2006 Fiscal Year Final Research Report Summary
Identification of osmo-sensitive K channel in the ciliary epithelial cells and its regulation of aqueous humor formation.
| Project/Area Number |
16591742
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Ophthalmology
|
|---|
| Research Institution | Kanazawa University |
|---|
Principal Investigator |
TAKAHIRA Masayuki Kanazawa University, Ophthalmology, Assistant Professor, 医学部附属病院, 講師 (70283108)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
SAKURAI Mayuki Kanazawa University, Ophthalmology, Assistant Professor, 医学系研究科, 助手 (50303269)
|
|---|
| Project Period (FY) |
2004 – 2006
|
| Keywords | ciliary epithelium / K channel / KCNQ / patch clamp / muscarin / camp / aqueous humor formation |
|---|
| Research Abstract |
Chloride transport across the ciliary epithelium plays a critical role in aqueous humor formation. In other secretary epithelia, K+ recycling through K+ channels is crucial for the transepithelial transport of chloride, but the specific K+ channels that serve this function in the ciliary epithelium have not been elucidated. The purpose of this study was to investigate the electrophysiological and pharmacological properties of K+ channels in the pigmented ciliary epithelium (PE). Porcine ciliary epithelial cells were freshly dissociated using papain and perfused with HEPES-buffered Ringer solution. Whole-cell currents were recorded using the perforated-patch configuration of the patch-clamp technique from pairs of PE and nonpigmented ciliary epithelial (NPE) cells, or single PE cells. PE-NPE cell pairs had a zero-current potential averaging・8 mV (n = 79) and exhibited a prominent outward K+ current. This current activated slowly at voltages positive to approximately・0 mV (V_<1/2>=-63 mV, n=12) and did not inactivate during prolonged depolarization. An identical K+ current was also observed in isolated PE cells (n=11). The IC_50 for current block by the classical K+ channel inhibitor tetraethylammonium (TEA) was >20 mM. Exposure to hypo-osmotic solution (210 mosm) markedly augmented this K+ current. These features suggest that the K channel is KCNQ5. This channel may recycle K+ in the pigmented ciliary epithelium and thereby regulate the transepithelial transport of chloride.
|
