Xuan B, Zhang M Y, Liu F, Xiao J G
Department of Pharmacology, Nanjing Medical University, China.
J Ocul Pharmacol Ther. 1996 Summer;12(2):151-8. doi: 10.1089/jop.1996.12.151.
The effect of tetrandrine (Tet) on the changes of intracellular free Ca2+ concentration ([Ca2+]i) induced by high concentration of K+ and norepinephrine is dissociated rabbit retina cells were studied. The changes of [Ca2+]i were reflected by the fluorescent indicator, Fura-2/AM, employed. The resting [Ca2+]i was 223 +/- 27 nM in Hank's solution containing 1.3 mM Ca2+. Tet at 30 microM did not affect the resting [Ca2+]i when the extracellular Ca2+ concentration was in the range of 0-2 mM. Tet at 1-100 microM suppressed the [Ca2+]i elevation induced by high concentration of K+ in a concentration-dependent manner. When the concentration of K+ was 50 mM IC50 for Tet was 10.9 microM. Although Tet at high concentration (30 microM) suppressed the [Ca2+]i increases induced by norepinephrine (0.1-100 nM) in the presence of Ca2+ at 1.3 mM, failed to do the same at lower concentration of Tet (1-10 microM), however, Tet at 30 microM did not effect the release of intracellular Ca2+ stored in the sarcoplasmic reticulum in the Ca(2+)-free Hank's solution. These results indicate that Tet is able to block Ca2+ influx from extracellular site via voltage-sensitive ionic channels and at high concentration via receptor-operated ionic channels in retina cells.
研究了粉防己碱（Tet）对高浓度钾离子和去甲肾上腺素诱导的兔视网膜细胞内游离钙离子浓度（[Ca2+]i）变化的影响。[Ca2+]i的变化通过使用的荧光指示剂Fura-2/AM来反映。在含有1.3 mM钙离子的Hank's溶液中，静息[Ca2+]i为223±27 nM。当细胞外钙离子浓度在0-2 mM范围内时，30 μM的粉防己碱不影响静息[Ca2+]i。1-100 μM的粉防己碱以浓度依赖的方式抑制高浓度钾离子诱导的[Ca2+]i升高。当钾离子浓度为50 mM时，粉防己碱的IC50为10.9 μM。虽然在1.3 mM钙离子存在的情况下，高浓度（30 μM）的粉防己碱抑制去甲肾上腺素（0.1-100 nM）诱导的[Ca2+]i增加，但在较低浓度的粉防己碱（1-10 μM）时则不能，然而，30 μM的粉防己碱在无钙的Hank's溶液中对肌浆网中储存的细胞内钙离子释放没有影响。这些结果表明，粉防己碱能够通过电压敏感离子通道阻断细胞外钙离子内流，在视网膜细胞中高浓度时还能通过受体操纵离子通道阻断钙离子内流。
