Cardiovascular effects of theophylline. Partial attenuation by beta-blockade.
The effects of theophylline upon cardiovascular function were studied in 8 male subjects, aged 22-33 years, before and during concomitant administration of metoprolol (50 mg every 6 h) and propranolol (40 mg every 6 h). Theophylline, as aminophylline (6.7-7.3 mg/kg) was given over 30 min. The theophylline level five minutes after completion of the aminophylline infusion was 15.9 +/- 1.8 micrograms/ml in the absence of beta blockade, 16.1 +/- 1.7 micrograms/ml during metoprolol, and 15.1 +/- 1.6 micrograms/ml during propranolol. Theophylline produced a 7% increase in mean arterial pressure which was not attenuated by either metoprolol or propranolol. Heart rate was not changed by theophylline. The QS2 Index (QS2I), a sensitive indicator of inotropism, was shortened from 488 +/- 16 to 476 +/- 16 msec (p less than 0.01) by theophylline alone. After administration of metoprolol or propranolol, theophylline produced no shortening of the QS2I. Theophylline has a mild inotropic effect in healthy subjects. This effect is prevented by pretreatment with beta-adrenergic antagonists.
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D002319:Cardiovascular System / Q000187:drug effects*; D003971:Diastole / Q000187:drug effects; D004562:Electrocardiography; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D013806:Theophylline / Q000494:pharmacology*
D000319:Adrenergic beta-Antagonists; D013806:Theophylline