Characteristics of the post-somatostatin rebound in growth hormone secretion from perifused somatotrophs.
Characteristics of the post-somatostatin rebound in growth hormone secretion from perifused somatotrophs.
复制标题
生长激素抑制素后灌注生长激素细胞生长激素分泌反弹的特征。
作者：
J. Cowan;B. Moor;A. Chow;J. Kraicer
分散的大鼠生长激素细胞灌注重复步骤SRIF信号的10或60分钟（100 ng/ml）分开45分钟的控制期。测定流出物的大鼠GH（RIA）。GH分泌的最大抑制（信号）或完全恢复（关闭信号）发生在1分钟内。重复信号诱发相同的标准化反应。GH释放下降至对照的67 +/-（SE）2%（10分钟SRIF信号）和59 +/- 4%（60分钟SRIF信号）。去除SRIF后，观察到GH分泌的主要过冲，持续21 +/- 2 min（10 min或60 min SRIF步骤后）。尽管过冲持续时间恒定，但在较长的SRIF信号后，过冲导致的峰值分泌率和总分泌量更大。然而，60分钟SRIF暴露后过冲期间的额外分泌仅含有SRIF抑制的分泌的23 +/- 3%，而10分钟SRIF暴露后的额外分泌含有SRIF暴露抑制的量的79 +/- 12%，表明细胞内反馈在SRIF暴露一段时间后减缓了容易释放的GH的积累。在超调期间，观察到的峰值分泌速率是对照速率的两倍（和SRIF抑制速率的3.5倍）。注意到这些过冲和GH分泌的体内爆发之间的相似性。
Dispersed rat somatotrophs were perifused with repeated step SRIF signals of 10 or 60 min (100 ng/ml) separated by 45-min control periods. Effluent was assayed for rat GH (RIA). Maximum suppression of GH secretion (on signal) or complete recovery (off signal) occurred within 1 min. Repeated signals evoked identical normalized responses. GH release fell to 67 +/- (SE) 2% of control with 10-min SRIF signals and 59 +/- 4% of control with 60-min SRIF signals. After SRIF removal, major overshoots of GH secretion were observed, lasting 21 +/- 2 min (after 10-min or 60-min SRIF steps). Peak secretion rates and total secretion due to the overshoot were greater after longer SRIF signals, despite the constant duration of the overshoot. However, the extra secretion during overshoots after 60-min SRIF exposure contained only 23 +/- 3% of the secretion suppressed by SRIF, whereas the extra secretion after 10-min SRIF exposure contained 79 +/- 12% of the amount suppressed by the SRIF exposure, suggesting an intracellular feedback which slows accumulation of readily releasable GH after a period of SRIF exposure. During overshoot, peak secretion rates of twice the control rate (and 3.5 times the SRIF-inhibited rate) were observed. Similarities between these overshoots and in vivo bursts of GH secretion are noted.