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Obesity does not lead to imbalance between myocardial phospholamban phosphorylation and dephosphorylation.

Freire PP, Alves CA, Deus AF, Leopoldo AP, Leopoldo AS, Silva DC, Tomasi LC, Campos DH, Cicogna AC - Arq. Bras. Cardiol. (2014)

Bottom Line: In the present study, we hypothesized that there is an imbalance between phospholamban phosphorylation and dephosphorylation, with prevalence of protein phosphorylation.Obesity caused glucose intolerance, hyperinsulinemia, hypertriglyceridemia, hyperleptinemia and did not alter the protein expression of PKA, PP-1, PLB, PPLB-Ser16.Obesity does not promote an imbalance between myocardial PLB phosphorylation and dephosphorylation via beta-adrenergic system.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Clínica Médica, Faculdade de Medicina de Botucatu, Universidade Estadual Paulista, Botucatu, SP, Brazil.

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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Related in: MedlinePlus

Glucose tolerance test in control (n = 14) and obese animals (n =13). Data expressed as mean standard-deviation. Analysis of variance(ANOVA) for the model of repeated measures in independent groups,complemented by the Bonferroni test. * p < 0.05 × C.
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f04: Glucose tolerance test in control (n = 14) and obese animals (n =13). Data expressed as mean standard-deviation. Analysis of variance(ANOVA) for the model of repeated measures in independent groups,complemented by the Bonferroni test. * p < 0.05 × C.

Mentions: Figure 4 shows the results of theglucose tolerance test performed in groups C and Ob. Glycemic levels weresimilar at the baseline between groups. After the intraperitonealadministration of glucose, glycemia was high in the Ob group and in moments15, 30, 60 and 90 in comparison to group C.


Obesity does not lead to imbalance between myocardial phospholamban phosphorylation and dephosphorylation.

Freire PP, Alves CA, Deus AF, Leopoldo AP, Leopoldo AS, Silva DC, Tomasi LC, Campos DH, Cicogna AC - Arq. Bras. Cardiol. (2014)

Glucose tolerance test in control (n = 14) and obese animals (n =13). Data expressed as mean standard-deviation. Analysis of variance(ANOVA) for the model of repeated measures in independent groups,complemented by the Bonferroni test. * p < 0.05 × C.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4126760&req=5

f04: Glucose tolerance test in control (n = 14) and obese animals (n =13). Data expressed as mean standard-deviation. Analysis of variance(ANOVA) for the model of repeated measures in independent groups,complemented by the Bonferroni test. * p < 0.05 × C.
Mentions: Figure 4 shows the results of theglucose tolerance test performed in groups C and Ob. Glycemic levels weresimilar at the baseline between groups. After the intraperitonealadministration of glucose, glycemia was high in the Ob group and in moments15, 30, 60 and 90 in comparison to group C.

Bottom Line: In the present study, we hypothesized that there is an imbalance between phospholamban phosphorylation and dephosphorylation, with prevalence of protein phosphorylation.Obesity caused glucose intolerance, hyperinsulinemia, hypertriglyceridemia, hyperleptinemia and did not alter the protein expression of PKA, PP-1, PLB, PPLB-Ser16.Obesity does not promote an imbalance between myocardial PLB phosphorylation and dephosphorylation via beta-adrenergic system.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Clínica Médica, Faculdade de Medicina de Botucatu, Universidade Estadual Paulista, Botucatu, SP, Brazil.

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.

Show MeSH
Related in: MedlinePlus