Jung A, Mayer G P, Hurst J G, Neer R, Potts J T
Am J Physiol. 1982 Jan;242(1):R141-50. doi: 10.1152/ajpregu.1982.242.1.R141.
A model for parathyroid gland response to differing calcium and magnesium concentrations is proposed based on direct determinations of parathyroid hormone (PTH) secretion rate. A proportional control seems adequate for physiological variations of calcium and magnesium levels. At extreme hypocalcemia, nonlinearities are observed: a model involving the depletion of a storage compartment is proposed, the size of which is calculated. PTH distribution was studied in another group of animals; sampling was made from the saphenous artery and the thoracic duct. Concentrations of plasma and lymph-intact PTH and carboxy-terminal fragments were determined by means of two different radioimmunoassays. The analysis of the results leads to the formulation of a five-compartment model, which shows that the metabolism of intact PTH is only partly due to the formation of carboxy-terminal fragments, most being directly secreted or catabolized. Linking these models for secretion and distribution of PTH, simulation studies were undertaken and compared with published data. This model is then discussed in comparison with previous work concerning other polypeptide hormones.
基于对甲状旁腺激素（PTH）分泌率的直接测定，提出了一种甲状旁腺对不同钙和镁浓度反应的模型。比例控制似乎足以应对钙和镁水平的生理变化。在极端低钙血症时，会观察到非线性现象：提出了一个涉及储存隔室耗竭的模型，并计算了其大小。在另一组动物中研究了PTH的分布；从隐动脉和胸导管进行采样。通过两种不同的放射免疫测定法测定血浆和淋巴中完整PTH及羧基末端片段的浓度。对结果的分析得出了一个五室模型，该模型表明完整PTH的代谢仅部分归因于羧基末端片段的形成，大部分是直接分泌或分解代谢。将这些PTH分泌和分布模型联系起来，进行了模拟研究并与已发表的数据进行了比较。然后将该模型与先前关于其他多肽激素的研究工作进行了比较讨论。
