Energetic effects of caffeine in face retarded Na+/Ca2+ exchange in isolated, arrested guinea pig hearts

Examination of the influence of caffeine on the rate of oxygen consumption V(O2) and left ventricular diastolic pressure development of isolated, KCl-arrested, guinea pig hearts reveals the absence of caffeine influence on both V(O2) and left ventricular pressure development. However, caffeine introduction leads to a significant increase in V(O2), on inhibiting Ca2+ extrusion through the Na+/Ca2+ exchanges. Na+/Ca2+ exchange regulates the energetic effects of caffeine on the pharmacological activation of the sarcoplasmic reticulum Ca2+ release channel.