左旋千金藤定碱对培养牛主动脉血管平滑肌细胞胞内游离Ca~(2+)的影响

目的：研究左旋千金藤定碱（ｌ－ｓｔｅｐｈｏｌｉｄｉｎｅ，ＳＰＤ）对血管平滑肌的作用。方法：采用Ｆｕｒａ－２和ＡＲ－ＣＭ－ＭＩＣ阳离子测定系统测定培养牛主动脉血管平滑肌细胞内游离钙。结果：ＳＰＤ１～１００μｍｏｌ·Ｌ－１不影响静息［Ｃａ２＋］ｉ，但可剂量依赖地抑制高Ｋ＋引起的［Ｃａ２＋］ｉ增高，其ＩＣ５０为３９．６（９５％可信限２３．４～６７．１）μｍｏｌ·Ｌ－１，但其作用弱于尼群地平；ＳＰＤ１～１００μｍｏｌ·Ｌ－１对去甲肾上腺素、血管紧张素Ⅱ、５－ＨＴ、ＡＴＰ引起的［Ｃａ２＋］ｉ增高也有明显的抑制作用；高浓度ＳＰＤ对无外钙时去甲肾上腺素引起的［Ｃａ２＋］ｉ增高也有一定的抑制作用。结论：左旋千金藤定碱对培养血管平滑肌细胞电压依赖性钙通道和受体调控性钙通道均有抑制作用；其对电压依赖性钙通道的抑制作用弱于尼群地平。

Effects of stepholidine on cytosolic free calcium in cultured bovine aortic smooth muscle cells

AIM: To study the effects of stepholidine (SPD) on intracellular Ca 2+ in cultured vascular smooth muscle cells (VSMC). METHODS: The cytosolic free calcium ([Ca 2+ ] i) in cultured bovine aortic VSMC were examined using Fura 2/AM and AR CM MIC cation measurement system. RESULTS: SPD (1～100 μmol·L -1 ) had no effects on the resting [Ca 2+ ] i , but inhibited the elevation of [Ca 2+ ] i induced by KCl dose dependantly, the IC 50 value of SPD being 39 6(95% confidence limits 23 4～67 1) μmol·L -1 , Its effects were weaker than those of Nit; SPD (1～100 μmol·L -1 ) was also shown to inhibit the elevation of [Ca 2+ ] i induced by NE, Ang Ⅱ,5 HT and ATP in the prescence of extracellular Ca 2+ . In the absence of extracellular Ca 2+ , SPD 30～100 μmol·L -1 also showed some blocking effects on NE induced elevation of [Ca 2+ ] i. CONCLUSIONS: SPD might have the inhibitory effects on both VOC and ROC in bovine aortic smooth muscle cells, but its effects on VOC were weaker than those of Nit.