CHARACTERIZATION OF INCREASED CA-2+ EFFLUX BY QUERCETIN FROM THE SARCOPLASMIC-RETICULUM IN FROG SKINNED SKELETAL-MUSCLE FIBERS
CHARACTERIZATION OF INCREASED CA-2+ EFFLUX BY QUERCETIN FROM THE SARCOPLASMIC-RETICULUM IN FROG SKINNED SKELETAL-MUSCLE FIBERS
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DOI：
10.1007/bf01753415
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发表时间：
1986-04-01
影响因子：
2.7
通讯作者：
OGAWA, Y
中科院分区：
文献类型：
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作者：
KUREBAYASHI, N;OGAWA, Y
为了进一步阐明槲皮素的钙释放作用的特点，我们研究了槲皮素对钙从肌浆网流出的影响，没有钙摄取活性，在高浓度（10 mM EDTA）的Ca 2+缓冲液的存在下，通过省略ATP，使用机械剥皮的青蛙骨骼肌纤维。槲皮素在Ca 2+存在下增加Ca释放速率，并将Ca 2+浓度与Ca释放速率之间的关系转移到较低的Ca 2+浓度范围。AMP增强槲皮素的作用。Mg ~（2+）和普鲁卡因降低了槲皮素存在下的钙释放速率。这些发现表明槲皮素与咖啡因非常相似;事实上，实验证实槲皮素与咖啡因共享作用位点。然而，随后的研究结果表明，药物诱导的Ca释放的机制并不像预期的那样简单，咖啡因可能会增加“Ca 2+诱导的Ca释放”机制对Ca 2+的亲和力，并且药物、Ca 2+和核苷酸以更复杂的方式相互作用以打开Ca释放的大门。在10 mM EGTA存在下，如果存在足够量的AMP，槲皮素也在几乎不存在Ca 2+的情况下引起Ca释放，并且在1.55 μ M Ca 2+存在下的Ca释放速率显示出在有和没有槲皮素的情况下对AMP浓度的不同依赖性。为了消除槲皮素释放的Ca，在AMP存在下比在AMP不存在下需要更高浓度的Mg 2+。
To clarify further the characteristics of the Ca-releasing action of quercetin, we examined the effect of quercetin on Ca2+ efflux from the sarcoplasmic reticulum without Ca uptake activity by omission of ATP in the presence of high concentration (10 mM EDTA) of Ca2+ buffer, using mechanically skinned fibres from frog skeletal muscles. Quercetin increases the rate of Ca release in the presence of Ca2+ and shifts the relationship between Ca2+ concentration and the rate of Ca release to a lower range of Ca2+ concentrations. AMP potentiates the effect of quercetin. Mg2+ and procaine decrease the rate of Ca release in the presence of quercetin. These findings indicate that quercetin is very similar to caffeine; in fact, experiments confirmed that quercetin shares the site(s) of action with caffeine. Subsequent findings, however, suggest that the mechanism of the drug-induced Ca release is not as simple as expected with caffeine which may increase the affinity for Ca2+ of the ''Ca2+-induced Ca-release'' mechanism, and that drugs, Ca2+ and nucleotide interact with one another in a more complex way to open the gate for Ca release. In the presence of 10 mM EGTA quercetin also causes Ca release in the virtual absence of Ca2+ if a sufficient amount of AMP is present, and the rate of Ca release in the presence of 1.55 .mu.M Ca2+ showed different dependence on AMP concentration with and without quercetin. A higher concentration of Mg2+ is required in the presence of AMP than in the absence of AMP in order to eliminate Ca release by quercetin.