Freire PP, Alves CAB, Deus AFD, Leopoldo APL, Leopoldo AS, Silva DCTD, Tomasi LCD, Campos DHS, Cicogna AC. Obesity does not lead to imbalance between myocardial phospholamban phosphorylation and dephosphorylation.
Arq Bras Cardiol 2014;
103:41-50. [PMID:
25120084 PMCID:
PMC4126760 DOI:
10.5935/abc.20140083]
[Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 02/18/2014] [Indexed: 10/31/2022] Open
Abstract
BACKGROUND
The activation of the beta-adrenergic system promotes G protein stimulation that, via cyclic adenosine monophosphate (cAMP), alters the structure of protein kinase A (PKA) and leads to phospholamban (PLB) phosphorylation. This protein participates in the system that controls intracellular calcium in muscle cells, and it is the primary regulator of sarcoplasmic reticulum calcium pump activity. In obesity, the beta-adrenergic system is activated by the influence of increased leptin, therefore, resulting in higher myocardial phospholamban phosphorylation via cAMP-PKA.
OBJECTIVE
To investigate the involvement of proteins which regulate the degree of PLB phosphorylation due to beta-adrenergic activation in obesity. In the present study, we hypothesized that there is an imbalance between phospholamban phosphorylation and dephosphorylation, with prevalence of protein phosphorylation.
METHODS
Male Wistar rats were randomly distributed into two groups: control (n = 14), fed with normocaloric diet; and obese (n = 13), fed with a cycle of four unsaturated high-fat diets. Obesity was determined by the adiposity index, and protein expressions of phosphatase 1 (PP-1), PKA, PLB, phosphorylated phospholamban at serine16 (PPLB-Ser16) were assessed by Western blot.
RESULTS
Obesity caused glucose intolerance, hyperinsulinemia, hypertriglyceridemia, hyperleptinemia and did not alter the protein expression of PKA, PP-1, PLB, PPLB-Ser16.
CONCLUSION
Obesity does not promote an imbalance between myocardial PLB phosphorylation and dephosphorylation via beta-adrenergic system.
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