Obesity and hyperinsulinemia drive adipocytes to activate a cell cycle program and senesce.

Obesity is considered an important factor for many chronic diseases, including diabetes, cardiovascular disease and cancer. The expansion of adipose tissue in obesity is due to an increase in both adipocyte progenitor differentiation and mature adipocyte cell size. Adipocytes, however, are thought to be unable to divide or enter the cell cycle.

Negative regulation of glucose metabolism in human myotubes by supraphysiological doses of 17β-estradiol or testosterone.

Objective: Exposure of skeletal muscle to high levels of testosterone or estrogen induces insulin resistance, but evidence regarding the direct role of either sex hormone on metabolism is limited. Therefore, the aim of this study was to investigate the direct effect of acute sex hormone exposure on glucose metabolism in skeletal muscle.

Materials/methods: Differentiated human skeletal myotubes were exposed to either 17β-estradiol or testosterone and metabolic characteristics were assessed.

Mitochondrial regulators of fatty acid metabolism reflect metabolic dysfunction in type 2 diabetes mellitus.

The delicate homeostatic balance between glucose and fatty acid metabolism in relation to whole-body energy regulation is influenced by mitochondrial function. We determined expression and regulation of mitochondrial enzymes including pyruvate dehydrogenase kinase (PDK) 4, PDK2, carnitine palmitoyltransferase 1b, and malonyl-coenzyme A decarboxylase in skeletal muscle from people with normal glucose tolerance (NGT) or type 2 diabetes mellitus (T2DM). Vastus lateralis biopsies were obtained from NGT (n = 79) or T2DM (n = 33) men and women matched for age and body mass index.

Endothelin-1 reduces glucose uptake in human skeletal muscle in vivo and in vitro.

Objective: Endothelin (ET)-1 is a vasoconstrictor and proinflammatory peptide that may interfere with glucose uptake. Our objective was to investigate whether exogenous ET-1 affects glucose uptake in the forearm of individuals with insulin resistance and in cultured human skeletal muscle cells.

Research Design And Methods: Nine male subjects (aged 61 ± 3 years) with insulin resistance (M value <5.

Testosterone or 17{beta}-estradiol exposure reveals sex-specific effects on glucose and lipid metabolism in human myotubes.

Changes in sex hormone levels with aging or illness may lead to metabolic disorders. Moreover, the ratio changes in men versus women may have distinct pathological responses. Since little is known about sex hormone action on muscle metabolism, we examined the role of testosterone or 17β-estradiol (E(2)) in metabolism and investigated whether either hormone may mediate a sex-specific effect.

Regulation of glucose uptake by endothelin-1 in human skeletal muscle in vivo and in vitro.

Context: Expression of the vasoconstrictor and proinflammatory peptide endothelin (ET)-1 is increased in insulin-resistant (IR) subjects.

Objective: The aim of this study was to investigate whether ET-1 regulates skeletal muscle glucose uptake in IR subjects in vivo and in cultured human skeletal muscle cells.

Design And Participants: Eleven subjects participated in three protocols using brachial artery infusion of: A) BQ123 (10 nmol/min) and BQ788 (10 nmol/min) (ET(A) and ET(B) receptor antagonist, respectively), followed by coinfusion with insulin (0.

Glucocorticoid-mediated effects on metabolism are reversed by targeting 11 beta hydroxysteroid dehydrogenase type 1 in human skeletal muscle.

Background: Adipose tissue and liver play important roles in mediating the metabolic actions of glucocorticoids. However, the effects of glucocorticoids on glucose and lipid metabolism in skeletal muscle are not understood completely. Intracellular glucocorticoid action is dependent on 11 beta-hydroxysteroid dehydrogenase 1 (HSD1), an enzyme that converts cortisone to active cortisol.

Adiponectin protects against myocardial ischaemia-reperfusion injury via AMP-activated protein kinase, Akt, and nitric oxide.

Aims: Cardiovascular disease and type 2 diabetes mellitus are associated with low plasma concentration of adiponectin. The aim of this study was to investigate whether adiponectin exerts cardioprotective effects during myocardial ischaemia-reperfusion and whether this effect is related to the production of nitric oxide (NO).

Methods And Results: Isolated rat hearts were subjected to 30 min of either global or local ischaemia followed by 60 min of reperfusion.