Calcium signal transmission between ryanodine receptors and mitochondria in cardiac muscle

Ryanodine receptor (RyR) mediated Ca2+ signals play a central role in excit ation-contraction coupling in cardiac muscle. To support the rhythmic contr actile activity there is a need for continuous tuning of cellular oxidative energy generation in the mitochondria to the actual work-load. Evidence ha s emerged that RyR-mediated cytosolic Ca2+ signals are efficiently transmit ted to the mitochondria, providing a means for coupling cardiac muscle exci tation to oxidative energy production, through activation of Ca2+ sensitive mitochondrial dehydrogenases. Recent data suggest that the Ca2+ signal tra nsmission between RyR and mitochondria is dependent on local Ca2+ interacti ons between subdomains of sarcoplasmic reticulum (SR) and mitochondria. Her e we give a short overview of the determinants and spatio-temporal organiza tion of Ca2+ signal transmission between SR and mitochondria. (Trends Cardi ovasc Med 2001;11:269-275). (C) 2001, Elsevier Science Inc.