Lalanne C, Mironneau C, Mironneau J, Savineau J P
Br J Pharmacol. 1984 Feb;81(2):317-26. doi: 10.1111/j.1476-5381.1984.tb10081.x.
The effects of acetylcholine (ACh, 10(-4)M) and angiotensin II (Ang II, 10(-6) M) have been studied on the mechanical and electrical activities of rat myometrial strips perfused in Ca2+-free EGTA-containing solutions. Both ACh and Ang II produced transient contractions, the amplitude of which can be taken as a measurement of the amount of Ca2+ present in a drug-sensitive Ca2+ store. The degree of filling of this store depended on the external Ca2+ concentration, and on the presence of contractile responses during the Ca2+ loading period. The existence of two pathways (either direct or transcytoplasmic) is suggested for Ca2+ uptake into the internal Ca2+ store. The rate of filling of the Ca2+ store in 2.1 mM-Ca2+-containing solution was faster (time to half-maximal response, t 1/2 = 29 +/- 2.2 s, n = 4) than the rate of depletion in Ca2+-free solution (t 1/2 = 3 +/- 0.3 min, n = 3). The gradual depletion of this store was much slower at 18 degrees C than at 35 degrees C, and in the presence of vanadate which is known to inhibit Ca2+-ATPases. Methoxyverapamil (D600, 10(-6)-10(-5) M) had no appreciable effect on the direct Ca2+ uptake or on the release of Ca2+ from the store by ACh and Ang II. Mn2+ (10(-3) M) completely inhibited the direct pathway to the internal Ca2+ store and also reduced the release of Ca2+. ACh and Ang II induced repetitive depolarizations close to zero potential which did not parallel the transient contractions as a function of the time of perfusion in Ca2+-free solution. Applications of 2 mM EGTA, 135 mM K+ or Ca2+ antagonists which suppressed or reduced the drug-induced depolarizations did not affect appreciably the drug-induced contractions. These results suggest that myometrial cells have an intracellular Ca2+ store sensitive to different stimulus substances. This store is not affected by depolarization of the plasma membrane and is certainly different from that described in voltage-clamp experiments.
研究了乙酰胆碱（ACh，10⁻⁴M）和血管紧张素II（Ang II，10⁻⁶M）对在含无钙EGTA溶液中灌注的大鼠子宫肌条机械和电活动的影响。ACh和Ang II均产生短暂收缩，其幅度可作为药物敏感钙库中钙含量的一种测量指标。该钙库的充盈程度取决于外部钙浓度以及钙加载期的收缩反应情况。提示存在两条钙摄取进入内部钙库的途径（直接或经细胞质）。在含2.1 mM钙的溶液中钙库的充盈速率更快（达到最大反应一半的时间，t 1/2 = 29 ± 2.2秒，n = 4），而在无钙溶液中的耗竭速率（t 1/2 = 3 ± 0.3分钟，n = 3）较慢。在18℃时该钙库的逐渐耗竭比在35℃时慢得多，并且在已知可抑制钙ATP酶的钒酸盐存在时也是如此。甲氧基维拉帕米（D600，10⁻⁶ - 10⁻⁵M）对直接钙摄取或ACh和Ang II从钙库中释放钙没有明显影响。Mn²⁺（10⁻³M）完全抑制了进入内部钙库的直接途径，也减少了钙的释放。ACh和Ang II在无钙溶液中诱导接近零电位的重复去极化，其与短暂收缩在灌注时间上的变化并不平行。应用2 mM EGTA、135 mM K⁺或抑制或减少药物诱导去极化的钙拮抗剂对药物诱导的收缩没有明显影响。这些结果表明子宫肌层细胞具有对不同刺激物质敏感的细胞内钙库。该钙库不受质膜去极化的影响，并且肯定与电压钳实验中描述的不同。
