Lakatua D J, Blomquist C H, Haus E, Sackett-Lundeen L, Berg H, Swoyer J
Am J Clin Pathol. 1982 Jul;78(1):69-77. doi: 10.1093/ajcp/78.1.69.
Urinary N-acetyl-beta-glucosaminidase (NAG), a lysosomal enzyme of renal tubular origin, has been shown to be a sensitive indicator of renal tubular function. This study documents a circadian rhythm in the urinary activity of NAG, statistically validated and quantified by the cosinor method, in 19 female and 15 male human subjects. The acrophase of the circadian rhythm in urinary NAG activity occurs at 09(40) with 95% confidence limits between 08(40) and 12(08) and is similar to the timing of the circadian rhythm in urinary free cortisol. The circadian acrophase of urinary NAG activity lags in timing the circadian rhythms in urine volume, Na and K excretion, and urinary free adrenalin and noradrenalin, by about five to ten hours and the circadian rhythm in creatinine excretion by about 11 hours. These functions with their characteristic phase relations are part of the internal circadian time structure of the human organism, and may provide internal phase references, independent of the "time of day." This study also documents a sex difference in mesor of the circadian rhythms in urinary NAG activity, with female subjects having a higher mesor and amplitude than the male subjects, and in the excretion of creatinine and potassium, with male subjects having a higher mesor and amplitude than the female subjects.
尿N-乙酰-β-氨基葡萄糖苷酶（NAG）是一种源于肾小管的溶酶体酶，已被证明是肾小管功能的敏感指标。本研究记录了19名女性和15名男性人类受试者尿NAG活性的昼夜节律，通过余弦法进行了统计学验证和量化。尿NAG活性昼夜节律的峰值相位出现在09(40)，95%置信区间在08(40)至12(08)之间，与尿游离皮质醇的昼夜节律时间相似。尿NAG活性的昼夜峰值相位在尿量、钠和钾排泄、尿游离肾上腺素和去甲肾上腺素的昼夜节律时间上滞后约五到十个小时，在肌酐排泄的昼夜节律时间上滞后约11个小时。这些具有特征相位关系的功能是人类机体内部昼夜时间结构的一部分，可能提供独立于“一天中的时间”的内部相位参考。本研究还记录了尿NAG活性昼夜节律中值的性别差异，女性受试者的中值和幅度高于男性受试者，在肌酐和钾排泄方面，男性受试者的中值和幅度高于女性受试者。
