2015-02-02 11:49:34木木醫師
Aminophyllin
Aminophylline is a nonselective adenosine receptor antagonist and is also a competitive nonselective phosphodiesterase (PDE) inhibitor.
Adenosine is an endogenous extracellular messenger that can regulate myocardial oxygen needs.
It acts through cellular surface receptors which effect intracellular signalling pathways to increase coronary artery blood flow, slow heart rate, block atrioventricular node conduction, suppress cardiac automaticity, and decrease β-adrenergic effects on contractility.
Aminophylline causes bronchodilation, diuresis, central nervous system and cardiac stimulation, and induces release of epinephrine from adrenal medulla cells.
Aminophylline causes bronchodilation, diuresis, central nervous system and cardiac stimulation, and induces release of epinephrine from adrenal medulla cells.
Adenosine also antagonizes chronotropic and ionotropic effects of circulating catecholamines. Overall, adenosine decreases the heart’s rate and force of contraction, which increases blood supply to the cardiac muscle. Given specific circumstances this mechanism (which is intended to protect the heart) may cause atropine-resistant refractory bradyasystole. Adenosine’s effects are concentration-dependent.
Adenosine’s receptors are competitively antagonized by methylxanthines such as aminophylline. Aminophylline competitively antagonizes the cardiac actions of adenosine at the cell surface receptors. Thus, it increases heart rate and contractility.
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