No abstract

Background/aim: Atrial natriuretic peptide (ANP) is known as a protective agent against ischemia-reperfusion injury for cardiomyocytes. We compared the hemodynamic effects of ANP and isatin, which is known as an ANP receptor blocker, in ischemia followed by reperfusion in exercised rat hearts with nonexercised ones.Materials and methods: Isolated hearts were perfused in 4 exercised (E) groups after a running protocol for 5 days and 4 nonexercised (NE) groups. In the first protocol, ANP was added to the perfusion solution before ischemia in an E and NE group. In the second protocol, different doses of isatin (0.1, 10, 100 µM/L) were added to the perfusion solution before ANP in 3 E and 3 NE groups. Left ventricular developed pressure (LVDP) and maximum and minimum rates of change in left ventricular pressure (dP/dtmax and dP/ dtmin) were recorded.Results: Higher LVDP and dP/dtmin values were observed in the E group than the NE group following addition of ANP before ischemia. Values of dP/dtmax were higher in the E group at the first minute of reperfusion period. Hemodynamic difference was not observed between groups given the same amount of isatin before ANP. Conclusion:This study indicated that higher ANP concentrations before ischemia were more effective on the left ventricle contractility and relaxation functions in the hearts that were exposed to exercise.

INTRODUCTION: Obstructive sleep apnea syndrome (OSAS) is commonly associated with obesity, insulin resistance, metabolic syndrome, hypertension, and coronary artery disease. Irisin is a newly identified myokine and its serum concentration was found to be correlated with cardiac troponin and creatin kinase-MB in acute myocardial infarction patients. Furthermore, irisin levels were positively associated with endothelium-dependent vasodilation in type 2 diabetic patients. AIM: In this study, we aimed to investigate serum irisin level in the newly diagnosed OSAS patients. MATERIALS AND METHODS: After obtaining ethical approval, 32 OSAS patients were included. All patients gave written informed consent. Diagnosis of OSAS was verified by an overnight polysomnography (PSG) and made by an apnea hypopnea index equal to or higher than 5. Venous blood samples were collected in the morning between 08.00-10.00 after PSG (n=25) or after one-night CPAP treatment (n=7). Serum irisin concentrations were studied by ELISA. RESULTS AND CONCLUSION: Serum irisin concentrations were significantly higher in newly diagnosed OSAS group than in OSAS group after one night of CPAP treatment (199.7±42.4 vs 159.7±18.3 ng/mL respectively; p<0.01). These results suggest that increased serum irisin levels can be reduced by CPAP treatment and elevated serum irisin levels may be due to increased respiratory muscle activity and body temperature.

Exercise may modulate lipolysis via leading to natriuretic peptide secretion and beta-adrenergic activation. Adiponectin, an adipose-secreted multifunctional signaling protein, may be the missing link between exercise and lipolytic activity. In this study, we aimed to investigate the effects of supramaximal exercise on plasma levels of adiponectin, atrial natriuretic peptide (ANP), and Btype natriuretic peptide (BNP) in healthy humans. Thirty-one healthy young adult volunteers (male/female, 15/16; mean age±SD, 20.7±1.7 years) underwent a 30-second Wingate anaerobic exercise test on a cycle ergometer and venous blood sampling before and after the exercise test. Plasma ANP and BNP levels were assayed by radioimmunoassay, whereas adiponectin levels were assayed by enzyme-linked immunosorbent assay. Systolic and diastolic blood pressures, heart rate, hematocrit levels and blood lactate were also measured before and after exercise. The mean plasma adiponectin level significantly increased following a 30-second anaerobic exercise test compared to resting level (17.45±4.70 vs 31.29±5.16 μg/mL, respectively, p<0.001). The mean plasma ANP and BNP levels remained comparable before and after the 30-second anaerobic exercise. A 30-sec supramaximal exercise session enhanced circulating adiponectin levels in both gender groups, whereas ANP and BNP levels exerted nonsignificant alterations. We suggest that acute anaerobic exercise may affect secretory function of adipose tissue which seems not related with natriuretic peptide secretion.

Obstructive sleep apnea (OSA) syndrome has emerged as a major public health problem because of its high prevalence amongst middle-aged, obese men as well as in lean individuals and women. It has been suggested that obesity's role in the genesis of sleep apnea is rather through its metabolic activity than a purely anatomic/mechanical impact. Recent studies demonstrate that circulating levels of adipokines, adipose tissue-derived secretory proteins, are altered in patients with OSA syndrome. For instance, leptin level is increased, whereas that of adiponectin decreased in OSA, and these changes can be reversed by treatment of apnea/hypopnea episodes. Adipokine pro le seems to change towards a proin ammatory pattern that may also contribute to OSA-related cardiometabolic diseases. The mechanisms of adipose dysfunction in OSA includes hypoxia, oxidative stress and increased sympathetic nervous activity, including alterations in the circulating levels of the neurotrophins nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF). In e ect, reversing hypoxia and attenuating oxidative stress and in ammation through adipokine-and NGF/BDNFtargeted pharmacology may provide novel therapeutic opportunities in patients with OSA syndrome.