Long-acting phosphodiesterase 5 inhibitor, tadalafil, and superoxide dismutase mimetic, tempol, protect against acute hypoxia-induced pulmonary hypertension in rats:

Long-acting phosphodiesterase 5 (PDE5) inhibitor, tadalafil, was recently approved for the treatment of pulmonary hypertension. Apart from being a PDE5 inhibitor, tadalafil also possesses antioxidant activity. The aim of this study was to probe whether tadalafil has any beneficial effect over tempol owing to its antioxidant action in addition to PDE5 inhibitory activity. Albino Wistar rats were pretreated with tadalafil (10 mg/kg) or vehicle 2 h before hypoxic exposure, whereas tempol (20 mg/kg) was given 5 min before induction of hypoxia. Right ventricular systolic pressure (RVSP), mean arterial pressure (MAP), heart rate (HR), right ventricular contractility (RVdP/dtmax) and cardiac output (CO) were recorded while subjecting rats to acute hypoxia for 30 min. Lipid peroxidation and reduced glutathione were estimated in serum before and after hypoxia exposure. Tadalafil as well as tempol significantly prevented hypoxia-induced rise in RVSP (p < 0.001) and RVdP/dtmax (p < 0.05). Both tadalafil and tempol p...