钙反转：用乙二醇双四乙酸（EGTA）研究表明，子宫平滑肌中低微摩尔浓度钙离子的抑制位点在细胞内的定位。

Calcium reversal: intracellular localization of site of inhibition by a submicromolar concentration of Ca ion in uterine smooth muscle shown by studies with EGTA.

作者信息

Sakai K, Yamagishi T, Higuchi-Nakamura K, Uchida M K

出版信息

Gen Pharmacol. 1984;15(6):549-52. doi: 10.1016/0306-3623(84)90214-3.

Abstract

The effect of EGTA on the decay of oxytocin-induced contraction of rat uterine smooth muscle in Ca-free solution was studied to clarify the mechanism of inhibition by low concentration of Ca ion (10(-8)-10(-7) M) of the contraction, i.e. "Ca reversal". The decay was significantly greater in the absence than in the presence of EGTA (0.2 mM). But the effect was not rapid. The concentration of contaminating Ca ion was ca. 10(-5) M and the concentration of free Ca ion was ca. 10(-7) M in the presence of EGTA (0.2 mM). The difference in the decay rate in the absence and presence of EGTA was found to be due to the difference of concentration of free Ca ion, the contaminating Ca ion causing inhibition (Ca reversal). The slow appearance of inhibition in the absence of EGTA was due to the slow influx of Ca ion into the cell. It is concluded that the "Site of Ca reversal", the site of this inhibition, is intracellular and has very high affinity for Ca ion.

摘要

研究了乙二醇双（2-氨基乙基醚）四乙酸（EGTA）对无钙溶液中催产素诱导的大鼠子宫平滑肌收缩衰减的影响，以阐明低浓度钙离子（10⁻⁸ - 10⁻⁷ M）对收缩的抑制机制，即“钙逆转”。在无EGTA（0.2 mM）时的衰减明显大于有EGTA时。但这种作用并不迅速。在存在EGTA（0.2 mM）的情况下，污染钙离子的浓度约为10⁻⁵ M，游离钙离子的浓度约为10⁻⁷ M。发现在无EGTA和有EGTA时衰减速率的差异是由于游离钙离子浓度的差异，污染钙离子导致抑制（钙逆转）。在无EGTA时抑制作用出现缓慢是由于钙离子缓慢流入细胞。结论是，这种抑制作用的“钙逆转位点”在细胞内，并且对钙离子具有非常高的亲和力。