Sarcoplasmic Reticulum Ca ²⁺ Pumping Kinetics Regulates Timing of Local Ca ²⁺ Releases and Spontaneous Beating Rate of Rabbit Sinoatrial Node Pacemaker Cells

Abstract

The LCR period, a critical determinant of the spontaneous SANC cycle length, is defined by the rate of SR Ca(2+) replenishment, which is critically dependent on SR pumping rate, Ca(2+) available for pumping, supplied by L-type Ca(2+) channel, and ryanodine receptor Ca(2+) release flux, each of which is modulated by cAMP-mediated protein kinase A-dependent phosphorylation.