Eicosanoids and control of mesangial cell contraction

Area of Science:

• Nephrology
• Cell Biology
• Pharmacology

Background:

• Glomerular mesangial cell contraction is stimulated by thromboxane A2.
• Prostaglandin (PG) synthesis plays a role in modulating mesangial cell contractile responses.
• PGE2 is the primary arachidonic acid metabolite in mesangial cells.

Purpose of the Study:

• To investigate the role of mesangial prostaglandin synthesis in regulating mesangial cell contraction.
• To determine the effects of nonsteroidal anti-inflammatory drugs (NSAIDs) and exogenous prostaglandins on mesangial cell contractility.

Main Methods:

• Cultured rat mesangial cells were treated with U-46619 (thromboxane A2 analogue).
• Cells were pre-incubated with NSAIDs (indomethacin, acetylsalicylic acid, meclofenamate, piroxicam) to inhibit PGE2 synthesis.
• Effects of exogenous PGE2 and iloprost (PGI2 analogue) were assessed, alongside indomethacin and PGE2 combinations.
• Computer-assisted image analysis microscopy quantified cell contraction.
• Intracellular cyclic AMP (cAMP) accumulation was measured.

Main Results:

• NSAIDs significantly enhanced spontaneous and agonist-induced mesangial cell contraction.
• Exogenous PGE2 and iloprost dose-dependently inhibited U-46619-induced contraction.
• PGE2 reversed the effects of indomethacin and significantly increased intracellular cAMP levels.
• Iloprost also stimulated cAMP accumulation, indicating a cAMP-mediated mechanism.

Conclusions:

• Endogenous arachidonate metabolism, specifically PGE2 synthesis, regulates mesangial cell contraction.
• Inhibition of PGE2 synthesis by NSAIDs potentiates mesangial cell contraction.
• PGE2 and PGI2 exert inhibitory effects on mesangial cell contraction via elevation of intracellular cAMP.