BACKGROUND: An isodamine, a kind of alkaloid, is extracted from Anisodus tanguticus (Maxim.) Pascher and is also a good protective agent of cell. However, functional change of mitochondrion is the most sensitive index reflecting cell injury.OBJECTIVE: To study the effects of anisodamine on brain mitochondrial damage following global cerebral ischemia and reperfusion in domestic rabbits and explore its mechanism.DESIGN: Totally randomized controlled trials.SETTING: Emergency Department of Tongji Hospital, Tongji Medical College of Huazhong University of Science and Technology.MATERIALS: The experiment was carried out in the laboratory of Emergency Department, Tongji Hospital Affiliated to Tongji Medical College of Huazhong University of Science and Technology, from September to December in 2002. Thirty healthy domestic rabbits of either sex were used and randomized into sham-operation group, ischemia-reperfusion group and anisodamine group with 10 rabbits in each group.METHODS: The models of complete cerebral ischemia and reperfusion injury in rabbits were established by ligation of bilateral common carotids and vertebral arteries with systemic hypotension, ischemia lasting for 20 minutes followed by 2-hour reperfusion. Anisodamine group was injected with anisodamine at a dose of 10 mg/kg body mass via femoral vein one minute before reperfusion, and lasted for 2 hours at a dose of 5 mg/hour by micro-pump. Ischemia-reperfusion group was treated with normal saline of the same volume. Sham-operation group only underwent used to determine mitochondrial respiratory functions, including respiratory control rate (RCR), the ratio of adenosine diphosphate to oxygen nicotinamide adenine dinucleotide hydrogenated (NADH) oxidase, succinate oxidase and cytochrome C oxidase were measured by the oxygenmethod of Yagi.drial calcium (Ca2+) and malondiadhyde (MDA) in cortex.reperfusion group and anisodamine group, RCR, ADP/O, OPR levels were lower than those in sham-operation group [nicotinamide adenine dinucleotide chain: RCR: 2.34±0.18,3.58±0.29,4.07±0.38,P ＜ 0.05-0.01;ADP/O: 1.77±0.10,2.23±0.14,2.41±0.17,P ＜ 0.05-0.01; OPR: (5.27±0.78),(8.03±1.30), (9.63±1.50)μkat/g, P ＜ 0.05-0.01; flavin adenine dinucleotide chain: RCR: 1.47±0.23,2.53±0.28,2.84±0.36,P ＜ 0.05-0.01;ADP/O: 0.88±0.09,1.58±0.11,1.73±0.17 ,P ＜ 0.05-0.01; OPR: (6.05±1.13),(7.47±1.40), (8.62±1.60)μkat/g,P ＜ 0.05-0.01], and those were higher in chemia-reperfusion group and anisodamine group, the activities of respiratory chain oxidase of NADH, succinate and cytochrome C were lower than those in sham-operation group [NADH: (2.62±0.35), (4.55±0.48), (5.07±0.60)μkat/g;succinate: (1.48±0.17), (1.83±0.22), (2.10±0.28)μkat/g; cytochrome C:(5.03±1.12), (7.62±1.23), (9.00±1.53)μkat/g, P ＜ 0.05-0.01], and those were higher in anisodamine group than in ischemia-reperfusion group, the content of mitochondrial Ca2+ [(2.36±0.23), (1.39±0.17),(1.22±0.12) mg/g] and MDA [(36.38±10.42), (22.69±9.56), (19.74±7.26)μmol/g,(P ＜ 0.05-0.01 )] was higher than that in sham-operation group, and it was lower in anisodamine group than in ischemia-reperfusion group (P ＜ 0.01).CONCLUSION: Anisodamine can protect the brain against ischemiareperfusion injury at the level of mitochondria by antagonism of Ca2+, inhibition of lipid peroxidation, stabilization of mitochondrial membrane, alleviation of mitochondrial damage, and improvement of motochondrial respiratory functions and the activities of enzymes of respiratory chain.