Hise M K, Mehta P S
University of Maryland Medical School, Department of Internal Medicine, Baltimore.
Kidney Int. 1989 Aug;36(2):216-21. doi: 10.1038/ki.1989.182.
The localization and activity of the calcium-sensitive phospholipid-dependent protein kinase C (PKC) were examined following the loss of 50% of functioning nephron mass. Four hours following unilateral nephrectomy in rats, soluble (100,000 g supernatant) proteins in the contralateral kidney were increased by 11% compared to sham operated controls; the increase was 33% 144 hours following surgery. The specific activity of PKC did not change in the cytosol at any of the time periods examined and averaged 63.9 +/- 8.2 pmol.mg-1.min-1 in unilaterally nephrectomized animals four hours following surgery. Four hours following sham surgery total soluble PKC activity averaged 1667.0 +/- 278.4 pmol.kidney-1.min-1, whereas activity averaged 3067.7 +/- 415.4 pmol.kidney-1.min-1 in animals post-nephrectomy (N = 5, P less than 0.04). Similar data was seen 144 hours following surgery. To examine the PKC activity in plasma membranes of proximal tubular cells, brush border membranes were prepared from rat kidney cortex. Twenty-four hours following unilateral nephrectomy, activity averaged 193.8 +/- 14.9 pmol.mg-1.min-1, while activity in membranes isolated from sham operated animals averaged 76.6 +/- 8.0 pmol.mg-1.min-1 (N = 5, P less than 0.001). Similar data was evident 48 hours following surgery. A small increment in activity was seen in the basolateral membrane preparation 24 hours following unilateral nephrectomy but not at 48 hours. These data indicate that cellular PKC activity increases rapidly following reductions in renal mass, and there are selective increments in the brush border membrane of the proximal tubular cell. The localization of PKC to this membrane may have important consequences for adaptations following nephron loss.
在功能性肾单位数量减少50%后，检测了钙敏感的磷脂依赖性蛋白激酶C（PKC）的定位和活性。大鼠单侧肾切除术后4小时，与假手术对照组相比，对侧肾脏中的可溶性（100,000g上清液）蛋白增加了11%；术后144小时增加了33%。在所检测的任何时间段内，细胞质中PKC的比活性均未发生变化，单侧肾切除动物术后4小时，其平均比活性为63.9±8.2 pmol·mg⁻¹·min⁻¹。假手术后4小时，总可溶性PKC活性平均为1667.0±278.4 pmol·肾⁻¹·min⁻¹，而肾切除术后动物的活性平均为3067.7±415.4 pmol·肾⁻¹·min⁻¹（N = 5，P<0.04）。术后144小时观察到类似的数据。为了检测近端肾小管细胞质膜中的PKC活性，从大鼠肾皮质制备了刷状缘膜。单侧肾切除术后24小时，活性平均为193.8±14.9 pmol·mg⁻¹·min⁻¹，而从假手术动物分离的膜中的活性平均为76.6±8.0 pmol·mg⁻¹·min⁻¹（N = 5，P<0.001）。术后48小时也观察到类似的数据。单侧肾切除术后24小时，基底外侧膜制剂中的活性有小幅增加，但48小时时未增加。这些数据表明，肾质量减少后细胞PKC活性迅速增加，并且近端肾小管细胞的刷状缘膜有选择性增加。PKC定位于该膜可能对肾单位丢失后的适应性有重要影响。
