这些结果表明，胞内cGMP和胞外钙都可以直接影响视杆细胞光反应的电导。药理药剂L-顺式-地尔硫卓应用于切除的贴片细胞内侧时，可逆地抑制cGMP激活的电流。当超融合在完整的视杆细胞上时，L-顺式-地尔硫卓可逆地阻断了大部分正常的光反应。D-顺式地尔硫卓的异构体对斑块或完整的杆状细胞都没有显著影响。因此，光调控的电导具有钙和cGMP的结合部位，可能在杆状细胞的正常光反应过程中相互作用，以及L-顺式-地尔硫卓的特异结合部位，可用于鉴定和进一步研究电导机制。
The effect of calcium ions on the cGMP-activated current of outer segment membrane was examined by the excised-patch technique. Changes in the extracellular calcium concentration had marked effects on the cGMP-activated current, while changes in intracellular calcium concentration were ineffective. Changes in calcium concentration in the absence of cGMP had little, if any, effect on membrane conductance. These results suggest that both intracellular cGMP and extracellular calcium can directly affect the conductance underlying the light response in rod cells. The pharmacological agent l-cis-diltiazem reversibly inhibited the cGMP-activated current when applied to the intracellular side of an excised patch. When superfused over intact rod cells, l-cis-diltiazem reversibly blocked much of the normal light response. The isomer, d-cis-diltiazem, did not significantly affect either patches or intact rod cells. Thus, the light-regulated conductance has binding sites for both calcium and cGMP that may interact during the normal light response in rod cells and a site specific for l-cis-diltiazem that can be used to identify and further study the conductance mechanism.