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

• Published in: PloS one Vol. 10; no. 9
• Main Authors: Ferron, Artur Junio Togneri, Jacobsen, Bruno Barcellos, Sant'Ana, Paula Grippa, de Campos, Dijon Henrique Salomé, de Tomasi, Loreta Casquel, Luvizotto, Renata de Azevedo Mello, Cicogna, Antonio Carlos, Leopoldo, André Soares, Lima-Leopoldo, Ana Paula
• Format: Journal Article
• Language: English
• Published: Public Library of Science 21.09.2015
• Subjects: Adrenergic beta receptors; Cardiovascular diseases; Complications and side effects; Genetic aspects; Obesity; Physiological aspects; Risk factors; Brazil
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0138605

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 (Ca.sup.2+) 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].sub.1 AR and [beta].sub.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.