Communication Between the Plasma Membrane and Cytosolic Cardiac Pacemakers: A Role for Melatonin?

We review here briefly the essentials of vertebrate cardiac pacemaking system consisting populations ion channels that drive heartbeat. In addition to sarcolemmal system, there is a second channel-based oscillator centrally reciprocating Ca2+ flow between sarcoplasmic reticulum and cytosol regulated by release through ryanodine receptors active return Sarcoplasmic/Endoplasmic Reticulum Calcium ATPase. considerable similarity fly heart pacemakers. our work with Drosophila, we have shown melatonin capable increasing rhythmicity remarkable level. This true even in flies bearing mutations severely damage central plasma membrane pacemaker. evidence showing gene encoding ATPase severe effects on function. present further from has only modest effect reversing these defects. hypothesized acts altering relationship cytosolic oscillators cite previous findings as provocative this regard.