Ascoli M, Puett D
Endocrinology. 1976 Nov;99(5):1237-43. doi: 10.1210/endo-99-5-1237.
The renal clearance of tritiated and methylated ovine pituitary luteinizing hormone (LH) has been determined in mature male rats, and the urinary product has been characterized with regard to molecular size, charge, and heterogeneity. [3H]Methylated-LH was found to have a renal clearance of 0.17+/-0.03 ml/min/100 g body weight, compared to a value of 0.99+/-0.18 for tritiated inulin. This indicates that LH is not secreted and that much of the filtered hormone is reabsorbed from the tubular lumen. Evidence is presented which shows that urinary ovine [3H]methylated-LH is not extensively degraded; yet, the biological potency is only 10-20% that of pituitary and serum LH. The large reduction in potency is a result of excretion since the in vitro incubation of LH with urine does not produce the same effect. The biotransformation occurring during excretion results in charge heterogeneity of LH; this may arise from either inhibitor binding or enzymic alterations.
已在成年雄性大鼠中测定了氚标记和甲基化的绵羊垂体促黄体生成素（LH）的肾清除率，并对尿产物的分子大小、电荷和异质性进行了表征。发现[3H]甲基化-LH的肾清除率为0.17±0.03 ml/分钟/100克体重，而氚标记菊粉的值为0.99±0.18。这表明LH不被分泌，且大部分滤过的激素从肾小管腔中被重吸收。有证据表明，尿中的绵羊[3H]甲基化-LH没有被广泛降解；然而，其生物活性仅为垂体和血清LH的10%-20%。活性大幅降低是排泄的结果，因为LH与尿液的体外孵育不会产生相同的效果。排泄过程中发生的生物转化导致LH的电荷异质性；这可能是由于抑制剂结合或酶促改变引起的。
