Multi-walled carbon nanotubes suppress potassium channel activities in PC12 cells.
The advancement in nanotechnology has produced technological and conceptual breakthroughs but the effects nanomaterials have on organisms at the cellular level are poorly understood. Here we report that carboxyl-terminated multi-walled carbon nanotubes (MWCNTs) act as antagonists of three types of potassium channels as assessed by whole-cell patch clamp electrophysiology on undifferentiated pheochromocytoma (PC12) cells. Our results showed that carboxyl-terminated MWCNTs suppress the current densities of I(to), I(K) and I(K1) in a time-dependent and irreversible manner. The suppressions were most distinct 24 h after incubation with MWCNTs. However, MWCNTs did not significantly change the expression levels of reactive oxygen species (ROS) or intracellular free calcium and also did not alter the mitochondrial membrane potential (DeltaPsi(m)) in PC12 cells. These results suggest that oxidative stress was not involved in the MWCNTs suppression of I(to), I(K) and I(K1) current densities. Nonetheless, the suppression of potassium currents by MWCNTs will impact on electrical signaling of excitable cells such as neurons and muscles.
Xu
Haifei
H
Department of Physiology and Pathophysiology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, PR China.
Bai
Juan
J
Meng
Jie
J
Hao
Wei
W
Xu
Haiyan
H
Cao
Ji-Min
JM
D000818:Animals; D002118:Calcium / Q000378:metabolism; D005434:Flow Cytometry; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D018613:Microscopy, Confocal; D037742:Nanotubes, Carbon / Q000009:adverse effects*; D018384:Oxidative Stress / Q000187:drug effects; D016716:PC12 Cells; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000378:metabolism*; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism
D037742:Nanotubes, Carbon; D015221:Potassium Channels; D017382:Reactive Oxygen Species; D002118:Calcium