粉防己碱对培养乳牛基底动脉平滑肌细胞内游离钙浓度的影响

目的：研究粉防己碱对培养乳牛基底动脉平滑肌细胞游离钙浓度（Ca^2 ]i)的影响。方法：利用AR－CM－MIC阳离子测定系统,采用Fura 2-AM为指示剂,测量单个细胞内Ca^2 ]i。结果：粉防己碱10－100μmol/L对培养乳牛基底动脉平滑肌细胞静息Ca^2 ]i无明显影响。在细胞外钙为1．3mmol/L,粉防己碱可浓度依赖性地抑制KC1引起Ca^2 ]i的升高。咖啡因10mmol/L可诱导一次Ca^2 ]i瞬间快速升高,随后自发回复到静息水平,粉防己碱10和30μmol/L对咖啡因诱导的Ca^2 ]i瞬间升高没有作用,但高浓度（100μmol/L）粉防己碱抑制了Ca^2 ]i瞬间升高。在细胞外钙为1.3mmol/L,苯肾上腺素10μmol/L可引起双相Ca^2 ]i变化,包括快速升高相和持续升高相。在细胞外钙为零,苯肾上腺素仅引起Ca^2 ]i的快速升高相。粉防己碱可浓度依赖性地抑制苯肾上腺素引起Ca^2 ]i快速升高相。结论：在培养乳牛基底动脉平滑肌细胞,粉防己碱可能通过影响电压依赖性和苯肾上腺素受体介导的钙通道而抑制钙内流。高浓度粉防己碱也可能影响肌浆网钙释放或钙摄取。

Effect of tetrandrine on free intracellular calcium in cultured calf basilar artery smooth muscle cells

AIM: To study the effects of tetrandrine (Tet) on extracellular Ca2+ influx and intracellular Ca2+ release in cultured calf basilar artery smooth muscle cells. METHODS: Free intracellular calcium was examined by a system of measurement of AR-CM-MIC, using Fura 2-AM as a fluorescent indicator. RESULTS: In the presence of extracellular Ca2+ 1.3 mmol/L, no significant effect of Tet on resting Ca2+]i was found. KCl 20, 40, and 60 mmol/L triggered a sustained rise in Ca2+]i, pretreatment with Tet inhibited the elevation of Ca2+]i induced by KCl in concentration-dependent manner, Tet at high concentration (100 micromol/L) almost abolished the rise of Ca2+]i evoked by KCl. Caffeine 10 mmol/L only produced a transient increase of Ca2+]i, which spontaneously declined back to resting levels. Tet 10-30 micromol/L had no effect on caffeine-induced Ca2+]i transient peak. Tet at high concentration (100 micromol/L), however, reduced the Ca2+]i transient peak induced by caffeine. Phenylephrine (PE) 10 mmol/L produced a rapid transient peak and a distinct sustained elevation in Ca2+]i in the presence of extracellular Ca2+. In the absence of extracellular Ca2+ containing egtazic acid (EGTA), PE only produced a rapid transient peak in Ca2+]i. Pretreatment of Tet (10-100 micromol/L) inhibited the sustained elevation in Ca2+]i induced by PE in a concentration-dependent manner. However, only 100 micromol/L of Tet inhibited the transient peak in Ca2+]i induced by PE both in the presence of extracellular Ca2+ 1.3 mmol/L and in the absence of extracellular Ca2+ containing EGTA. CONCLUSION: Tet inhibited the Ca2+ influx from the extracellular site via voltage-activated Ca2+ channel and PE-receptor-operated Ca2+ channel. At a high concentration, Tet may inhibit the Ca2+ release from sarcoplasmic reticulum (SR) or refilling of intracellular calcium store in cerebral artery smooth muscle cells.