Korean J Orthod.  2000 Apr;30(2):197-204.

Properties of stretch-activated K+ channels in an G292 osteoblast-like cell

Affiliations
  • 1Department of Orthodontics, College of Dentistry, Pusan National University, Korea.
  • 2Department of Physiology, College of Medicine, Dong-A University, Korea.

Abstract

K+ -selective ion channels were studied in excised inside-out membrane patches from human osteoblast-like cells(G292). There classes of K+ channels were present and could be distinguished on the basis of conductance. Conductances were 270+/-27 pS, 113+/-12 pS, 48+/-8 pS according to their approximate conductances in symmetrical 140 mM KCI saline at holding potential of -80 mV. It was found that the small conductance (48 pS) K+ channel activation was dependent on membrane voltage. In current-voltage relationship, small conductance K+ channel showed outward rectification, and it was activated by the positive potential inside the membrane. In recordings, single channel currents were activayed by a negative pressure outside the membrane. The membrane pressure increased P(open) of the K+ channel in a pressure-dependent manner. In the excised-patch clamp recordings, G292 osteoblast-like cells have been shown to contain three types of K+ channels. Only the small conductance (48 pS) K+ channel is sensitive to the membrane stretch. These findings suggest that a hyperpolarzing current, mediated in part by this channel, may be associated with early events during the mechanical loading of the osteoblast. In G292 osteoblast-like cells, K+ channel is sensitive to membrane tension, and may represent a unique adaptation of the bone cell membrane to mechanical stress.

Keyword

G292 osteoblast-like cell; Stretch-activated K; channel

MeSH Terms

Cell Membrane
Humans
Ion Channels
Membranes
Osteoblasts
Stress, Mechanical
Ion Channels
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