Jatrophone (JAT), a diterpene isolated from the plant Jatropha elliptica (1-300 microM), caused a concentration-dependent relaxation effect against acetylcholine (Ach)-oxytocin (Ot)- and KCl-induced uterine sustained contraction. The relative potency order was: Ach greater than Ot greater than KCl. 2. The relaxant effect of JAT was not modified by phorbol ester, forskolin, MIX, TMB-8 and W-7. The increase concentration of calcium (0.2-2 mM) in the medium did not reverse the inhibitory effect caused by JAT. 3. Pre-incubation of the preparations with JAT (16-32 microM) for 20 min, caused a concentration-dependent inhibition of KCl-induced contractile response. At 30 microM, JAT inhibited in an apparently non-competitive manner CaCl2-induced contraction in K+-depolarized preparations. High concentrations of JAT (100 microM) also caused a time-dependent relaxation in CaCl2-induced sustained uterine contraction (T1/2 = approx. 15 min). 4. JAT (30 microM) inhibited the dihydropyridine calcium channel agonist Bay K 8644-induced uterine contraction in an apparently non-competitive fashion, while verapamil (0.1 microM) caused an rightward displacement of Bay K 8644 contraction and marked inhibition of the maximal response.
摘要
麻风树素（JAT）是从椭圆叶麻风树中分离出的一种二萜（1 - 300微摩尔），对乙酰胆碱（Ach）、催产素（Ot）和氯化钾诱导的子宫持续性收缩具有浓度依赖性的松弛作用。相对效力顺序为：Ach＞Ot＞KCl。2. 佛波酯、福斯高林、MIX、TMB - 8和W - 7不改变JAT的松弛作用。培养基中钙浓度增加（0.2 - 2毫摩尔）不会逆转JAT引起的抑制作用。3. 将制剂与JAT（16 - 32微摩尔）预孵育20分钟，会导致对氯化钾诱导的收缩反应产生浓度依赖性抑制。在30微摩尔时，JAT以明显非竞争性方式抑制钾离子去极化制剂中氯化钙诱导的收缩。高浓度的JAT（100微摩尔）也会导致氯化钙诱导的子宫持续性收缩出现时间依赖性松弛（半衰期约为15分钟）。4. JAT（30微摩尔）以明显非竞争性方式抑制二氢吡啶钙通道激动剂Bay K 8644诱导的子宫收缩，而维拉帕米（0.1微摩尔）使Bay K 8644收缩向右移位并显著抑制最大反应。
