Book of Abstracts - New Frontiers 2022

Abstracts of oral presentations

ERYTHROCYTE AND PLASMA PROPERTIES IN MONOCROTALINE MODEL OF PULMONARY ARTERIAL HYPERTENSION T. Jasenovec 1 , D. Radošinská 2 , M. Kollarová 1 , N. Vrbjar 3 , P. Bališ 3 , S. Trubačová 4 , Ľ. Paulis 4 , L. Tóthová 5 , J. Radošinská 1,3 1 Institute of Physiology, Faculty of Medicine, Comenius University, Bratislava, Slovakia; 2 Institute of Immunology, Faculty of Medicine, Comenius University, Bratislava, Slovakia; 3 Centre of Experimental Medicine, Slovak Academy of Sciences, Bratislava, Slovakia; 4 Institute of Pathophysiology, Faculty of Medicine, Comenius University, Bratislava, 5 Slovakia; Institute of Molecular Biomedicine, Faculty of Medicine, Comenius University, Bratislava, Slovakia Introduction: Monocrotaline (MCT) is a toxic alkaloid used for the induction of pulmonary arterial hypertension (PAH) in experimental animals. After injection, MCT is bound to erythrocytes. In the oxygen rich environment of pulmonary precapillary arterioles and capillaries, MCT is released and causes endothelial cell damage, leading to vascular remodelling and consecutively to PAH development. Modulations of renin-angiotensin-aldosterone system (RAS), and matrix metalloproteinases are involved in its pathogenesis. In patients with PAH, several parameters of erythrocytes deteriorate, such as erythrocyte deformability (ED) or aggregability. However, changes in other erythrocyte parameters have not yet been fully described in MCT model of PAH. Bosentan is an available medicament used in treatment of PAH. Its effect on erythrocytes remains unclear. Therefore, we focused on the characterization of the erythrocyte parameters, the RAS system in the MCT model, and the possible effect of bosentan treatment. Methods: The experiment was carried out on 12-week-old Wistar rats (n = 30) divided into 3 groups: control group; MCT-treated group (60 mg/kg) and MCT- and bosentan-treated group (300 mg/kg/day). After 4 weeks of experiment, ED was determined by the filtration method and erythrocyte NO production using DAF-2 DA fluorescence probe. Plasma oxidation state parameters, erythrocyte osmotic resistance and erythrocyte Na,K-ATPase kinetic parameters were measured spectrometrically/spectrofluorometrically. The concentration of each component of RAS was determined by liquid chromatography-tandem mass spectroscopy. Results: The administration of MCT decreased haematocrit. It also increased Vmax and decreased KNa kinetic parameters of Na,K-ATPase. Moreover, an activation of the alternative pathway of renin angiotensin system (increased Ang I, Ang 1-7, and Ang 1-5 without changes in Ang II level) and down regulation of aldosterone was also observed. Bosentan treatment improved ED, decreased AOPP and fructosamine level as well as increased GSH/GSSG ratio. Conclusion: Our findings don’t entirely match with findings in patients with PAH reporting an increase in Ang II levels, increase in oxidative stress and deterioration in ED. Within the observed erythrocyte parameters, MCT administration only impaired Na+ binding properties of Na,K-ATPase, which probably led to a compensatory increase in the number of enzyme active molecules. Bosentan treatment enhanced ED in MCT-treated animals which can also contribute to the improvement of hemodynamics in the condition of PAH. This effect is most likely due to the antioxidant effect of bosentan, since several markers of oxidative state improved. To obtain more comparable erythrocyte parameters as in human PAH, adjustments to used model might be appropriate (e.g. different age of animal, MCT dosage, experiment duration).

Keywords: erythrocyte, pulmonary arterial hypertension, bosentan

Funding:VEGA 1/0193/21

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