Effects of Chinese herbal monomers on oxidative phosphorylation and membrane potential in cerebral mitochondria isolated from hypoxia-exposed rats in vitro★

Mitochondrial dysfunction is the key pathogenic mechanism of cerebral injury induced by high-altitude hypoxia. Some Chinese herbal monomers may exert anti-hypoxic effects through enhancing the efficiency of oxidative phosphorylation. In this study, effects of 10 kinds of Chinese herbal monomers on mitochondrial respiration and membrane potential of cerebral mitochondria isolated from hypoxia-exposed rats in vitro were investigated to screen anti-hypoxic drugs. Rats were exposed to a low-pressure environment of 405.35 mm Hg (54.04 kPa) for 3 days to establish high-altitude hypoxic models. Cerebral mitochondria were isolated and treated with different concentrations of Chinese herbal monomers (sinomenine, silymarin, glycyrrhizic acid, baicalin, quercetin, ginkgolide B, saffron, piperine, ginsenoside Rg1 and oxymatrine) for 5 minutes in vitro. Mitochondrial oxygen consumption and membrane potential were measured using a Clark oxygen electrode and the rhodamine 123 fluorescence analysis method, respectively. Hypoxic exposure significantly decreased the state 3 respiratory rate, respiratory control rate and mitochondrial membrane potential, and significantly increased the state 4 respiratory rate. Treatment with saffron, ginsenoside Rg1 and oxymatrine increased the respiratory control rate in cerebral mitochondria isolated from hypoxia-exposed rats in dose-dependent manners in vitro, while ginsenoside Rg1, piperine and oxymatrine significantly increased the mitochondrial membrane potential in cerebral mitochondria from hypoxia-exposed rats. The Chinese herbal monomers saffron, ginsenoside Rg1, piperine and oxymatrine could thus improve cerebral mitochondrial disorders in oxidative phosphorylation induced by hypobaric hypoxia exposure in vitro.