title: Acute Hypoxia Activates an ENaC-like Channel in Rat Pheochromocytoma (PC12) Cells.
abstract: Cells can resist and even recover from stress induced by acute hypoxia, whereas chronic hypoxia often leads to irreversible damage and eventually death. Although little is known about the response(s) to acute hypoxia in neuronal cells, alterations in ion channel activity could be preferential. This study aimed to elucidate which channel type is involved in the response to acute hypoxia in rat pheochromocytomal (PC12) cells as a neuronal cell model. Using perfusing solution saturated with 95% N(2) and 5% CO(2), induction of cell hypoxia was confirmed based on increased intracellular Ca(2+) with diminished oxygen content in the perfusate. During acute hypoxia, one channel type with a conductance of about 30 pS (2.5 pA at -80 mV) was activated within the first 2~3 min following onset of hypoxia and was long-lived for more than 300 ms with high open probability (P(o), up to 0.8). This channel was permeable to Na(+) ions, but not to K(+), Ca(+), and Cl(-) ions, and was sensitively blocked by amiloride (200 nM). These characteristics and behaviors were quite similar to those of epithelial sodium channel (ENaC). RT-PCR and Western blot analyses confirmed that ENaC channel was endogenously expressed in PC12 cells. Taken together, a 30-pS ENaC-like channel was activated in response to acute hypoxia in PC12 cells. This is the first evidence of an acute hypoxia-activated Na(+) channel that can contribute to depolarization of the cell.
authors: Department of Physiology, Institute of Health Sciences and Medical Research Center for Neural Dysfunction, Gyeongsang National University School of Medicine, Jinju 660-751, Korea.
authors: Yeon Ju
authors: YJ
authors: Bae
authors: Jae-Cheal
authors: JC
authors: Yoo
authors: Nammi
authors: N
authors: Park
authors: Dawon
authors: D
authors: Kang
authors: Jaehee
authors: J
authors: Han
authors: Eunmi
authors: E
authors: Hwang
authors: Jae-Yong
authors: JY
authors: Park
authors: Seong-Geun
authors: SG
authors: Hong
keywords: Acute hypoxia; Amiloride; Epithelial Na channel; PC12 Cells; Rats