豚鼠输精管暴露于哇巴因期间钙、锶和钡诱导的去甲肾上腺素分泌量

Noradrenaline output induced by calcium, strontium and barium during exposure of guinea-pig vas deferens to ouabain.

作者信息

Nakazato Y, Ito S, Ohga A

出版信息

Eur J Pharmacol. 1980 Dec 5;68(3):327-37. doi: 10.1016/0014-2999(80)90530-0.

PMID:7202496

Abstract

The effects of tetrodotoxin (TTX, 5 x 10(-7) g/ml) and excess Mg2+ (20 mM) on the noradrenaline output induced by the addition of 2.5 mM of Ca2+, Sr2+ and Ba2+ during exposure to ouabain were observed using isolated guinea-pig vas deferens. Excess Mg2+ reduced the noradrenaline output induced by Ba2+ or Sr2+, but not that induced by Ca2+, regardless of whether it was added before or after the start of exposure to ouabain. In contrast, when added before the exposure to ouabain, TTX was most effective in retarding and in decreasing the noradrenaline output induced by Ca2+, La3+ (0.25 mM) inhibited, and transmural electrical stimulation potentiated the Ca2+-induced response during exposure to ouabain. These results confirmed that Ca2+-induced response during exposure to ouabain in mainly mediated by a Na+-dependent Ca2+ influx system. In contrast, Sr2+ and Ba2+ may enter into adrenergic nerve terminals mainly through depolarization and induce the output of noradrenaline when the Na+-K+ pump is inhibited.

摘要

利用离体豚鼠输精管，观察了河豚毒素（TTX，5×10⁻⁷g/ml）和过量镁离子（20 mM）对哇巴因作用期间添加2.5 mM钙离子、锶离子和钡离子所诱导的去甲肾上腺素释放的影响。无论在开始暴露于哇巴因之前还是之后添加，过量镁离子均可降低由钡离子或锶离子诱导的去甲肾上腺素释放，但对钙离子诱导的释放无影响。相反，在暴露于哇巴因之前添加时，TTX对延缓和降低钙离子诱导的去甲肾上腺素释放最为有效，镧离子（0.25 mM）可抑制，而跨膜电刺激可增强哇巴因作用期间钙离子诱导的反应。这些结果证实，哇巴因作用期间钙离子诱导的反应主要由钠依赖性钙离子内流系统介导。相比之下，锶离子和钡离子可能主要通过去极化进入肾上腺素能神经末梢，并在钠钾泵受抑制时诱导去甲肾上腺素释放。