Impaired tricarboxylic acid cycle flux and mitochondrial aerobic respiration during isoproterenol induced myocardial ischemia is rescued by bilobalide

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-13 C]glucose derived m+2 isotopologues from the upstream tricarboxylic acid(TCA)cycle metabolites were markedly accumulated 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 combination as a powerful strategy for pharmacological research on herbal medicine.

Inherited disturbances of phenylalanine metabolic kinetics in essential hypert ension

Objective To clarify whether the disturbances in metabolic kinetics of the essential aminoacid, phenylalanine (phe), are implicated in the genetic pathogenesis of essential hypertension (EH).Methods 1. L-(2, 3D3)-leucine, L-(2, 3D3)-isoleucine, L-15N-lysine, L-(2, 3D3)-valine and L-(2, 3D3)-phe were used for simultaneously studying comparative metabolic kinetics using stable isotope tracer methods with a GC-MS system. Study groups were the offspring with both parents suffering EH (n=10, FH+), 2 or more than 2 parents and grand-parents with EH and stroke (n=12, FS+) and those without genetic predisposition of EH and stroke (n=12, F) groups. 2. By comparing the radioactive counts of ［3H］-phe, and their weight transformation in blood after 1.5?Ci/kg i.v. administration at defined intervals and in tissues obtained after being sacrified among spontaneously hypertensive rats (SHR), 2 kidney-1 clip hypertensive rats (2K1C) and their normotensive controls (WKY). 3. The time transport and concentration transport of ［3H］-L-phe in cpm between the cultured vascular smooth muscle cell of 5th generation in SHR and WKY were compared.Results A single and unique disturbance of metabolic kinetics in phe were found in FH+, FS+ and SHR. The plasma pool or apparent volume of distribution was enlarged, and the turnover rate constants between plasma and cell tended to show a decrease. The pharmacokinetics of phe in 2K1C was not changed. Only phe content in heart and aorta, the vital organs for predicting BP, were higher in SHR than in WKY tissues studied. Both the time and concentration transport were higher in SHR, e.g., an increment in the net-uptake of L-phe by vascular tissue.Conclusion A unique aberrant of metabolic kinetics of phe might be implicated in the inherited pathogenesis of EH and stroke both from clinical and animal studies.