TLX2 and heart failure: In the case of heart failure, any increase in LCS production could exacerbate the existing problem of slowed Ca2+ reuptake because of decreased SERCA2a activity.31 Further complexity is added by the changes in Ca2+ transient time course also affecting LTCC gating via prolongation of the AP because of NCX-generated current during the declining phase of the Ca2+ transient,13 as well as the differential responses of coupled and uncoupled release sites.32