Rendón M C, Toro M J, Mellado M, Montoya E
Catedra de Bioquímica, Facultad de Ciencias, Universidad de Cádiz, Puerto Real, Spain.
Second Messengers Phosphoproteins. 1988;12(2-3):75-81.
Somatostatin administration to female rats increased the activity of calmodulin-dependent soluble phosphodiesterase, both in pituitary and brain. This effect was also seen in homogenates of GH4C1 cells pretreated with the hormone. When assayed in the presence of EGTA no differences in rat brain and pituitary phosphodiesterase were observed between controls and somatostatin-treated, but when assayed in the presence of calcium or calcium plus calmodulin a clear increase in the activity of the enzyme was detected. In GH4C1 homogenates prepared from somatostatin-pretreated cells there was an increase in phosphodiesterase activity assayed in the presence of EGTA vs non-treated controls, which was more clear when assayed in the presence of calcium or calcium plus calmodulin. These observations suggest that somatostatin effects derive, at least in part, from increased cyclic nucleotide degradation.
给雌性大鼠注射生长抑素会增加垂体和大脑中钙调蛋白依赖性可溶性磷酸二酯酶的活性。在用该激素预处理的GH4C1细胞匀浆中也观察到了这种效应。在EGTA存在的情况下进行测定时，对照组和生长抑素处理组之间大鼠脑和垂体磷酸二酯酶未观察到差异，但在钙或钙加钙调蛋白存在的情况下进行测定时，检测到该酶的活性明显增加。在由生长抑素预处理细胞制备的GH4C1匀浆中，与未处理的对照组相比，在EGTA存在的情况下测定的磷酸二酯酶活性增加，在钙或钙加钙调蛋白存在的情况下进行测定时更明显。这些观察结果表明，生长抑素的作用至少部分源于环核苷酸降解增加。
