Polanin A, McNeill J H
Can J Physiol Pharmacol. 1981 Jan;59(1):25-30. doi: 10.1139/y81-005.
Rabbit isolated right and left atria were exposed to theophylline and to selected doses of histamine agonists. Right atrial rate and left atrial tension were increased by theophylline (3 x 10(-4) M), the H1 agonist 2-pyridylethylamine (PEA) (1 x 10(-4) M), and the H2 agonists 4-methylhistamine (1 x 10(-4) M) and impromidine (1 x 10(-8) M). In the right atria the combined effect of theophylline (3 x 10(-4) M) and any of the histamine agonists was greater than the response to either agonist alone. However, the combined effects were not significantly greater than the sum of the individual right atrial responses. In the left atria the combined effect of theophylline (3 x 10(-4) M) with any one of the histamine agonists was not only greater than the response to either agonist alone but was also significantly greater than the sum of the individual responses. The potentiation of the left atrial response to the H2 agonists by theophylline was significantly decreased by the H2 antagonist cimetidine (1 x 10(-5) M). However, the potentiation of the left atrial response to the H1 agonist (PEA) by theophylline was not significantly altered by the H1 antagonist promethazine (2 x 10(-6) M). Reports that the cardiac effects of H1 and H2 receptor agonists are potentiated by phosphodiesterase inhibitors such as theophylline as a result of increased cyclic AMP levels are not supported by the present study.
将兔的离体右心房和左心房分别暴露于茶碱和选定剂量的组胺激动剂中。茶碱（3×10⁻⁴ M）、H1激动剂2-吡啶乙胺（PEA）（1×10⁻⁴ M）、H2激动剂4-甲基组胺（1×10⁻⁴ M）和英普咪定（1×10⁻⁸ M）可使右心房率和左心房张力增加。在右心房中，茶碱（3×10⁻⁴ M）与任何一种组胺激动剂的联合作用均大于单独使用任何一种激动剂的反应。然而，联合作用并不显著大于右心房单独反应的总和。在左心房中，茶碱（3×10⁻⁴ M）与任何一种组胺激动剂的联合作用不仅大于单独使用任何一种激动剂的反应，而且显著大于单独反应的总和。H2拮抗剂西咪替丁（1×10⁻⁵ M）可显著降低茶碱对H2激动剂引起的左心房反应的增强作用。然而，H1拮抗剂异丙嗪（2×10⁻⁶ M）对茶碱增强左心房对H1激动剂（PEA）反应的作用无显著影响。本研究不支持有关磷酸二酯酶抑制剂如茶碱因环磷酸腺苷水平升高而增强H1和H2受体激动剂心脏效应的报道。
