Vodian M A, Nicoll C S
J Endocrinol. 1979 Jan;80(1):69-81. doi: 10.1677/joe.0.0800069.
The relationships were examined between the concentrations of GH determined by bioassay (rat tibia test) and radioimmunoassay in homogenates of rat adenohypophysial tissue and in the incubation medium in which the tissue had been maintained. Adenohypophyses from young male rats were incubated in Medium 199 with or without a putative synthetic GH-releasing factor (GRF) to achieve a dynamic state of GH secretion, but the GRF did not consistently stimulate the release of GH as measured by either bioassay or radioimmunoassay. Both assays gave closely similar values for the concentration of GH in homogenates of the adenohypophyses of undisturbed rats. When the two assays were used to measure the concentrations of GH in incubated pituitary tissue, the values showed no correlation, although the concentrations of GH in the incubation medium were again highly correlated. However, the bioassay : radioimmunoassay ratio for the secreted hormone [2.14 +/- 0.09 (S.E.M.)] was significantly higher than that for the intrapituitary form from the unincubated gland (0.93 +/- 0.06). By radioimmunoassay, secreted rat GH was found to be less stable than purified rat GH when the two forms were incubated in vitro with slices of various rat tissues. Similarly, the rate of clearance of secreted rat GH from the plasma of hypophysectomized rats, as determined by radioimmunoassay, was much faster than that of the purified GH. The biological activity of purified bovine GH was blocked by aprotinin, an inhibitor of proteolysis, but the drug had no inhibitory effect on the bioactivity of rat GH secreted into the incubation medium. Overall, these results indicate that secreted rat GH has properties intermediate between those of the intrapituitary form and the form found in the circulation.
采用生物测定法（大鼠胫骨试验）和放射免疫分析法，检测了大鼠腺垂体组织匀浆及组织培养介质中生长激素（GH）的浓度，并研究了二者之间的关系。将年轻雄性大鼠的腺垂体在含或不含假定的合成生长激素释放因子（GRF）的199培养基中孵育，以实现GH分泌的动态状态，但无论是生物测定法还是放射免疫分析法，GRF均未持续刺激GH的释放。对于未受干扰的大鼠腺垂体匀浆中GH的浓度，两种测定方法得出的数值非常相似。当使用这两种测定方法测量孵育后的垂体组织中GH的浓度时，数值之间没有相关性，尽管培养基中GH的浓度再次高度相关。然而，分泌激素的生物测定法与放射免疫分析法的比值[2.14±0.09（标准误）]显著高于未孵育腺体中垂体内部形式的该比值（0.93±0.06）。通过放射免疫分析法发现，当将分泌型大鼠GH和纯化的大鼠GH在体外与各种大鼠组织切片一起孵育时，分泌型大鼠GH不如纯化的大鼠GH稳定。同样，通过放射免疫分析法测定，去垂体大鼠血浆中分泌型大鼠GH的清除速率比纯化的GH快得多。纯化的牛GH的生物活性被蛋白水解抑制剂抑肽酶阻断，但该药物对分泌到培养基中的大鼠GH的生物活性没有抑制作用。总体而言，这些结果表明，分泌型大鼠GH的特性介于垂体内部形式和循环中发现的形式之间。
