Modulation of intramitochondrial free Ca2+ concentration by antagonists of Na(+)-Ca2+ exchange.

Evidence has accumulated in the past decade suggesting that Ca2+ acts as a second messenger not only in the cytosol of the heart to regulate contractility, but also within the mitochondria to regulate the rate of oxidative ATP synthesis. Just as elucidation of the second messenger pathways for Ca2+ in the cytosol has led to the development of pharmacological interventions that alter mechanical functioning of the heart, understanding the role of Ca2+ as a second messenger within the mitochondria and the mechanisms by which this organelle transports and regulates Ca2+ has exciting potential for developing pharmacological interventions that alter myocardial energy metabolism. In this article, David Cox and Mohammed Matlib discuss the potential consequences of pharmacologically increasing the intramitochondrial Ca2+ concentration on myocardial energy metabolism, and suggest some pathological conditions in which such an effect may be beneficial.