Endogenous polyamines modulate Ca2+ channel activity in guinea-pig intestinal smooth muscle
Endogenous polyamines modulate Ca2+ channel activity in guinea-pig intestinal smooth muscle
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DOI：
10.1007/s004240051060
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发表时间：
1999-09-01
影响因子：
4.5
通讯作者：
Hellstrand, P
中科院分区：
文献类型：
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作者：
Gomez, M;Hellstrand, P
多胺、精胺和亚精胺对豚鼠回肠细胞全细胞记录的L钙通道有抑制作用(Gomez和Hellstrand，Pflugers Arch，430：501-507,1995[4])。为了研究它们是否在生理条件下调节通道活动，我们进一步研究了它们对钙通道的作用以及细胞内多胺含量变化的影响。在由内向外的斑块中，精胺(0.1-1 mM)抑制通道活动，但不影响单位电流的幅度。在细胞贴附记录中，将精胺加入到镀液中并不影响贴片中的通道活动，这表明其细胞外作用是直接的，而不是通过多胺通过细胞膜而介导的。用腺苷蛋氨酸脱羧酶抑制剂CGP48664(10 MU M)对回肠组织进行5d器官培养，细胞内精胺和亚精胺的含量降低了约50%。这导致了细胞附着记录中通道活性的增强，表明与对照细胞相比，内源性多胺对通道的阻断程度有所降低。穿孔贴片模式下的全细胞记录显示，在多胺耗竭的细胞中，电流增加，而当细胞用移液管溶液透析时，这是看不到的。我们的结论是，多胺既能阻断细胞膜内外的钙通道，也能阻断细胞膜内外的钙通道，而平滑肌中的内源性多胺对钙通道的活动有调节作用。
The polyamines spermine and spermidine inhibit L-type Ca2+ channels in whole-cell recordings from guinea-pig ileum cells (Gomez and Hellstrand, Pflugers Arch, 430:501-507, 1995 [4]). To study whether they modulate channel activity under physiological conditions, we further investigated their actions on Ca2+ channels and the effects of altered cellular polyamine contents. In inside-out patches, spermine (0.1-1 mM) inhibited channel activity without affecting the amplitude of unitary currents. In cell-attached recordings, addition of spermine to the bath did not influence channel activity in the patch, indicating that its extracellular action is direct and not mediated via passage of the polyamine through the cell membrane. Cellular contents of spermidine and spermine were decreased by about 50% by organ culture of ileum strips for 5 days with the adenosylmethionine decarboxylase inhibitor CGP 48664 (10 mu M). This caused enhanced channel activity in cell-attached recordings, suggesting a reduced level of channel block by endogenous polyamines compared with control cells. Whole-cell recordings in the perforated patch mode showed increased current in polyamine-depleted cells, while this was not seen when cells were dialysed with the pipette solution. We conclude that polyamines block Ca2+ channels from the inside as well as the outside of the cell membrane, and that endogenous polyamines in smooth muscle modulate Ca2+ channel activity.