Kiyatake I
Department of Medicine, Juntendo University School of Medicine, Tokyo, Japan.
Nihon Jinzo Gakkai Shi. 1994 Jun;36(6):709-14.
Guanidinoacetic acid (GAA) is generally considered to be synthesized by glycine-amidinotransferase (GAT) in the renal tubular epithelial cells. The purpose of the present study was to determine serum, urinary and renal cortex GAA levels in streptozotocin (STZ) -induced diabetic rats with or without insulin treatment, for evaluating whether the GAA assay is a clinical marker for renal tubular dysfunction in diabetes. Urinary and serum samples, and renal cortex of the rats were obtained one, two and three weeks after the injection of 65 mg/kg of STZ. GAA and 1.5 anhydroglucitol (1. 5AG) levels were measured by HPLC. N-acetyl glucosaminidase (NAG) activity was determined by the enzymatic method. GAA levels in serum, urine and renal cortex from STZ-diabetic rats were significantly decreased compared with those of the control rats. The serum, urinary and renal cortex GAA levels were markedly ameliorated by insulin treatment. In contrast, urinary 1. 5AG levels and NAG activity were significantly increased in STZ-induced diabetic rats. Urinary NAG activity also returned to the control levels after insulin treatment. These results indicate that high serum glucose levels may influence GAA synthesis renal tubular epithelial cells in diabetes. The measurement of GAA is a useful indicator for renal tubular dysfunction in the early phase of diabetes mellitus.
胍基乙酸（GAA）通常被认为是由肾小管上皮细胞中的甘氨酸脒基转移酶（GAT）合成的。本研究的目的是测定链脲佐菌素（STZ）诱导的糖尿病大鼠在有无胰岛素治疗情况下的血清、尿液和肾皮质GAA水平，以评估GAA检测是否为糖尿病肾小管功能障碍的临床标志物。在注射65mg/kg STZ后的1周、2周和3周获取大鼠的尿液和血清样本以及肾皮质。通过高效液相色谱法（HPLC）测定GAA和1,5-脱水葡萄糖醇（1,5AG）水平。通过酶法测定N-乙酰氨基葡萄糖苷酶（NAG）活性。与对照大鼠相比，STZ诱导的糖尿病大鼠血清、尿液和肾皮质中的GAA水平显著降低。胰岛素治疗可显著改善血清、尿液和肾皮质中的GAA水平。相反，STZ诱导的糖尿病大鼠尿液中的1,5AG水平和NAG活性显著升高。胰岛素治疗后尿液中的NAG活性也恢复到对照水平。这些结果表明，高血糖水平可能影响糖尿病时肾小管上皮细胞中GAA的合成。GAA的检测是糖尿病早期肾小管功能障碍的有用指标。
