However, we found that 15 min pre-perfusion with 100 μM 5-HD did not alter DETA/NO-induced protection against ischemia-induced cytochrome c release: mitochondrial cytochrome c content in nmol/mg mitochondrial protein was 0.43 ± 0.03 in control, 0.30 ± 0.02 in 30 min ischemic, 0.37 ± 0.01 in DETA/NO-pretreated ischemic, and 0.37 ± 0.01 in DETA/NO- plus 5-HD-pretreated ischemic mitochondria (n = 4) suggesting that the protective effect of DETA/NO is not mediated through mtKATP channels. Here, CYCS is linked to ischemia.