Epicardial adipose tissue expression of adiponectin is lower in patients with hypertension

Low plasma adiponectin levels are related to a higher risk of development of metabolic and cardiovascular disorders, including hypertension (HT). To date, there have been no studies supporting the relationship between epicardial adipose tissue (EAT) expression of adiponectin and HT. We collected samples of EAT from 116 patients undergoing elective cardiac surgery, mostly for coronary artery bypass grafting (n = 54), valve surgery (n = 49) or both (n = 12). Samples of subcutaneous adipose tissue (SAT) were harvested from 85 patients. After RNA isolation, the expression of adiponectin was analysed by real-time retrotranscriptase (RT)-PCR. Baseline clinical data were obtained from medical records. The diagnosis of HT was established mostly by the patients' general physicians following current guidelines. We included 84 hypertensive and 32 non-hypertensive patients. Mean (+/-s.d.) age was 70.3+/-7.9 years. EAT expression levels of adiponectin were lower in hypertensives (14.0+/-3.6 vs 15.3+/-3.6 arbitrary units (a.u.), P = 0.06). This difference was statistically significant (odds ratio (OR) 0.828 per a.u., P = 0.020) after adjustment for age, gender, body mass index, diabetes mellitus, heart failure, coronary artery disease (CAD), total cholesterol and triglyceride levels. However, SAT adiponectin mRNA levels were similar in hypertensive and non-hypertensive patients (15.3+/-4.2 vs 15.3+/-5.0 a.u., P > 0.99). Adjustment for potential confounding factors hardly altered this result. Our findings indicate that EAT expression of adiponectin may be associated with HT status independently of CAD or other comorbidities, whereas SAT expression does not. These results support the hypothesis that EAT is actively implicated in global cardiovascular risk, describing its association with HT.