A Ca2+ channel in renal epithelial cells introduced by parathyroid hormone.
To investigate the mechanism of Ca2+ influx after hormonal stimuli, patch clamping with [Ca2+]i fluorescence measurement was performed in single renal proximal epithelial cells. A Ca2+ current appeared along with a rise in [Ca2+]i during parathyroid hormone addition to the bath, but not when the hormone was inside the cell-attached pipette. The Ca2+ channel, possessing linear I-V, was nonselective for cations, most active in hyperpolarized--membranes and showed oscillatory fluctuations in opening, which disappeared after excision. GTP gamma S opened the channel that had disappeared, which was suppressed by GDP beta S. These data show a PTH-responsive Ca2+ channel for which GTP/GDP may act as second messenger to open the latent Ca2+ channel.
Suzuki
M
M
Department of Pharmacology, Jichi Medical University, Tochigi, Japan.
Taniguchi
J
J
D015220:Calcium Channels / Q000187:drug effects*; D002463:Cell Membrane Permeability / Q000187:drug effects*; D002478:Cells, Cultured; D004847:Epithelial Cells; D004848:Epithelium / Q000187:drug effects; D005456:Fluorescent Dyes; D016257:Fura-2 / Q000031:analogs & derivatives; D007668:Kidney / Q000166:cytology / Q000187:drug effects*; D010281:Parathyroid Hormone / Q000494:pharmacology*; D018408:Patch-Clamp Techniques
D015220:Calcium Channels; D005456:Fluorescent Dyes; D010281:Parathyroid Hormone; C049925:fura-2-am; D016257:Fura-2