Ca2+ signal in high-Ca2+ perimitochondrial microdomains is amplified within
the mitochondrial matrix and activates Ca2+-dependent dehydrogenases. In s
teroid-secreting cells, small cytoplasmic Ca2+ signals may also augment mit
ochondrial Ca2+ concentration. The ensuing formation of NADH and NADPH may
have an essential role in supporting the increased steroid secretion.