Original article Methylene blue attenuates mitochondrial dysfunction of rat kidney during experimental acute pancreatitis Irma KULIAVIENE,* Rasa BANIENE, † Simona VIRKETYTE, † Marius KINCIUS, ‡ Eugene JANSEN, § Antanas GULBINAS, ‡ Limas KUPCINSKAS,* ,‡ Sonata TRUMBECKAITE † & Vilmante BORUTAITE † * Department of Gastroenterology, † Neuroscience Institute, ‡ Institute for Digestive Research, Medical Academy, Lithuanian University of Health Sciences, Kaunas, Lithuania, and § Centre for Health Protection, National Institute for Public Health and the Environment, Bilthoven, the Netherlands OBJECTIVE: The disturbance of mitochondrial functions has been considered as one of the mecha- nisms of pathogenesis of acute pancreatitis (AP) followed by kidney failure. This study was aimed to investigate the effects of methylene blue (MB) on pan- creas and kidney mitochondrial respiratory functions during experimental acute pancreatitis in rats. METHODS: AP was induced by administrating so- dium taurocholate into the pancreatic duct of male Wistar rats. The rats were divided into three groups: the MB group, MB (5 mg/kg) was injected intrave- nously 10 min prior to AP induction; the AP group, saline solution was injected intravenously 10 min prior to AP induction; and the sham operation group, isotonic sodium chlorine was used instead of sodium taurocholate. The animals were sacrificed after 24 h. The pancreas and kidney were removed for mitochondrial assay by oxygraphic and spectro- photometric methods. RESULTS: Intravenous injection of MB did not pre- vent AP-induced inhibition of pancreatic mitochon- drial respiration; however, MB significantly improved kidney mitochondrial respiratory functions with com- plex I-dependent substrates glutamate and malate. The activity of complex I of mitochondria isolated from AP-damaged kidney was increased after pretreatment with MB. However, MB did not affect AP-inhibited kidney mitochondrial respiration with succinate. MB had no protective effects on amylase activity or on urea content in serum in AP. CONCLUSION: The disturbances of kidney mito- chondrial energy metabolism in experimental model of severe AP can be ameliorated by MB administration. KEY WORDS: kidney, methylene blue, mitochondria, pancreatitis, Wistar rats. INTRODUCTION Acute pancreatitis (AP) is an inflammatory disease of the exocrine pancreas with systemic responses. It is as- sociated with local and systemic complications in approximately 20–30% of the cases. The overall mor- tality rate is 5–15%. 1 Multiple organ failure (OF) and pancreatic infection are the main causes of death; 2,3 the mortality of patients with OF is about 30%. 2 And there are still no effective treatments for the disease and its complications. Various studies have demonstrated that the distur- bance of pancreatic mitochondrial functions occurs early at the onset of AP. 4–7 Recently, we found that kidney mitochondria are also injured during the first 24 h after the onset of severe AP and this may contrib- ute to renal dysfunction. 8 Correspondence to: Irma KULIAVIENE, Department of Gastroenterology, Medical Academy, Lithuanian University of Health Sciences, Eiveniu 2, Kaunas LT-50009, Lithuania. Email: irma.kuliaviene@gmail.com Conflict of interest: None. C 2016 Chinese Medical Association Shanghai Branch, Chinese Society of Gastroenterology, Renji Hospital Affiliated to Shanghai Jiaotong University School of Medicine and John Wiley & Sons Australia, Ltd Journal of Digestive Diseases 2016; 17; 186–192 doi: 10.1111/1751-2980.12328 186