用Fura-2测定突触体内游离Ca^(2+)浓度及Ca^(2+)通道激动剂和阻断剂的影响

ESTIMATION OF FREE CALCIUM LEVEL WITHIN SYNAPTOSOMES BY USING FURA—2 AND THE EFFECT OF CALCIUM CHANNEL AGONIST AND ANTAGONIST

用Fura-2测定大鼠突触体内游离Ca^(2+)浓度,探讨Ca^(2+)通道激动剂和阻断剂对突触体内钙浓度的影响。测得突触体内Ca^(2+)浓度为200～400 nmol/L。观察了不同浓度KCl,CaCl_2,NMDA和谷氨酸对突触体内Ca^(2+)增加的影响以及维拉帕米及MgCl_2对KCl和NMDA引起钙内流的阻断作用。本实验提供一个研究突触体内Ca^(2+)变化的准确而稳定的方法,并对测定中几个影响因素加以讨论。

The cytosolic free calcium concentration [Ca^(2+)]i in synaptosomes was determined with the fluorescent indicator fura-2, the effects of calcium channel agonist and antagonist on intracellular Ca^(2+) level were studied. The cytosolic ionized calcium concentrations in resting status were between 200 nmol/L and 400 nmol/L. Cytosolic Ca^(2+) was elevated following increases in Ca^(2+) concentration in the medium, plasma membrane depolarizations induced by KC1, and the addition of glutamate and NMDA. On the other hand, the increase of cytosolic Ca^(2+) induced by KCI was decreased by verapamil and that induced by NMDA was decreased by MgCl_2.A few critical problems in [Ca^(2+)]i detection were also discussed.