Calcium signaling pathways utilized by P2X receptors in freshly isolated preglomerular MVSMC.
Calcium signaling pathways utilized by P2X receptors in freshly isolated preglomerular MVSMC.
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DOI：
10.1152/ajprenal.2001.280.6.f1054
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发表时间：
2001-06
期刊：
影响因子：
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通讯作者：
S. M. White;J. Imig;T. T. Kim-T.;B. Hauschild;E. Inscho
中科院分区：
文献类型：
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作者：
S. M. White;J. Imig;T. T. Kim-T.;B. Hauschild;E. Inscho
本研究验证了P2 X受体激活通过诱发电压依赖性钙内流增加肾小球前微血管平滑肌细胞（MVSMC）胞内Ca（2+）浓度（[Ca（2+）]（i））的假设。获得MVSMC，并加载钙敏感染料Fura 2，并通过使用单细胞荧光显微镜进行研究。通过使用P2 X受体选择性激动剂α，β-亚甲基-ATP评估P2 X受体激活对[Ca（2+）]（i）的影响，并与内源性P2受体激动剂ATP引起的反应进行比较。α，β-亚甲基-ATP增加[Ca（2+）]（i）呈剂量依赖性。在激动剂浓度为0.1、1和10 μ M时，[Ca（2+）]（i）的峰值增加分别平均为37 +/- 11、73 +/- 15和103 +/- 21 nM。由10 μ M α，β-亚甲基-ATP引起的平均峰值响应约为用10 μ M ATP获得的响应的34%。α，β-亚甲基-ATP诱导[Ca（2+）]（i）在[Ca（2+）]（i）恢复至基线之前短暂升高，而ATP诱导双相反应，包括峰值反应和持续平台期。在无Ca（2+）的培养液中，ATP可引起[Ca（2+）]（i）的瞬时性急剧增加，而对α，β-亚甲基-ATP的反应则消失。用10 μ M地尔硫卓或硝苯地平阻断Ca（2+）通道可减弱对α，β-亚甲基-ATP的反应，而用5 mM Ni（2+）非特异性阻断Ca（2+）内流途径则可消除该反应。用新型P2 X受体拮抗剂NF-279阻断P2 X受体完全但可逆地消除了对α，β-亚甲基-ATP的反应。这些结果表明，α，β-亚甲基-ATP激活P2 X受体增加肾小球前MVSMC [Ca（2+）]（i），部分是通过刺激电压依赖性Ca（2+）通过L型Ca（2+）通道内流。
This study tested the hypothesis that P2X receptor activation increases intracellular Ca(2+) concentration ([Ca(2+)](i)) in preglomerular microvascular smooth muscle cells (MVSMC) by evoking voltage-dependent calcium influx. MVSMC were obtained and loaded with the calcium-sensitive dye fura 2 and studied by using single-cell fluorescence microscopy. The effect of P2X receptor activation on [Ca(2+)](i) was assessed by using the P2X receptor-selective agonist alpha,beta-methylene-ATP and was compared with responses elicited by the endogenous P2 receptor agonist ATP. alpha,beta-Methylene-ATP increased [Ca(2+)](i) dose dependently. Peak increases in [Ca(2+)](i) averaged 37 +/- 11, 73 +/- 15, and 103 +/- 21 nM at agonist concentrations of 0.1, 1, and 10 microM, respectively. The average peak response elicited by 10 microM alpha,beta-methylene-ATP was approximately 34% of the response obtained with 10 microM ATP. alpha,beta-Methylene-ATP induced a transient increase in [Ca(2+)](i) before [Ca(2+)](i) returned to baseline, whereas ATP induced a biphasic response including a peak response followed by a sustained plateau. In Ca(2+)-free medium, ATP induced a sharp transient increase in [Ca(2+)](i), whereas the response to alpha,beta-methylene-ATP was abolished. Ca(2+) channel blockade with 10 microM diltiazem or nifedipine attenuated the response to alpha,beta-methylene-ATP, whereas nonspecific blockade of Ca(2+) influx pathways with 5 mM Ni(2+) abolished the response. Blockade of P2X receptors with the novel P2X receptor antagonist NF-279 completely but reversibly abolished the response to alpha,beta-methylene-ATP. These results indicate that P2X receptor activation by alpha,beta-methylene-ATP increases [Ca(2+)](i) in preglomerular MVSMC, in part, by stimulating voltage-dependent Ca(2+) influx through L-type Ca(2+) channels.