Properties of stretch-activated K+ channels in an G292 osteoblast-like cell.
- Author:
Sang Gook LEE
1
;
Soo Byung PARK
;
Dong Keun JUNG
;
Duk Joon SUH
Author Information
1. Department of Orthodontics, College of Dentistry, Pusan National University, Korea.
- Publication Type:Original Article
- Keywords:
G292 osteoblast-like cell;
Stretch-activated K;
channel
- MeSH:
Cell Membrane;
Humans;
Ion Channels;
Membranes;
Osteoblasts;
Stress, Mechanical
- From:Korean Journal of Orthodontics
2000;30(2):197-204
- CountryRepublic of Korea
- Language:Korean
-
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.
