Cardiovascular effects of theophylline

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Abstract
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 µg/ml in the absence of beta blockade, 16.1±1.7 µg/ml during metoprolol, and 15.1±1.6 µg/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 (p2I. Theophylline has a mild inotropic effect in healthy subjects. This effect is prevented by pretreatment with beta-adrenergic antagonists.