Fadda G Z, Thanakitcharu P, Comunale R, Lipson L G, Massry S G
Department of Medicine, University of Southern California School of Medicine, Los Angeles.
Kidney Int. 1991 Sep;40(3):413-7. doi: 10.1038/ki.1991.227.
Extrarenal disposal of potassium load is impaired in chronic renal failure (CRF). This has been attributed to excess PTH since extrarenal disposition of potassium is normal in CRF-PTX animals. Insulin augments potassium entry into cells and hyperkalemia stimulates insulin secretion. Since glucose-induced insulin secretion is impaired in CRF and normal in CRF-PTX, it is possible that K(+)-induced insulin secretion is also impaired in CRF due to excess PTH. Such a defect would contribute to the abnormality in extrarenal disposal of potassium in CRF. We examined K(+)-induced insulin secretion, cytosolic calcium ([Ca2+]i) and the changes in [Ca2+]i in response to 20 mM KCl of islets from normal, CRF, and CRF-PTX rats; and normal and CRF animals treated with verapamil (normal-V and CRF-V). K(+)-induced insulin secretion by islets isolated from CRF rats was significantly (P less than 0.01) lower than that from normal, CRF-PTX, CRF-V and normal-V rats. Basal level of [Ca2+]i in islets of CRF rats was significantly (P less than 0.01) higher than in islets of the other four groups of animals. The calcium signal (delta [Ca2+]i) and the delta [Ca2+]i/basal [Ca2+]i ratio in response to 20 mM KCl observed in islets from CRF rats were significantly lower than in the other four groups of animals.(ABSTRACT TRUNCATED AT 250 WORDS)
慢性肾衰竭（CRF）时肾脏外对钾负荷的处理功能受损。这归因于甲状旁腺激素（PTH）过多，因为在CRF - 甲状旁腺切除（PTX）动物中肾脏外钾的处理是正常的。胰岛素可增加钾进入细胞，高钾血症刺激胰岛素分泌。由于葡萄糖诱导的胰岛素分泌在CRF中受损而在CRF - PTX中正常，因此有可能CRF中由于PTH过多，钾诱导的胰岛素分泌也受损。这样的缺陷会导致CRF时肾脏外钾处理异常。我们检测了正常、CRF和CRF - PTX大鼠胰岛对20 mM氯化钾刺激时钾诱导的胰岛素分泌、细胞内钙浓度（[Ca2+]i）及其变化；以及用维拉帕米处理的正常和CRF动物（正常 - V和CRF - V）。从CRF大鼠分离的胰岛中钾诱导的胰岛素分泌显著低于（P < 0.01）正常、CRF - PTX、CRF - V和正常 - V大鼠。CRF大鼠胰岛的基础[Ca2+]i水平显著高于（P < 0.01）其他四组动物。CRF大鼠胰岛对20 mM氯化钾刺激的钙信号（δ[Ca2+]i）和δ[Ca2+]i/基础[Ca2+]i比值显著低于其他四组动物。（摘要截断于250字）
