Baumann G, Stolar M W, Buchanan T A
Endocrinology. 1985 Oct;117(4):1309-13. doi: 10.1210/endo-117-4-1309.
The 20,000-dalton variant of human GH (hGH) (20 K) exhibits full growth-promoting bioactivity in the rat despite its poor interaction with GH receptors, as compared to the principal 22,000-dalton form of hGH (22 K). To test the possibility that prolonged survival time of 20 K in vivo may contribute to this apparent discrepancy, we compared the MCRs of 22 K and 20 K in the rat by the single injection technique. Both radiolabeled and native 22 K and 20 K were examined in this regard. The MCR of 20 K was 2- to 3-fold lower than that of 22 K, a statistically significant difference (P less than 0.05). The distribution volumes were similar for the two hGH forms and corresponded approximately to the extracellular fluid space. We conclude that the prolonged persistence of 20 K in the circulation may contribute to its higher than expected bioactivity in vivo in the rat.
人生长激素（hGH）的20000道尔顿变体（20K）在大鼠体内表现出完全的促生长生物活性，尽管与主要的22000道尔顿形式的hGH（22K）相比，它与生长激素受体的相互作用较差。为了测试20K在体内的较长存活时间可能导致这种明显差异的可能性，我们通过单次注射技术比较了大鼠体内22K和20K的代谢清除率（MCR）。在这方面，我们对放射性标记的以及天然的22K和20K都进行了检测。20K的MCR比22K低2至3倍，这是一个具有统计学意义的差异（P小于0.05）。两种hGH形式的分布容积相似，并且大约对应于细胞外液空间。我们得出结论，20K在循环中的较长持续时间可能是其在大鼠体内具有高于预期的生物活性的原因。
