Negative inotropic effects of caffeine related to leak of Ca2+ from the sarcoplasmic reticulum.

Abstract

Caffeine has been reported to have either a positive or a negative inotropic effect on cardiac muscle, and it is not known what circumstances are necessary for each of these effects. In this study, rat atria were exposed to caffeine (1–5) mM with regular stimulation at 0.1 – 3 Hz. Postrest contractions were also observed to determine if inhibition of contractions was always seen when stimulation was interrupted (Endoh and Iijima, 1981). As expected, addition of caffeine to the superfusate resulted in a transient positive inotropic response, when stimulation was 0.5 or 2.0 Hz. In contrast with this, when stimulation was 0.1 Hz, there was only a negative inotropic response. This decrease in developed tension was greater with 1 mM than with 5 mM caffeine, (see Table 1).KeywordsSarcoplasmic ReticulumStimulation FrequencyNegative Inotropic EffectInotropic ResponseDevelop TensionThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.