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首页> 外文期刊>Canadian Journal of Physiology and Pharmacology >Calcium-independent tacrine-induced relaxation of rat gastric corpus smooth muscles.
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Calcium-independent tacrine-induced relaxation of rat gastric corpus smooth muscles.

机译：钙非依赖性他克林诱导的大鼠胃体平滑肌松弛。

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摘要

Tacrine, a non-competitive reversible acetylcholinesterase and butyrylcholineserase inhibitor, caused a concentration-dependent tonic contraction of gastric smooth muscle preparations in the concentration range 1 x 10-7 mol/L - 1 x 10-5 mol/L, whereas concentrations higher than 2 x 10-5 mol/L induced a biphasic effect; a short-time contraction was followed by a prolonged relaxation. To shed some light on the mechanism underlying this untypical relaxation, the amplitude of mechanical reactions caused by tacrine were compared with those of tacrine in the presence of atropine, ipratropium, metrifonate, TTX, nifedipine, D-600, caffeine, apamin, and charybdotoxin. The results obtained revealed that the relaxation was neither cholinergic in nature, nor mediated by the influence of the drug on intramural neuronal structures. It was not influenced by processes inducing changes in cytosolic Ca2+ levels. This assumption was confirmed by experiments with permeabilized muscle preparations that were pre-contracted in a solution with pCa 5.5. Tacrine relaxed the smooth muscles in spite of the constant intracellular Ca2+ concentration resulting from the permeabilization. These findings argue that tacrine at concentrations higher than 2 x 10-5 mol/L has a desensitizing effect on the contractile apparatus of gastric corpus smooth muscle preparations towards Ca2+.
机译：他克林是一种非竞争性的可逆性乙酰胆碱酯酶和丁酰胆碱酯酶抑制剂，在1 x 10-7 mol / L-1 x 10-5 mol / L的浓度范围内引起胃平滑肌制剂的浓度依赖性强直收缩，而高于2 x 10-5 mol / L引起双相效应;短时收缩后长时间放松。为了弄清这种非典型松弛的机制，我们比较了在存在阿托品，异丙托溴铵，异丁苯甲酸盐，TTX，硝苯地平，D-600，咖啡因，罂粟碱和氨合毒素的情况下，他克林与他克林引起的机械反应的幅度。获得的结果表明，松弛本质上既不是胆碱能的，也不是药物对壁内神经元结构的影响所介导的。它不受诱导胞质Ca2 +水平变化的过程的影响。这一假设已通过在pCa 5.5溶液中预收缩的透化肌肉制剂的实验得到了证实。尽管透化作用使细胞内Ca2 +浓度恒定，但他克林仍可放松平滑肌。这些发现表明，他克林浓度高于2 x 10-5 mol / L时，对胃体平滑肌制剂对Ca2 +的收缩装置具有脱敏作用。

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