Narita S, Watanabe M
J Pharmacobiodyn. 1982 Apr;5(4):285-94. doi: 10.1248/bpb1978.5.285.
Effects of calcium blockers and Mn on the mechanical response of the isolated rat iris sphincter and the dilator were investigated. The contraction of the sphincter in response to acetylcholine, the contraction of the dilator in response to norepinephrine and the relaxation-contraction of the dilator in response to acetylcholine and also resting tone of dilator muscle were strongly dependent to external Ca concentration to different extents, while these responses and the tone were scarcely affected by calcium blockers, D-600, diltiazem (all 1 micro M), or nitroprusside Na (0.1 nM). In depolarized sphincter muscle (in the presence of atropine and phentolamine), the contraction induced by externally added Ca was reduced moderately by the Ca-blockers but this effect was far weaker than that expected from their effect on other smooth muscles. Mn (0.3 mM) moderately reduced the calcium contraction of depolarized sphincter. In depolarized dilator muscle, the contraction induced by Ca was not inhibited effectively by any of these Ca blockers but was moderately reduced by Mn. It is suggested that the rat iris muscles are resistant to "organic Ca-blockers" but sensitive to Mn, an "inorganic Ca-blocker".
研究了钙通道阻滞剂和锰对离体大鼠虹膜括约肌和瞳孔开大肌机械反应的影响。括约肌对乙酰胆碱的收缩反应、瞳孔开大肌对去甲肾上腺素的收缩反应以及瞳孔开大肌对乙酰胆碱的舒张 - 收缩反应，还有瞳孔开大肌的静息张力在不同程度上都强烈依赖于细胞外钙浓度，而这些反应和张力几乎不受钙通道阻滞剂、D - 600、地尔硫䓬（均为1微摩尔）或硝普钠钠（0.1纳摩尔）的影响。在去极化的括约肌肌肉中（在阿托品和酚妥拉明存在的情况下），外源性添加钙所诱导的收缩被钙通道阻滞剂适度减弱，但这种作用远弱于它们对其他平滑肌的作用。锰（0.3毫摩尔）适度减弱了去极化括约肌的钙收缩。在去极化的瞳孔开大肌中，钙所诱导的收缩并未被任何一种钙通道阻滞剂有效抑制，但被锰适度减弱。提示大鼠虹膜肌肉对“有机钙通道阻滞剂”有抗性，但对“无机钙通道阻滞剂”锰敏感。
