The by-pass of tissue hormone stores during the secretion of newly synthesized parathyroid hormone.
The by-pass of tissue hormone stores during the secretion of newly synthesized parathyroid hormone.
复制标题
在新合成的甲状旁腺激素分泌过程中，组织激素储存的旁路。
作者：
R. MacGregor;J. Hamilton;D. V. Cohn
将牛甲状旁腺切片置于含[3-H]亮氨酸的Krebs‘s缓冲液中孵育，以测定甲状旁腺激素(PTH)的生物合成和分泌。孵育后，用脱氧胆酸钠提取组织的颗粒结构，提取液中主要生成新合成的(放射性)甲状旁腺素，残留物中生成预先存在的颗粒甲状旁腺素。在脉冲追逐实验中，放射性PTH在总组织放射性激素下降的同时进入颗粒组分，这表明新合成的PTH被包裹在这些颗粒中。孵育液中甲状旁腺激素的比放射性比组织的颗粒状甲状旁腺素高20倍至80多倍，但与组织新合成的激素的放射性大小相似。新合成的甲状旁腺素在含1.25 mM钙的缓冲液中的分泌量高于在2.5 mM钙的缓冲液中，这表明激素的释放受到生理控制。1.25 mM钙孵育的组织颗粒组分的甲状旁腺素含量低于2.5 mM钙孵育的组织颗粒部分。排除了孵育液中PT1的比放射性高于分泌颗粒组分的可能性，这是由于[3-H]亮氨酸在组织切片中的扩散梯度所致。这些数据表明，新合成的甲状旁腺素的大部分是在没有事先与分泌颗粒池中的激素平衡的情况下分泌的。
Bovine parathyroid gland slices were incubated in Krebs' buffer with [3-H] leucine in order to assess the biosynthesis and secretion of parathyroid hormone (PTH). After incubation the particulate structures of the tissue were extracted with sodium deoxycholate to yield primarily newly synthesized (radioactive) PTH in the extract and preexisting granule PTH in the residue. In pulse-chase experiments radioactive PTH entered the granule fraction at a time when total tissue radioactive hormone was declining, which indicates that some newly-synthesized PTH was packaged into these granules. The specific radioactivity of the PTH in the incubation medium was from 20-fold to more than 80-fold greater than that of the granule PTH of the tissue, but was similar in magnitude to that of the tissue's newly synthesized hormone. Secretion of newly synthesized PTH was greater during incubation in buffer with 1.25 mM Ca than it was at 2.5 mM Ca which indicated that the hormone release was subject to physiological control. The PTH content of the tissue granule fraction was lower following incubation at 1.25 mM Ca than at 2.5 mM Ca. The possibility was excluded that the higher specific radioactivity of PT1 of incubation medium compared to that of the secretory granule fraction resulted from a diffusion gradient of [3-H] leucine into the tissue slices. These data indicate that a major portion of the newly synthesized PTH was secreted without prior equilibration with the hormone in the pool of secretory granules.