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Introduction/Aim: Regular exercise may have beneficial effects on high blood-pressure, as shown in different types of experimental hypertension models in rats. The present study aims to investigate the effects of 6-week swimming training on blood pressure, oxidative stress variables of selected tissues, serum adrenomedullin (ADM) levels, and in situ muscle contraction in rats with hypertension induced by Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME), an inhibitor of endothelial nitric oxide synthases (eNOs). Materials and Methods: Twenty-six male Sprague Dawley, 8 weeks of age, rats were randomly divided into four groups: (I) normotensive (C), (II) normotensive + exercise (E), (III) hypertensive (L), and (IV) hypertensive + exercise (LE). Hypertension was induced by the oral administration of L-NAME (60 mg/kg) for 6 weeks. Exercise was performed 5 times (1-h each) per week for 6 weeks. At the end of the experiment, blood and tissue samples (the gastrocnemius muscle, heart, kidney, and thoracic aorta) were collected following contractile properties of the gastrocnemius muscle in situ weredetermined. In the collected tissues, oxidative stress (e.g., lipid oxidation and antioxidant enzyme activity) and serum ADM levels were measured. 6-week L-NAME administration per se (Group L) led to a significant increase in systolic and diastolic blood pressure compared to other groups. Results: Importantly, 6-week exercise caused a protective effect of high blood pressure in the rats received L-NAME (Group LE). The level of ADM was lower in the rats received L-NAME than that of the control group. L-NAME increased lipid peroxidation in the thoracic aorta and decreased superoxide dismutase in the heart, kidney and muscle, and decreased catalase and glutathione in the heart. However, the exercise intervention did not have protective effect on the L-NAME-mediated oxidative damage in the collected tissues. Conclusion: In conclusion, 6-week exercise intervention rescued rats from high blood pressure, but did not have ameliorative effect on the decreased ADM levels.

The aim of this study was to investigate the short-term effects of statins on rat skeletal muscle with the use of electrophysiological methods. A total of 28 adult male Wistar albino rats were given atorvastatin, rosuvastatin, and pravastatin (40 mg/kg each) intragastrically for four weeks. At the end of the study, the gastrocnemius muscle was isolated from the surrounding tissues under deep anaesthesia. It was tied with silk thread in the Achilles tendon area and then connected to an isometric force transducer. The contractile properties of the gastrocnemius muscle were assessed. Serum levels of total cholesterol and creatine kinase (CK) were measured. The muscle tissue samples were stained with hematoxylin eosin and histopathologically evaluated under light microscope. The findings revealed that cholesterol levels were significantly lower in all groups except the control group, whereas CK levels were higher in the statin groups than the control group. All three statins decreased the contractile strength and caused fatigue quickly in the gastrocnemius muscle. Histopathological changes in gastrocnemius muscle were more related to early moderate necrosis in rats that were received statins. This study demonstrates that all three statins decrease the ability of skeletal muscle to generate force and its resistance to fatigue in rats.