Regulation of the CaィイD12+ィエD1 channels of rat osteoclast by the signals of bone resorption and formation

During bone resorption， osteoclasts are exposed to unusually high ambient CaイイD12+イエD1。This leManagement to Ca D12+ Ca D1 influx and Ca D12+ Ca D1 release from intracellular Ca D12+ Ca D1 stores， which result in a sharp cytosolic Ca D12+ Ca D1 increase。最后，细胞酸钙中的上升（D12+ D1）被转化为骨还原的抑制。It has been demonstrated that a ryanodine receptor （RyR） isoform， expressed in the osteoclast plasma·brane， functions as a CaイD12+イイD1 channel and a CaイD12+イイD1 sensor。这一假说是由cyiosolic Ca的测量所建议的。However， a pathway for the CaイイD12+イエD1 influx through the plasma·brane of osteoclast has not been identified electrophysiologically。在这个研究中，我们测量了一个当前的版本，它可以携带Ca-D12+-D1 in the inside-out patch clamp configuration。目前可以通过含有高浓度（0.1 mM）的ruthenium red （RtR）加上3 mM MgClii D22-D2的内部解决方案的应用来衡量，而当它被低浓度（10 μ M）的RtR阻塞时。目前的当量潜力接近+5 mV，电导率为20 pS （管盒溶液含有10 mM CaCly D22-D2）和27 pS（60 mM CaCly D22-D2），尊重。这些结果与RtR触发了细胞酸Ca D12+ D1浓度的报告一致（Adebanjo OA等人，Am J Physiol 270 ：F469-F475）。Here， we provided evidences using an electrophysiological method that RyR expressed in the plasma membrane of osteoclasts were able to conduct CaイイD12+イエD1ions for the first time。

During bone resorption, osteoclasts are exposed to unusually high ambient CaィイD12+ィエD1. This leads to CaィイD12+ィエD1 influx and CaィイD12+ィエD1 release from intracellular CaィイD12+ィエD1 stores, which result in a sharp cytosolic CaィイD12+ィエD1 increase. Finally, the rise in cytosolic CaィイD12+ィエD1 is transduced into an inhibition of bone resorption. It has been demonstrated that a ryanodine receptor (RyR) isoform, expressed in the osteoclast plasma membrane, functions as a CaィイD12+ィエD1 channel and a CaィイD12+ィエD1 sensor. This hypothesis was suggested by the measurement of cyiosolic CaィイD12+ィエD1 concentration. However, a pathway for the CaィイD12+ィエD1 influx through the plasma membrane of osteoclast has not been identified electrophysiologically. In this study, we measured a current that can carry CaィイD12+ィエD1 in the inside-out patch clamp configuration. The current could be measured by the application of the intracellular solution containing high concentration (0.1 mM) of ruthenium red (RtR) plus 3 mM MgClィイD22ィエD2, while it was blocked by low concentration (10 μ M) of RtR. The equilibrium potential of this current was approximately +5 mV, and the conductances were 20 pS (pipette solution contained 10 mM CaClィイD22ィエD2) and 27pS (60 mM CaClィイD22ィエD2), respectively. These results are consistent with the report that RtR triggered an elevation of cytosolic CaィイD12+ィエD1 concentration only when high concentration of RtR was applied (Adebanjo OA et al. Am J Physiol 270 : F469-F475). Here, we provided evidences using an electrophysiological method that RyR expressed in the plasma membrane of osteoclasts were able to conduct CaィイD12+ィエD1 ions for the first time.