Oral theophylline in chronic heart failure

Effects of enprofylline, theophylline and terbutaline on second inward currents in papillary muscles from ferrets and guinea-pigs

In ferret and guinea pig papillary muscles enprofylline (10 microM-10 mM) and theophylline (0.1-2 mM) alone or in combination with terbutaline (0.05 microM-0.1 microM) decreased the action potential duration and increased the plateau height, increased the peak force of contraction and facilitated the depolarization-induced automaticity. In voltage clamp, the xanthines alone or in combination with terbutaline increased second inward currents, ICa,f and ICa,2, but had relatively less effect on the time-dependent outward current. No qualitative differences between enprofylline and theophylline could be detected but the former was about 5 times more potent in increasing ICa,f. In clinically relevant concentrations, enprofylline and theophylline alone, or in combination with terbutaline caused a small (2-5%) shortening of the action potential.

Bronchodilating plasma concentrations of enprofylline and theophylline have minor cardiovascular effects in man

The cardiovascular effects with bronchodilating plasma concentration of theophylline (3.8-12.6 mg/l) and enprofylline (0.8-3.0 mg/l) were studied in six healthy male subjects by means of non-invasive procedures. With these plasma concentrations only minor effects were noted with regard to heart rate, blood pressure and systolic time intervals. However, both xanthines seem to have a vasodilating ability and a weak positive inotropic effect on the heart.