RESUMO
There is an urgent need to elucidate the pathogenesis of myocardial ischemia (MI) and potential drug treatments.Here,the anti-MI mechanism and material basis of Ginkgo biloba L.extract (GBE) were studied from the perspective of energy metabolism flux regulation.Metabolic flux analysis (MFA) was performed to investigate energy metabolism flux disorder and the regulatory nodes of GBE components in isoproterenol (ISO)-induced ischemia-like cardiomyocytes.It showed that[U-13C]glucose derived m+2 isotopologues from the upstream tricarboxylic acid (TCA) cycle metabolites were markedly accu-mulated in ISO-injured cardiomyocytes,but the opposite was seen for the downstream metabolites,while their total cellular concentrations were increased.This indicates a blockage of carbon flow from glycolysis and enhanced anaplerosis from other carbon sources.A Seahorse test was used to screen for GBE components with regulatory effects on mitochondrial aerobic respiratory dysfunction.It showed that bilobalide protected against impaired mitochondrial aerobic respiration.MFA also showed that bilobalide significantly modulated the TCA cycle flux,reduced abnormal metabolite accumulation,and balanced the demand of different carbon sources.Western blotting and PCR analysis showed that bilobalide decreased the enhanced expression of key metabolic enzymes in injured cells.Bilobalide's efficacy was verified by in vivo experiments in rats.This is the first report to show that bilobalide,the active ingredient of GBE,protects against MI by rescuing impaired TCA cycle flux.This provides a new mechanism and potential drug treatment for MI.It also shows the potential of MFA/Seahorse combi-nation as a powerful strategy for pharmacological research on herbal medicine.
RESUMO
No presente trabalho, determinaram-se as trocas gasosas de folhas de figueira 'Roxo de valinhos' e o ciclo fotossintético por meio da relação isotópica 12C/13C. Essas medidas foram realizadas sempre na região mediana das folhas, completamente expandidas e totalmente expostas à radiação solar, no período das 09h00min às 10h30min. As folhas fotossinteticamente ativas da figueira apresentaram área foliar em torno de 160cm², com uma assimilação de 14,38µmol m-2 s-1 de CO2, cujos valores isotópicos médios no ramo 1 e no 2 são -28,98±0,69 e -29,28±0,85, respectivamente. Com base nos valores da fotossíntese máxima e na discriminação isotópica do 13C, evidenciou-se que a figueira pode ser considerada uma planta do ciclo fotossintético C3.
In the present research, it was determined the gas exchange of the 'Roxo de Valinhos' fig tree and the cycle photosynthetic through the isotopic relation 12C/13C. These measures were always carried in the average region of the leaves, completely expanded, entirely displayed to the solar radiation, in the period from 09h00min to 10h30min. The sheets photosynthetic active leaf area had around 160cm², with 14.38 -2 s-1 assimilation CO2, and mean isotopic values in the branch 1 and 2 of -28.98±0.69 and -29.28±0,85, respectively. Based in the values of the maximum photosynthesis and in the discrimination isotopic of the 13C, the fig tree can be considered a plant which belongs to photosynthetic C3 cycle.