CaMKII-dependent myofilament Ca2+ desensitization contributes to the frequency-dependent acceleration of relaxation

- SR-Ca2+ uptake is not the only mechanism underlying FDAR regulation.
- CaMKII binds and phosphorylates TnI at sites distinct from the PKA and PKC sites.
- CaMKII-dependent TnI phosphorylation is involved in FDMCD and the consequent FDAR.