Melick R A, Farrugia W, Heaton C L, Quelch K J, Scoggins B A, Wark J D
University of Melbourne Department of Medicine, Royal Melbourne Hospital, Victoria, Australia.
Calcif Tissue Int. 1988 Mar;42(3):185-90. doi: 10.1007/BF02556332.
Plasma osteocalcin has been proposed as a useful and convenient biochemical marker of bone formation. However, the effect on plasma osteocalcin due to variations in the rate of its removal from the circulation has been little investigated. We have measured the metabolic clearance rate of plasma osteocalcin in adult oophorectomized sheep. Two methods were used: intravenous bolus injection (six animals) and 6 hour constant intravenous infusion (four animals) of 125I-ovine osteocalcin. Using the bolus injection method, the plasma clearance of osteocalcin was found to be 3.3 liters/h. With the constant infusion method, the calculated value was 2.8 liters/h; based on this value and the mean ovine plasma osteocalcin concentration of 26.9 ng/ml (N = 29), a plasma production rate of 1.8 mg/day was derived. Osteocalcin clearance was relatively constant among animals in a basal state. Hence, the present approach should permit us to evaluate the relative contributions to changes in circulating osteocalcin levels from altered osteocalcin plasma clearance and production under various physiological and pathological conditions.
血浆骨钙素已被提议作为一种有用且便捷的骨形成生化标志物。然而，关于循环中骨钙素清除速率变化对血浆骨钙素的影响，此前鲜有研究。我们测定了成年去卵巢绵羊血浆骨钙素的代谢清除率。采用了两种方法：对6只动物进行静脉推注（注射125I-羊骨钙素），对4只动物进行6小时持续静脉输注（125I-羊骨钙素）。采用推注法时，发现骨钙素的血浆清除率为3.3升/小时。采用持续输注法时，计算值为2.8升/小时；基于该值以及羊血浆骨钙素的平均浓度26.9纳克/毫升（N = 29），得出血浆生成率为1.8毫克/天。在基础状态下，动物之间的骨钙素清除相对恒定。因此，目前的方法应能让我们评估在各种生理和病理条件下，骨钙素血浆清除和生成的改变对循环骨钙素水平变化的相对贡献。
