Sarcoplasmic Reticulum Ca 2+ and Heart Failure

eart failure (HF) is a leading cause of death and enormous effort has focused at understanding the molecular and cellular mechanisms of the decreased cardiac contractility. While changes of other components contribute, it is generally agreed that much of the contractile deficit is due to reduced myocyte Ca 2 transients. Alterations in Ca 2 current (I Ca ) and action potential characteristics are also seen in HF, but a central factor limiting Ca 2 transient amplitude is a decrease of sarcoplasmic reticulum (SR) Ca 2 content. 3-6 HF is extremely complex, but it is easy to appreciate how reduced SR Ca 2 content would reduce SR Ca 2 release, myofilament activation, and contractility. Despite agreement that SR Ca 2 content is reduced in HF, controversy exists about why SR content is low.