Ouardani M, Travo P, Rakotoarivony J, Leung-Tack J
INSERM U 388, Institut Louis Bugnard, CHU Rangueil, Toulouse/France.
Eur J Cell Biol. 1997 Jul;73(3):232-9.
The contractile response to bradykinin (BK), measured by the reduction of the planar surface area, was studied in glomeruli and mesangial cells (MC) isolated from diabetic rats (D) one week after diabetes induction with injection of streptozotocin (STZ; 60 mg kg-1, i.p.). Results were compared with age and weight-matched untreated rats (N) and were expressed by two parameters of cell activity, the mean maximum contraction (MMC) and the proportion of contractile cells (PCC). Glomerular and mesangial contraction were found to be clearly reduced in diabetic rats in response to 100 nM BK. The lower contractile response was associated with a decrease of both glomerular calcium uptake and mesangial cell intracellular calcium mobilization. The fact that cell pretreatment with two protein kinase C (PKC) inhibitors, phorbol 12-13 myristate acetate and calphostin, lowered normal cell contraction at the level of that found in diabetic MC without any significant effect in the latter, suggests the involvement of a PKC pathway, perhaps by a decrease of activatable PKC in diabetes. In addition, our results led to the first description of a possible role of the kallikrein-kinin system in the early glomerular hemodynamic changes occurring in diabetes. Insulin (1-200 nM) increased the contractile response of cultured diabetic cells (MMC), and in this case, it also increased the PCC. It must be stressed that the effect of 1 nM insulin on the former (88% increase) was very much smaller than its effect on the latter (103% increase). The combination of the two parameters (contraction index, CI) provided a realistic evaluation of the contractile capacities of the cell population of the cultures as a whole. The differences in this index between normal and diabetic cell populations, in the absence or presence of insulin, were strictly parallel to those found in intact glomeruli. Finally, our results further confirm (Ouardani et al., Biol. Cell 86, 127, (1996)) the limit of the first five cell passages within which cultured MC can be reasonably used for the study of contractile abnormalities occurring in the early steps of diabetic state.
通过测量平面表面积的减少来研究缓激肽（BK）对从糖尿病大鼠（D）分离的肾小球和系膜细胞（MC）的收缩反应。糖尿病大鼠在腹腔注射链脲佐菌素（STZ；60mg/kg）诱导糖尿病一周后分离细胞。将结果与年龄和体重匹配的未处理大鼠（N）进行比较，并通过细胞活性的两个参数，即平均最大收缩（MMC）和收缩细胞比例（PCC）来表示。发现糖尿病大鼠肾小球和系膜对100 nM BK的收缩明显减弱。较低的收缩反应与肾小球钙摄取和系膜细胞内钙动员的减少有关。用两种蛋白激酶C（PKC）抑制剂佛波醇12 - 13肉豆蔻酸酯和钙磷蛋白对细胞进行预处理，可使正常细胞收缩降低到糖尿病MC的水平，而对后者无显著影响，这表明PKC途径参与其中，可能是由于糖尿病中可激活的PKC减少。此外，我们的结果首次描述了激肽释放酶 - 激肽系统在糖尿病早期肾小球血流动力学变化中可能的作用。胰岛素（1 - 200 nM）增加了培养的糖尿病细胞的收缩反应（MMC），在这种情况下，它也增加了PCC。必须强调的是，1 nM胰岛素对前者的作用（增加88%）远小于对后者的作用（增加103%）。这两个参数（收缩指数，CI）的组合为整体培养物中细胞群体的收缩能力提供了实际评估。在有无胰岛素的情况下，正常和糖尿病细胞群体在该指数上的差异与完整肾小球中的差异严格平行。最后，我们的结果进一步证实了（Ouardani等人，《生物细胞》86，127，（1996））前五代细胞的局限性，在此范围内培养的MC可合理用于研究糖尿病状态早期发生的收缩异常。
