Cardiac Dysfunction Induced by Obesity Is Not Related to beta-Adrenergic System Impairment at the Receptor-Signalling Pathway

Author(s)

Togneri Ferron, Artur Junio ^[1] ; Jacobsen, Bruno Barcellos ^[1] ; St Ana, Paula Grippa ^[2] ; Salome de Campos, Dijon Henrique ^[2] ; de Tomasi, Loreta Casquel ^[2] ; Mello Luvizotto, Renata de Azevedo ^[3] ; Cicogna, Antonio Carlos ^[2] ; Leopoldo, Andre Soares ^[1] ; Lima-Leopoldo, Ana Paula ^[1]

Affiliation

^[1] Univ Fed Espirito Santo, Dept Sports, Ctr Phys Educ & Sports, Vitoria, ES - Brazil

^[2] Univ Estadual Paulista, UNESP, Dept Clin & Cardiol, Sch Med, Botucatu, SP - Brazil

^[3] Univ Fed Mato Grosso, Inst Ciencias Saude, Sinop, Mato Grosso - Brazil

• Document type: Journal article
• Source: PLoS One; v. 10, n. 9 SEP 21 2015.
• Web of Science Citations: 8

Abstract

Obesity has been shown to impair myocardial performance. Some factors have been suggested as responsible for possible cardiac abnormalities in models of obesity, among them beta-adrenergic (beta A) system, an important mechanism of regulation of myocardial contraction and relaxation. The objective of present study was to evaluate the involvement of beta A system components in myocardial dysfunction induced by obesity. Thirty-day-old male Wistar rats were distributed in control (C, n = 25) and obese (Ob, n = 25) groups. The C group was fed a standard diet and Ob group was fed four unsaturated high-fat diets for 15 weeks. Cardiac function was evaluated by isolated papillary muscle preparation and beta A system evaluated by using cumulative concentrations of isoproterenol and Western blot. After 15 weeks, the Ob rats developed higher adiposity index than C rats and several comorbidities; however, were not associated with changes in systolic blood pressure. Obesity caused structural changes and the myocardial responsiveness to post-rest contraction stimulus and increased extracellular calcium (Ca2+) was compromised. There were no changes in cardiac function between groups after beta A stimulation. The obesity was not accompanied by changes in protein expression of G protein subunit alpha (Gs alpha) and beta A receptors (beta(1)AR and beta(2)AR). In conclusion, the myocardial dysfunction caused by unsaturated high-fat diet-induced obesity, after 15 weeks, is not related to beta AR system impairment at the receptor-signalling pathway. (AU)

• FAPESP's process: 12/16647-0 - Participation of adrenergic system in the myocardial dysfunction induced by obesity
• Grantee: Antonio Carlos Cicogna
• Support Opportunities: Regular Research Grants