Anne-Marie Koop

6 229 failure, 33 and miR-199b has shown to be upregulated in PAB, 34 in this study we aim at understanding the contribution of miR-199b to RV remodelling in response to pressure overload induced by pulmonary artery banding (PAB). MATERIAL AND METHODS Animal models and Pulmonary Artery Banding Surgery All animal experiments were performed conform the guidelines from Directive 2010/63/EU of the European Parliament on the protection of animals used for scientific purposes. The procedures were reviewed and approved by the Animal Care and Use Committee of the University of Maastricht and Animal Experiments Committee of the University of Groningen and were performed according to the rules formulated in the Dutch law on care and use of experimental animals (Projects 2012- 035 and 2012-128). Animal models employed in this study consist of mice carrying murine miR- 199b transgene 33 under control of alpha-myosin heavy chain promoter (α -MHC) in C57BL/6 background and non-TG littermates (WT). Pulmonary artery banding (PAB) was performed, as described below, in mice older than 8 weeks of both genders. Animals were anesthetized with isoflurane/air mixture (5% induction; 2–3% maintenance). Animals were intubated with a 20G plastic blunt needle and placed in a supine position on a heating pad (37°C) and ventilated with room air using a Harvard miniventilator (model 687, Hugo Sachs, Germany; respiratory rate 180 breaths per minute and a tidal volume of 125 μL). The pulmonary artery was approached by a left lateral thoracotomy and banded with a 7-0 suture by tying over a 23G needle. Post-operative pain relief was provided with buprenorphine (0.01 mg/kg s.c.) twice daily for 2-3 consecutive days if necessary. Sham-operated animals underwent the same procedure without PAB. At the endpoints of all experiments, mice were anaesthetized by isoflurane and the hearts were harvested. All efforts were made to minimize suffering. Hemodynamic analyses Hemodynamic function was assessed by both echocardiography and cardiac magnetic resonance imaging (MRI) during anesthesia with 1.5-3% isoflurane in a 2:1 mixture of air (0.3L/min) and oxygen (0.15L/min) and warming at 37°C. Echocardiography was performed using a Vivid Dimension 7 and i13L-transducer (GE Healthcare, Waukesha, WI, USA). Pulmonary artery banding gradient, right ventricular dimensions and tricuspid annular plane systolic excursion (TAPSE) were assessed with echocardiography at two, four and six weeks, from short-axis at aorta level,