Dong Z, Xue C S
Department of Biochemical Pharmacology, Chongqing University of Medical Sciences, China.
Zhongguo Yao Li Xue Bao. 1994 Sep;15(5):452-5.
To elicit the correlation between the adrenergic transmitter release and calmodulin (CaM), the effect of verapamil on the free Ca2+ concentration was measured with fluorescence analysis and Ca(2+) Mg(2+)-ATPase activity in rat synaptosomes were studied. When stimulated with high-K+ or norepinephrine, the concentration of free Ca2+ in rat synaptosome was increased by verapamil 10, 50, and 100 mumol.L-1. But the free Ca2+ concentration in the resting synaptosome was reduced by verapamil. The activity of Ca(2+) Mg(2+)-ATPase in synaptosome was remarkably inhibited by verapamil in a dose-dependent manner. These results support our hypothesis that CaM not only acts directly on the vesicles to enhance the transmitter release, but also acts on the activity of Ca(2+) Mg(2+)-ATPase to reduce the free Ca2+ in the cytosol, and indirectly inhibited the transmitter release.
为了探究肾上腺素能递质释放与钙调蛋白（CaM）之间的相关性，采用荧光分析法测定了维拉帕米对游离Ca2+浓度的影响，并研究了大鼠突触体中Ca(2+) Mg(2+)-ATP酶活性。当用高钾或去甲肾上腺素刺激时，维拉帕米10、50和100 μmol·L-1可使大鼠突触体中游离Ca2+浓度升高。但维拉帕米可降低静息突触体中的游离Ca2+浓度。维拉帕米以剂量依赖性方式显著抑制突触体中Ca(2+) Mg(2+)-ATP酶的活性。这些结果支持了我们的假设，即CaM不仅直接作用于囊泡以增强递质释放，还作用于Ca(2+) Mg(2+)-ATP酶的活性以降低胞质溶胶中的游离Ca2+，并间接抑制递质释放。
