Cardiovascular system SOCE as a determinant of cardiac pacemaker activity

Abstract

Store-operated calcium entry (SOCE) has been found in both inexcitable and excitable cells though its function is often unclear. Recent evidence suggests that cardiac pacemaker cells have SOCE and that the associated current may contribute to pacemaker function. In this chapter we review the function of pacemaker cells and consider the evidence that they express SOCE. To explore the possible contributions of SOCE to pacemaker function we have used a computer model, which includes the known pacemaker currents together with Ca 2+ handling functions. We added a SOCE current to this model and explore how this modifies firing rate. The results show that SOCE current can contribute to pacemaker activity and can either accelerate or slow the heart rate depending on the time constant of activation of the current. In order for the modeling to fit our experimental data, the time constant of activation of SOCE currents after SR Ca 2+ depletion needed to be 1 s or greater.