Hoy A W, Cameron A M
Eur J Pharmacol. 1986 Sep 23;129(1-2):105-12. doi: 10.1016/0014-2999(86)90341-9.
Stonefish skin secretion contains a smooth muscle relaxant, synancein II, that selectively inhibits tonic responses of KCl-induced contractions of the guinea-pig vas deferens. Synancein II (5-50 micrograms/ml) and nifedipine (10(-8)-10(-7) M) reduced tonic responses equally. Over these concentrations, synancein II inhibited phasic responses more than did nifedipine. Rapid inhibition of phasic responses by synancein II (low concentrations) but its inability to block this response at high concentrations suggests that more than one extracellular and/or intracellular Ca2+ source may contribute to the generation of the phasic response. Some calcium antagonists selectively inhibit tonic responses induced by KCl in many different organs, whilst others inhibit phasic responses. Whereas we previously reported that synancein II selectively inhibits phasic rather than tonic responses in the guinea-pig ileum, the present results reveals a reversal of this selectivity.
石鱼皮肤分泌物含有一种平滑肌松弛剂，即石鱼毒素II，它能选择性抑制氯化钾诱导的豚鼠输精管收缩的强直反应。石鱼毒素II（5 - 50微克/毫升）和硝苯地平（10^(-8) - 10^(-7) 摩尔）对强直反应的抑制作用相当。在这些浓度范围内，石鱼毒素II对相性反应的抑制作用比硝苯地平更强。石鱼毒素II（低浓度）能快速抑制相性反应，但高浓度时无法阻断该反应，这表明可能有不止一种细胞外和/或细胞内钙源参与相性反应的产生。一些钙拮抗剂在许多不同器官中选择性抑制氯化钾诱导的强直反应，而另一些则抑制相性反应。虽然我们之前报道石鱼毒素II在豚鼠回肠中选择性抑制相性而非强直反应，但目前的结果显示这种选择性发生了逆转。
