Hagiwara M, Inagaki M, Kanamura K, Ohta H, Hidaka H
Department of Molecular and Cellular Pharmacology, Mie University School of Medicine, Japan.
J Pharmacol Exp Ther. 1988 Jan;244(1):355-60.
Aminoglycosides such as neomycin are commonly prescribed antibiotics; however, there is associated serious damage to the kidney. We examined the effect of aminoglycoside antibiotics on renal protein phosphorylation and found that neomycin selectively inhibited Ca++-activated, phospholipid-dependent phosphorylation of 88-kDa protein in cell lysates of the rabbit kidney. Fifty percent inhibition of phosphorylation of this protein occurred with 5 X 10(-5) to 1 X 10(-4) M neomycin. In living PtK2 cells, neomycin dose-dependently inhibited 12-O-tetradecanoyl-phorbol-13-acetate-induced phosphorylation of 88 K Da protein. This drug also inhibited phosphorylation of exogenous protein catalyzed by protein kinase C, isolated from rabbit kidney in vitro. In contrast, neomycin had little or no inhibitory effect on cyclic GMP-dependent protein kinase, cyclic AMP-dependent protein kinase, casein kinase I, casein kinase II and Ca++-calmodulin-dependent myosin light chain kinase. Whereas activity of protein kinase C was inhibited 65% by neomycin (0.1 mM) at pH 5 to 7, inhibition decreases to 33% at pH 8 and to zero at pH 9. The potencies of a series of aminoglycoside antibiotics to inhibit the kinase agreed well with number of ionizable amino groups of compounds (gamma = 0.99) and this also approximates their known nephrotoxic potential; amikacin less than or equal to kanamycin less than gentamycin less than or equal to tobramycin less than neomycin. As aminoglycoside antibiotics present in the kidney after administration of toxicological doses (10(-2) M) will inhibit the effects of protein kinase C, the aminoglycoside antibiotics-induced nephrotoxicity is discussed in relation to inhibition of intracellular protein kinase C.
新霉素等氨基糖苷类药物是常用的抗生素；然而，它们会对肾脏造成严重损害。我们研究了氨基糖苷类抗生素对肾脏蛋白质磷酸化的影响，发现新霉素能选择性抑制兔肾细胞裂解物中中中霉素能选择性抑制兔肾细胞裂解物中88 kDa蛋白质的Ca++激活的磷脂依赖性磷酸化。5×10(-5)至1×10(-4) M新霉素可使该蛋白质的磷酸化受到50%的抑制。在活的PtK2细胞中，新霉素剂量依赖性地抑制12-O-十四烷酰佛波醇-13-乙酸酯诱导的88 kDa蛋白质的磷酸化。这种药物还能抑制体外从兔肾中分离出的蛋白激酶C催化的外源蛋白质的磷酸化。相比之下，新霉素对环鸟苷酸依赖性蛋白激酶、环腺苷酸依赖性蛋白激酶、酪蛋白激酶I、酪蛋白激酶II和Ca++-钙调蛋白依赖性肌球蛋白轻链激酶几乎没有抑制作用。在pH 5至7时，新霉素（0.1 mM）可使蛋白激酶C的活性受到65%的抑制，在pH 8时抑制率降至33%，在pH 9时降至零。一系列氨基糖苷类抗生素抑制该激酶的效力与化合物可电离氨基的数量高度相关（γ = 0.99），这也与它们已知的肾毒性潜力相符；阿米卡星≤卡那霉素＜庆大霉素≤妥布霉素＜新霉素。由于给予毒理学剂量（10(-2) M）后肾脏中存在的氨基糖苷类抗生素会抑制蛋白激酶C的作用，因此讨论了氨基糖苷类抗生素诱导的肾毒性与细胞内蛋白激酶C抑制的关系。
