Purpose of this study: to perform a comparative evaluation of the effects of NO modulators (L-arginine, Thiotriazoline, angiotensin, and Mildronate) on various markers of endothelial dysfunction (sEPCR, Tie-2, VEGF-B, endothelial cell nuclear density) and the antioxidant system (Cu/ZnSOD, GPX1, GPX4) following experimental PH and to justify further investigation into the cardio- and endothelioprotective effects of the most promising pharmacological agent. Here, GPX1 is linked to endothelial dysfunction.