Department of Foods and Nutrition, Purdue University, 700 W. State Street, West Lafayette, IN 47907, USA.
Bone. 2010 May;46(5):1238-43. doi: 10.1016/j.bone.2010.02.003. Epub 2010 Feb 8.
Techniques for assessing bone dynamic are in high demand. Calcium (Ca) kinetic studies are currently being used in our clinical studies of bone turnover in adolescents and elderly. The technique has rarely been compared to the standard method of bone dynamic histomorphometry. We perturbed bone turnover through ovariectomy and sub-optimal dietary Ca in a female rat model to cross-calibrate Ca kinetics against dynamic histomorphometry. Kinetic studies involved oral and intravenous administration of (45)Ca and monitoring the tracer in blood, urine, feces, and bone over a 3-day period as part of a metabolic Ca balance study. Histomorphometric indices of mineral apposition rate, mineralizing surface, and bone formation rate were obtained from proximal metaphysis and mid-diaphysis region of tibial bone. Bone mineralization and resorption rates at the whole skeletal level as evaluated by kinetic studies were significantly correlated with the volume-based bone formation rate (BFR/BV) evaluated by dynamic histomorphometry in metaphyseal trabecular bone (r=0.72 and r=0.61, respectively, p<0.001) and surface-based bone formation rate (BFR/BS) in tibial cortex (r=0.63, p<0.001 and r=0.59, p<0.01, respectively). Significant correlations were also demonstrated between bone resorption and mineralization rates at the whole skeletal level (r=0.91, p<0.001) using (45)Ca kinetic data. Ca kinetic modeling showed an increase (p<0.001) in skeletal resorption and formation rates in response to ovariectomy (27.6 vs. 13.8 mg/d for bone resorption and 42.7 vs. 28 mg/d for bone formation in ovariectomized vs. their Sham-operated control animals, respectively). Ca kinetic data also showed that bone formation decreased by 30% and whole bone balance by 50%, when dietary Ca level was reduced from 0.4% to 0.2% (34.2 vs. 23.8 mg/d and 10.4 vs. 5.1 mg/d, respectively, p<0.001). Our data suggest that Ca kinetic studies can be used reliably to rapidly detect changes in bone turnover at the whole skeletal level in response to interventions.
骨动态评估技术的需求很高。目前，我们在青少年和老年人的骨转换临床研究中使用钙（Ca）动力学研究。该技术很少与骨动力学组织形态计量学的标准方法进行比较。我们通过卵巢切除术和低钙饮食在雌性大鼠模型中干扰骨转换，以将 Ca 动力学与动态组织形态计量学交叉校准。动力学研究包括口服和静脉给予（45）Ca，并在代谢性 Ca 平衡研究中监测 3 天内血液、尿液、粪便和骨骼中的示踪剂。从胫骨近端干骺端和中段区域获得矿物沉积率、矿化表面和骨形成率的组织形态计量学指数。通过动力学研究评估的整个骨骼水平的骨矿化和骨吸收率与通过动态组织形态计量学评估的基于体积的骨形成率（BFR/BV）（在骺板小梁骨中分别为 r=0.72 和 r=0.61，p<0.001）和基于表面的骨形成率（BFR/BS）（在胫骨皮质中 r=0.63，p<0.001 和 r=0.59，p<0.01）具有显著相关性。通过（45）Ca 动力学数据还证明了整个骨骼水平的骨吸收和矿化率之间存在显著相关性（r=0.91，p<0.001）。Ca 动力学建模显示，卵巢切除术后骨骼吸收和形成率增加（p<0.001）（骨吸收分别为 27.6 和 13.8 mg/d，骨形成分别为 42.7 和 28 mg/d，卵巢切除组与假手术对照组相比）。Ca 动力学数据还表明，当饮食钙水平从 0.4%降至 0.2%时，骨形成减少 30%，整个骨平衡减少 50%（分别为 34.2 和 23.8 mg/d，10.4 和 5.1 mg/d，p<0.001）。我们的数据表明，Ca 动力学研究可用于可靠地快速检测干预后整个骨骼水平骨转换的变化。
