钴对离体大鼠胰岛胰岛素分泌和钙摄取的抑制作用。

Cobalt inhibition of insulin secretion and calcium uptake by isolated rat islets.

作者信息

Henquin J C, Lambert A E

出版信息

Am J Physiol. 1975 Jun;228(6):1669-77. doi: 10.1152/ajplegacy.1975.228.6.1669.

DOI:10.1152/ajplegacy.1975.228.6.1669

Abstract

Cobalt (Co'++) inhibited glucose-, leucine-, and K'+-induced immunoreactive insulin (IRI)release by isolated rat islets. This inhibition of the insulinotropic effect of glucose was dose dependent, affected both phases of secretion, was very rapid, and was well reversible. It exhibited a kinetics similiar to that of Ca'++ omission, and the metal (2.5 mM) prevented Ca'++ reintroduction from restoring a normal rate of IRI release. Theophylline (2 mM) partially overcame the inhibitory effect of 0.5 mM Co'++, but not that of 2.5 mM. Glucose-induced secretion was lessmarkedly reduced by 0.5 mM Co'++ in the absence of Mg'++ or in the presence of 7.5 mM Ca'++. Even at 12.5 mM, the metal did not alter glucose oxidation by theislets. By contrast, Ca uptake by islet cells was reversibly diminished (55%) in the presence of 1.25 mM Co'++. Calcium influx (measured after 2.5 min) was aslo reduced by Co'++ to a degree that did not change after longer incubation periods. It is concluded that Co'++ inhibits IRI release mainly through an antaognistic action on Ca entry in beta cells.

摘要

钴（Co²⁺）抑制离体大鼠胰岛由葡萄糖、亮氨酸和K⁺诱导的免疫反应性胰岛素（IRI）释放。这种对葡萄糖促胰岛素作用的抑制呈剂量依赖性，影响分泌的两个阶段，非常迅速且易于逆转。它表现出与省略Ca²⁺相似的动力学，并且该金属（2.5 mM）阻止重新引入Ca²⁺后恢复正常的IRI释放速率。茶碱（2 mM）部分克服了0.5 mM Co²⁺的抑制作用，但不能克服2.5 mM Co²⁺的抑制作用。在不存在Mg²⁺或存在7.5 mM Ca²⁺的情况下，0.5 mM Co²⁺对葡萄糖诱导的分泌的减少不太明显。即使在12.5 mM时，该金属也不会改变胰岛的葡萄糖氧化。相比之下，在存在1.25 mM Co²⁺的情况下，胰岛细胞对Ca的摄取可逆地减少（55%）。Co²⁺也使钙内流（在2.5分钟后测量）减少，且在更长的孵育时间后这种减少程度不变。结论是Co²⁺主要通过对β细胞中Ca内流的拮抗作用来抑制IRI释放。