Division of Pulmonary Medicine, Medical University, Sofia; Georgi Sofiiski 1str, Sofia, 1431, Pierce O'Macchoni 7str, ap.3., Bulgaria.
Introduction: Resistin is a novel adipokine that has been reported as an independent predictor for hypertension. Its role in patients with obstructive sleep apnea (OSA), however, has not been investigated yet.
Aim: The aim of this study was to explore the role of resistin in non-diabetic OSA patients with nocturnal hypertension and to study its association with markers of obesity, insulin resistance and oxidative stress.
Methods: A total of 54 non-diabetic hypertensive OSA patients participated in the study. OSA was newly detected by a standard polysomnography. Patients had controlled hypertension. According to ambulatory blood pressure monitoring (ABPM) they were divided into patients with normal nocturnal BP (25) and patients with nocturnal hypertension (29). Anthropometric, sleep study and glucometabolic parameters were defined. Resistin plasma levels were determined by an ELISA kit. Oxidative stress (urinary 8-isoprostane levels) were measured in addition by mass spectrometry (Cayman Chemical, USA).
Results: Resistin plasma levels were higher in subjects with nocturnal hypertension in comparison to those with normal BP - (7.81±4.43 vs 4.90±2.92ng/mL). Resistin correlated neither to markers of adiposity, nor to those of insulin resistance. Its association with urinary isoprostane levels was of significance (p-0.036). Resistin was higher in patients with severe apnea, but was not associated with respiratory disturbance parameters.
Conclusion: Our results suggest that hyperresistinemia is associated with higher levels of oxidative stress and may contribute to the pathogenesis of nocturnal hypertension in non-diabetic OSA patients. This may provide adequate cardiovascular risk assessment and improve the therapeutic control.