Matsunobu T, Schacht J
Kresge Hearing Research Institute, University of Michigan, Ann Arbor 48109-0506, USA.
J Comp Neurol. 2000 Jul 31;423(3):452-61.
We demonstrate here that nitric oxide (NO) attenuates ATP-evoked calcium transients in Deiters' and Hensen's cells, "supporting" (nonsensory) cells of the guinea pig cochlea, by means of activation of soluble guanylyl cyclase and protein kinase G. The enzymatic activities associated with the nitric oxide/cGMP/protein kinase G pathway had previously been demonstrated to be present in Deiters' and Hensen's cells. We now isolate these cells and measure changes in intracellular free calcium by using the calcium indicator fluo-3. In Deiters' cells, calcium increased rapidly in response to the application of ATP. The increase was attenuated when the pathway was stimulated by NO donors (diethylamine NONOate or sodium nitroprusside) or the cyclic GMP analog, 8-bromo-cyclic GMP. When the activation of the pathway was blocked by the additional presence of inhibitors of soluble guanylyl cyclase (LY83583) or protein kinase G (Rp-8-bromo-cyclic GMP or KT5823), the response to ATP was restored. The reactions also occurred in calcium-free media. Hensen's cells responded similarly. These results provide evidence that intracellular calcium is regulated by the NO/cGMP/protein kinase G pathway in the inner ear.
我们在此证明，一氧化氮（NO）通过激活可溶性鸟苷酸环化酶和蛋白激酶G，减弱了豚鼠耳蜗中Deiters细胞和Hensen细胞（“支持”性[非感觉]细胞）中ATP诱发的钙瞬变。先前已证明，与一氧化氮/cGMP/蛋白激酶G途径相关的酶活性存在于Deiters细胞和Hensen细胞中。我们现在分离出这些细胞，并使用钙指示剂fluo-3测量细胞内游离钙的变化。在Deiters细胞中，施加ATP后钙迅速增加。当该途径受到NO供体（二乙胺NONOate或硝普钠）或环GMP类似物8-溴环GMP刺激时，这种增加会减弱。当可溶性鸟苷酸环化酶抑制剂（LY83583）或蛋白激酶G抑制剂（Rp-8-溴环GMP或KT5823）的额外存在阻断该途径的激活时，对ATP的反应得以恢复。这些反应也发生在无钙培养基中。Hensen细胞的反应类似。这些结果提供了证据，表明内耳中的细胞内钙受NO/cGMP/蛋白激酶G途径调控。
