ABC | Volume 110, Nº6, June 2018

Original Article Oishi et al Endothelial dysfunction and blood pressure in rats Arq Bras Cardiol. 2018; 110(6):558-567 0 25 50 75 100 –11 –10 –9 –8 –7 –6 –5 –4 –11 –10 –9 –8 –7 –6 –5 –4 % Relaxation 0 25 50 75 100 % Relaxation 0 6 Weeks 12 Weeks 18 Weeks 24 Weeks 0 6 Weeks 12 Weeks 18 Weeks 24 Weeks Log ACH [M] Log ACH [M] ***** A B C 7.75 6.75 7.25 7.50 7.00 pD2 Time (Weeks) CT HFD 0 6 12 18 24 * *+ *+ *+ Figure 3 – Concentration-response curve to acetylcholine (endothelium-dependent relaxation) in aortic rings of rats of the control (CT) (A) and high-fat diet (HFD) group (B) groups and half-maximal response pD2 (C) in both groups. *P < 0.05, CT compared with HFD group in each 6 weeks; + p < 0.05, within-group comparison (0 vs. 6, 6 vs. 12, 12 vs. 18, 18 vs. 24 weeks); seven rats from each group were compared at each time point In the present study, we detected that the levels of inflammatory cytokines TNF- α , IL-6 and CRP increased after 6 weeks in the HFD group and remained higher up to 24 weeks, while the adiponectin concentration was reduced and remained lower in the same period. These results indicate an early development of a low-grade inflammation state in this animal model. TNF- α is involved in the systemic inflammatory response and its levels are increased in the adipose tissue of obese mice compared with lean controls. 20 On the other hand, adiponectin, which improves cardiovascular functions and has anti-inflammatory effects 22 decreased after 6 weeks in HFD group and remained lower up to 24 weeks. Obesity is also associated with an impairment of endothelial cell function and promotes endothelial dysfunction through an array of metabolic disorders including the accumulation of adipose tissue, high blood pressure, dyslipidemia and diabetes, which are linked to vascular oxidative stress. 25 The endothelium comprises the inner lining of blood vessels, and forms the interface between the circulating blood and the 562