Kynurenic acid influences the respiratory parameters of rat heart mitochondria

In the present study the effect of L-kynurenine, kynurenic acid and quinoli nic acid on the heart mitochondrial function were investigated. Mitochondri a were incubated with saturating concentrations of respiratory substrates g lutamate/malate (5 mmol/l), succinate (10 mmol/l) or NADH (1 mmol/l), with and without kynurenines. The concentration of kynurenines varied between 1. 25 mu mol/l and 10 mmol/l, From all investigated kynurenines, only kynureni c acid affected dose-dependently the respiratory parameters of heart mitoch ondria. Respiratory control and P/O values were reduced significantly with glutamate/malate and moderately with succinate as substrates in the presenc e of 125 mu mol/l to 10 mmol/l kynurenic acid. A known elevation of L-kynur enine in the blood of patients with ischemic heart disease or essential hyp ertension may suggest the involvement of L-kynurenine metabolites in the im pairment of heart mitochondrial function, for example in cardiomyopathy. Co pyright (C) 2001 S. Karger AG, Basel.