TY - JOUR T1 - Protamine sulfate induces mitochondrial hyperpolarization and a subsequent increase in reactive oxygen species production JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther DO - 10.1124/jpet.119.257725 SP - jpet.119.257725 AU - Rabia Ramzan AU - Susanne Michels AU - Petra Weber AU - Annika Rhiel AU - Marc Irqsusi AU - Ardawan J. Rastan AU - Carsten Culmsee AU - Sebastian Vogt Y1 - 2019/01/01 UR - http://jpet.aspetjournals.org/content/early/2019/06/03/jpet.119.257725.abstract N2 - Protamine sulfate (PS) is widely used in heart surgery as an antidote for heparin albeit its pharmacological effects are not fully understood and applications are often accompanied by unwanted side effects. Here, we show the effect of PS on mitochondrial bioenergetics profile resulting in mitochondrial reactive oxygen species (ROS) production. Polarographic measurements were performed in parallel to membrane potential and ROS measurements by FACS analyzer using tetramethylrhodamine ethyl ester (TMRE) and MitoSOXTM fluorescent dyes, respectively. PS inhibited intact rat heart mitochondrial respiration (stimulated by ADP) to 76% (p < 0.001) from the baseline of 51.6 ± 6.9 to 12.4 ± 2.3 nmol O2 min-1 ml-1. Same effect was found when respiration was priorly inhibited by antimycin A (101.0 ± 8.9 vs. 38.0 ± 9.9 nmol O2 min-1 ml-1, p < 0.001) and later stimulated by substrates of cytochrome oxidase (CytOx) i.e. ascorbate and tetramethyl phenylene diamine (TMPD); suggesting that PS exerted its effect through inhibition of CytOx activity. Furthermore, the inhibition of mitochondrial respiration by PS was concentration-dependent and accompanied by hyperpolarization of the mitochondrial membrane potential (Δψm) i.e. 18 % increase at 50µg/ml and a further 3.3 % increase at 250µg/ml PS compared to control. This effect was associated with a strong consequent increase in the production of ROS i.e. 85 % and 88.6 % compared to control respectively. We propose that this excessive increase in ROS concentrations results in mitochondrial dysfunction and thus might relate to the “protamine reaction” contributing to the development of various cardiovascular adverse effects.SIGNIFICANCE STATEMENT N/A ER -