Changes in Left Ventricular Ejection Fraction and Oxidative Stress after Phosphodiesterase Type-5 Inhibitor Treatment in an Experimental Model of Retrograde Rat Perfusion.

Background and objectives: Taking into consideration the confirmed role of oxidative stress in ischemia/reperfusion injury and the insufficiency in knowledge regarding the phosphodiesterase 5 (PDE5)-mediated effects on the cardiovascular system, the aim of our study was to investigate the influence of two PDE5 inhibitors, tadalafil and vardenafil, with or without the addition of N(G)-nitro-L-arginine methyl ester (L-NAME), on oxidative stress markers, coronary flow and left ventricular function, both ex vivo and in vivo. Methods: This study included 74 male Wistar albino rats divided into two groups. In the first, 24 male Wistar rats were orally treated with tadalafil or vardenafil for four weeks in order to perform in vivo experiments. In the second, the hearts of 50 male Wistar albino were excised and perfused according to the Langendorff technique in order to perform ex vivo experiments. The hearts were perfused with tadalafil (10, 20, 50 and 200 nM), vardenafil (10, 20, 50 and 200 nM) and a combination of tadalafil/vardenafil and L-NAME (30 µM). The CF and oxidative stress markers, including nitrite bioaviability (NO2-), superoxide anion radical (O2-), and the index of lipid peroxidation, were measured in coronary effluent. Results: The L-arginin/NO system acts as the mediator in the tadalafil-induced effects on the cardiovascular system, while it seems that the vardenafil-induced increase in CF was not primarily induced by the NO system. Although tadalafil induced an increase in O2- in the two lowest doses, the general effects of both of the applied PDE5 inhibitors on oxidative stress were not significant. The ejection function was above 50% in both groups. Conclusions: Our results showed that both tadalafil and vardenafil improved the coronary perfusion of the myocardium and LV function by increasing the EF.

Creatine phosphate administration in cardiac ischemia-reperfusion injury in rats: focus on differences between preconditioning, perconditioning, and postconditioning protocols.

The aim of this study was to examine and compare the influence of preconditioning, perconditioning, and postconditioning with creatine phosphate (PCr) on functional recovery and production of prooxidants in isolated rat hearts subjected to ex vivo ischemic-reperfusion (I-R) injury on a Langendorff apparatus. Wistar albino rats (male, n = 40) were divided into four groups: control and groups in which PCr (0.5 mmol/L, 5 min) was perfused before (Pre group), after (Post group), or during (Per group) ex vivo induced ischemia. PCr application was associated with the great benefits of preserving cardiac contractility (in Pre group 100.96% for +(dP/dt max) and 97.61% for -(dP/dt max), in Per group 96.72% for +(dP/dt max) and 95.60% for -(dP/dt max), and in Post group 143.84% for +(dP/dt max) and 104.36% for -(dP/dt max) in relation to the stabilization). In addition, PCr application prevented the increase in prooxidative markers during I-R injury in all therapeutic modalities. The most intensive benefits in the current investigation were observed when PCr was applied during the period of ischemia because the lowest fluctuations in the parameters of cardiac function and oxidative stress were observed. Overall, the results of this study highlight PCr-induced cardioprotection with promising prospects for future clinical use.

Preconditioning with PDE1 Inhibitors and Moderate-Intensity Training Positively Affect Systemic Redox State of Rats.

Taken into consideration that oxidative stress response after preconditioning with phosphodiesterase inhibitors (PDEIs) and moderate physical activity has still not been clarified, the aim of this study was to assess the effects of PDEIs alone or in combination with physical activity, on systemic redox status. The study was carried out on 96 male Wistar albino rats classified into two groups. The first group included animals exposed only to pharmacological preconditioning (PreC) maneuver (sedentary control (CTRL, 1 ml/day saline, n = 12), nicardipine (6 mg/kg/day of NIC, n = 12), vinpocetine (10 mg/kg/day of VIN, n = 12), and nimodipine (NIM 10 mg/kg/day of, n = 12). The second included animals exposed to preconditioning with moderate-intensity training (MIT) on treadmill for 8 weeks. After 5 weeks from the start of training, the animals were divided into four subgroups depending on the medication to be used for pharmacological PreC: moderate-intensity training (MIT+ 1 ml/day saline, n = 12), nicardipine (MIT+ 6 mg/kg/day of NIC, n = 12), vinpocetine (MIT+ 10 mg/kg/day of VIN, n = 12), and nimodipine (MIT+ 10 mg/kg/day of NIM, n = 12). After three weeks of pharmacological preconditioning, the animals were sacrificed. The following oxidative stress parameters were measured spectrophotometrically: nitrites (NO2 -), superoxide anion radical (O2 -), hydrogen peroxide (H2O2), index of lipid peroxidation (TBARS), superoxide dismutase (SOD), catalase (CAT), and reduced glutathione (GSH). Our results showed that PDE1 and MIT preconditioning decreased the release of prooxidants and improved the activity of antioxidant enzymes thus preventing systemic oxidative stress.