Drug Discovery Research, Astellas Pharma Inc., Tsukuba, Japan.
Clin Exp Pharmacol Physiol. 2012 May;39(5):438-46. doi: 10.1111/j.1440-1681.2012.05693.x.
In the present study we examined the effects of high extracellular glucose concentrations on vasopressin (AVP) V(1A) receptor kinetics and signal transduction in cultured rat mesangial cells. Scatchard analysis of [(3) H]-AVP binding to mesangial cell plasma membranes showed that although high glucose (30 mmol/L) decreased V(1A) receptor numbers relative to cells cultured in normal glucose (10 mmol/L), receptor affinity was not affected. This V(1A) receptor downregulation was associated with an attenuated increase in AVP-stimulated cytosolic free calcium concentrations (Ca(2+) ). In addition, high glucose increased both the basal and AVP-stimulated activity of the classic mitogen-activated protein kinase, namely extracellular signal-regulated kinase (ERK). Furthermore, high glucose induced activation of protein kinase C (PKC) in mesangial cells that could be inhibited by coincubation with the PKC inhibitor staurosporine (10 nmol/L). Staurosporine also markedly attenuated the high glucose-induced downregulation of V(1A) receptors on mesangial cells and blocked the depressed Ca(2+) response and increased ERK activity induced by AVP. The results indicate that high extracellular glucose downregulates V(1A) receptors on rat mesangial cells and modulates their signal transduction properties via PKC activation.
在本研究中，我们研究了高细胞外葡萄糖浓度对培养的大鼠系膜细胞血管加压素（AVP）V（1A）受体动力学和信号转导的影响。[3H] - AVP 与系膜细胞质膜的结合的 Scatchard 分析表明，尽管高葡萄糖（30 mmol/L）与在正常葡萄糖（10 mmol/L）中培养的细胞相比降低了 V（1A）受体的数量，但受体亲和力不受影响。这种 V（1A）受体下调与 AVP 刺激的细胞浆游离钙浓度（[Ca2+]（i））增加减弱有关。此外，高葡萄糖增加了经典丝裂原激活的蛋白激酶，即细胞外信号调节激酶（ERK）的基础和 AVP 刺激的活性。此外，高葡萄糖诱导系膜细胞中蛋白激酶 C（PKC）的激活，该激活可被 PKC 抑制剂星形孢菌素（10 nmol/L）共孵育抑制。星形孢菌素还明显减弱了高葡萄糖诱导的系膜细胞 V（1A）受体下调，并阻断了 AVP 诱导的[Ca2+]（i）反应降低和 ERK 活性增加。结果表明，高细胞外葡萄糖下调大鼠系膜细胞上的 V（1A）受体，并通过 PKC 激活调节其信号转导特性。
