title: Respiratory and cardiovascular effects of 3-methylxanthine, a metabolite of theophylline.
abstract: The effects of 3-methylxanthine (3-MX), a major metabolite of theophylline in man, were studied and compared with those of theophylline in isolated preparations of human and guinea-pig airways, isolated guinea-pig hearts, and in anaesthetized cats. 3-MX was pharmacologically active, producing effects similar to those of theophylline. The guinea-pig and human airways preparations were relaxed; the rate and force of contraction of guinea-pig hearts were increased. In anaesthetized cats, 3-MX decreased the respiratory overflow and arterial blood pressure, and increased the heart rate. Theophylline was always more potent (between 1 and 5 times) than 3-MX. It is suggested that 3-MX may contribute to the effects of theophylline during long-term treatment.
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002319:Cardiovascular System / Q000187:drug effects*; D002415:Cats; D004341:Drug Evaluation; D004353:Drug Evaluation, Preclinical; D004639:Emetics; D005260:Female; D006168:Guinea Pigs; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008168:Lung / Q000187:drug effects; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D012119:Respiration / Q000187:drug effects*; D013806:Theophylline / Q000378:metabolism / Q000494:pharmacology* / Q000652:urine; D013997:Time Factors; D014132:Trachea / Q000187:drug effects; D014970:Xanthines / Q000378:metabolism / Q000494:pharmacology* / Q000652:urine
chemical_list: D004639:Emetics; D014970:Xanthines; D013806:Theophylline