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- Title
Calcium release from intracellular stores evoked by extracellular ATP in a X enopus renal epithelial cell line.
- Authors
Mori, Masahiro; Hosomi, Hidenobu; Nishizaki, Tomoyuki; Kawahara, Katsumasa; Okada, Yasuhiro
- Abstract
The signal transduction mechanism mediating extracellular adenosine 5′-triphosphate (ATP)-induced calcium release in a renal epithelial cell line (A6) was investigated using the whole-cell voltage-clamp technique and fura-2 fluorescence measurement., ATP (10 μ M) activated calcium-dependent non-selective cation channels in cells held under voltage clamp., Guanosine 5′- O-(2-thiodiphosphate) (GDPβS; 0.1-1.0 m M) in the pipette inhibited the ATP-activated calcium-dependent currents. With guanosine 5′- O-(3-thiotriphosphate) (GTPγS; 0.1-1.0 m M) in the pipette, the currents were spontaneously elicited without application of ATP. Pretreatment with pertussis toxin (PTX) affected neither the ATP-activated currents nor the increase in intracellular free calcium concentration ([Ca 2+])i evoked by ATP., Intracellular application of neomycin or heparin inhibited the ATP-activated currents. Inositol 1,4,5-trisphosphate (IP3; 0.1-100μ M) in the internal solution produced currents similar to those due to ATP activation., These results suggest that a PTX -insensitive guanosine 5′-triphosphate (GTP)-binding regulatory protein (G protein) is involved in extracellular ATP-induced phosphoinositide turnover and subsequent calcium release from IP3 -sensitive stores, which subsequently activates the calcium -dependent channels in A6 cells.
- Publication
Journal of Physiology, 1997, Vol 502, Issue 2, p365
- ISSN
0022-3751
- Publication type
Article
- DOI
10.1111/j.1469-7793.1997.365bk.x