Effect of metformin on insulin-resistant endothelial cell function

Area of Science:

• Endothelial cell biology
• Metabolic disorders
• Pharmacology

Background:

• Insulin resistance (IR) impairs endothelial cell function, contributing to cardiovascular complications.
• Endothelial dysfunction is characterized by reduced nitric oxide (NO) bioavailability and increased endothelin-1 (ET-1) levels.
• Metformin is a widely used drug for type 2 diabetes, but its direct effects on IR endothelial cells require further elucidation.

Purpose of the Study:

• To investigate the therapeutic effects of metformin on insulin-resistant (IR) endothelial cells.
• To determine the impact of metformin on nitric oxide (NO) and endothelin-1 (ET-1) levels in IR endothelial cells.
• To assess the effect of metformin on endothelial nitric oxide synthase (eNOS) protein expression in IR endothelial cells.

Main Methods:

• Established an in vitro model of IR endothelial cells using glucose, dexamethasone, and insulin.
• Quantified nitric oxide (NO) production via nitroreductase activity.
• Measured endothelin-1 (ET-1) concentration using enzyme-linked immunosorbent assay (ELISA).
• Determined endothelial nitric oxide synthase (eNOS) protein expression through western blotting.

Main Results:

• Optimal conditions for inducing IR in endothelial cells were identified (10⁻⁴ mmol/l insulin, 30 mM glucose, 1 μM dexamethasone for 48 h).
• Metformin treatment significantly increased NO content and decreased ET-1 concentration in IR cells (P<0.05).
• Metformin significantly enhanced intracellular eNOS protein expression in IR endothelial cells (P<0.05), with an optimal concentration of 10⁻³ mmol/l.

Conclusions:

• Metformin effectively improves the function of insulin-resistant endothelial cells.
• The beneficial effects of metformin are associated with increased NO production and eNOS protein expression.
• Metformin may serve as a potential therapeutic agent for endothelial dysfunction in insulin-resistant states.