Role of intracellular calcium dynamics in the short-term memory in CVM model: a simulation study

Many experimental studies claimed that, short-term memory, an intrinsic property of paced cardiac myocytes, has been regulated by either intracellular calcium cycling or membrane ionic currents, manifested by a time constant of cellular action potential duration (APD) restitution. Although both factors play important roles in short-term memory, their respective effects have not been well understood currently. In this study, we used an ionic model of canine ventricular myocytes (CVM) to investigate the effect of calcium release from the sacroplasm reticulum (SR), as well as the effect of L-type calcium current, on cardiac short-term memory. We calculated short-term memory response by testing the time to reach steady-state APD after an abrupt shortening of basic cycling length (BCL) in pacing protocol. Our results indicated that as the release of calcium from SR was gradually prevented, short-term memory response decreased, while the blockade of L-type calcium channel had little effect on short-term memory. Finally, we declared that the amount of intracellular calcium released from SR affected short-term memory of cardiac tissues more than that of L-type calcium channel.