Calcium signal transmission between ryanodine receptors and mitochondria in cardiac muscle.

Ryanodine receptor (RyR) mediated Ca(2)+ signals play a central role in excitation-contraction coupling in cardiac muscle. To support the rhythmic contractile activity there is a need for continuous tuning of cellular oxidative energy generation in the mitochondria to the actual work-load. Evidence has emerged that RyR-mediated cytosolic Ca(2)+ signals are efficiently transmitted to the mitochondria, providing a means for coupling cardiac muscle excitation to oxidative energy production, through activation of Ca(2)+ sensitive mitochondrial dehydrogenases. Recent data suggest that the Ca(2)+ signal transmission between RyR and mitochondria is dependent on local Ca(2)+ interactions between subdomains of sarcoplasmic reticulum (SR) and mitochondria. Here we give a short overview of the determinants and spatio-temporal organization of Ca(2)+ signal transmission between SR and mitochondria.