Studies on the requlatory mechanisms of renal glomerular and tubular functions.

我们在本研究项目中获得的主要发现如下。1)系膜细胞表达转化生长因子-βmRNA，其表达受胎牛血清和蛋白激酶C的刺激。系膜细胞产生的转化生长因子-β几乎全部以潜伏状态释放到条件培养液中。外源性加入转化生长因子-β可抑制系膜细胞的生长。3)克隆的肾小管细胞LLC-PK1细胞表达单一的PAF受体mRNA，PAF可诱导LLC-PK1细胞发生剂量依赖性钙瞬变。4)Endothelin-1可剂量依赖性地增加皮质和髓质集合管[Ca~(2+)]i。除肾小球外，ET-1mRNA仅在皮质和髓质集合管中表达，且在肾小球和集合管中有明显的结合。5)基于对培养的肾小球系膜细胞的观察，我们提出了关于肾小管-肾小球反馈中跨细胞信号转导的假说。

The major findings we obtained in this research project are as follows. 1) Mesangial cell expressed TGF-beta mRNA and its expression is stimulated by the addition of fetal calf serum and protein kinase C.Almost all the TGF-beta produced by mesangial cell and released into condition medium is in a latent form. Exogenously added TGF-beta inhibited mesangial cell growth. 2) A single class of PAF receptor is present in the quinea pig kidney which is most abundant in the cortex 3) Cloned renal tubule cells, LLC-PK1 cells, express a single entity of PAF receptor mRNA and PAF induced a dose-dependent calcium transients in LLC-PK1 cells. 4) Endothelin-1 dose-dependently increased [Ca^<++>]i both in cortical and medullary collecting duct. Endothelin-1 mRNA was found to be expressed only in cortical and medullary collecting ducts in addition to glomeruli and endothelin-1 binding occurs significantly in glomeruli and collecting tubules. 5) We proposed our hypothesis concerning the transcellular signal transduction in tubulo-glomerular feedback based on the observations we obtained in cultured mesangial cells.