氨茶碱对腺苷负性变导效应的拮抗作用

本工作就氨茶碱对外源性腺苷负性变导效应的拮抗作用的确切性及特异性在全麻整体豚鼠身上做了研究。通过两个心房插管分别注入负性变导药(腺苷、乙酰胆碱、MnCl_2)及拮抗剂(氨茶碱、阿托品),从心电变化观察两组药剂间的相互作用。实验结果表明0.5mg/mL腺苷0.06～0.18mL能使全部豚鼠产生持续5～10秒以上的Ⅱ度房室传导阻滞,而30mg/mL氨荼减0.1～0.2mL可对所有豚鼠完全阻断上述量腺苷的负性变导效应。用适量乙酰胆碱(5μg/mL,0.06～0.20mL)及MnCl_2(10mg/mL,0.30～1.50mL)分别代替腺苷引起相似程度的房室传导阻滞,但都不能被氨茶碱所阻断。阿托品可封闭乙酰胆碱所致的传导阻滞,但对腺苷引起者毫无影响。本工作证实氨茶碱对腺苷的负性变导效应有确切、明显的拮抗作用,此拮抗作用在几种常用的负性变导性药物中表现出一定的特异性。

Specific Antagonistic Action of Aminophylline on the Negative Dromotropic Effect of Adenosine

The present Work deals with a study on the authenticity and specificity of the antagonistic action of aminophylline upon the negative dromotropic effect of exogenous adenosine in guinea pig. Negative dromotropic agents (adenosine, acetylcholine, MnCl₂) and their antagonists (aminophylline, atropine) were injected into the auricle successively through two pre-inser-ted cannulae to expose their hidden interrelaions in terms of electrocardio-graphic manifestations. Experimental results disclosed that 0.06～0.18mL of 0.5mg/mL adenosine could invariably give rise to a second-degree A-V block, whereas 0.1～0.2mL of 30mg/mL aminophylline was capable of antagonizing completely the nega-tive dromotropic effeet induced by adenosine at the same dosage mentioned above in almost all the guinea pigs tested. The substitution of acetylcholine (5μg/mL ,0.03～0.20mL)or manganese chloride (10mg/mL, 0.3～1.5mL)for adenosine could achieve A-V block likewise, but the negative dromotropic effect of ACh andMnCl₂ was characterized by its inability to be antagonized by aminophylline. Atropine was noted for its evoking a blockade on the negative dromotropic effect of acetylcholine, but failed to exert any inf-luence upon the A-V block caused by adenosine. This study confirmed the authenticity of the autagonistic action of aminophylline on the negative dromotropic effect of adenosine, and moreover, testified the specificity of the antagonistic interaction between aminophylline and adenosine as compared with other A-V block-inducing agents like acetylcholine and MnCl₂.