Bootcongres

Introduction: N-octanoyl dopamine (NOD) is a lipophilic non-hemodynamic dopamine derivative with potent anti-inflammatory properties. We showed that NOD reduces acute rejection in a rat kidney transplantation model and protects cardiomyocytes from cold ischemia/reperfusion (CI/R) injury in vivo. For both inflammation and CI/R injury, mitochondria in target organs have been identified as key players. Some lipophilic substances as ceramides, N-acylethanolamines and others have been described to decrease state 3 respiration (oxygen consumption of the ATP-synthase under the influence of ADP), with a subsequent decrease of the respiratory control ratio (RCR; state 3/state 4 (inhibition of the ATP-Synthase)). The aim of this study is to show that NOD may also reduce the RCR, possibly by the induction of a hypo-metabolism and might limit the production of reactive oxygen species. Methods: Liver and kidney mitochondria were isolated from Dark Agouti rats (n= 5). With a Clark-Electrode the oxygen consumption was measured with (1µM / 100µM) or without NOD, followed by stimulation with the typical substrates and inhibitors (ADP, antimycin, CCCP, cytochrome C, glutamate/malate, oligomycin, rotenone/succinate and ascorbate/TMPD) to investigate the function of each complex. Membrane potential and ROS production were determined with fluorescence microscopy in cultured cytokine-stimulated primary hepatocytes and kidney cells +/- NOD. Results: Liver and kidney mitochondria both showed a dose dependent reduction of oxygen consumption in the presence of NOD after stimulation with ADP and a subsequent reduction of the RCR (liver: state3 respiration/RCR - control vs. NOD 100µM, p=0,0172/ p=0,001; kidney: state 3 respiration/RCR- control vs. NOD 100µM, p=0,0121/ p=0,0259). The other respiratory states showed no differences. We hope to also soon be able to present our fluorescence microscopy data. Conclusion: NOD inhibits the state 3 respiration in mitochondria. This might be the result of an induced hypo-metabolism and could make mitochondria more resilient.