Sodium Metabisulfite: Effects on Ionic Currents and Excitotoxicity.

Area of Science:

• Neuroscience
• Cardiology
• Toxicology
• Food Science

Background:

• Sodium metabisulfite (SMB) is a widely used food preservative and antioxidant.
• The mechanisms by which SMB affects cellular excitability and induces excitotoxicity are not fully understood.
• Electrically excitable cells, such as neurons and cardiomyocytes, are crucial for physiological functions.

Purpose of the Study:

• To investigate the electrophysiological effects of SMB on HL-1 cardiomyocytes and NSC-34 neurons.
• To explore the relationship between SMB exposure, pilocarpine-induced seizures, and neuronal excitotoxicity in rats.
• To analyze the impact of chronic SMB treatment on sodium channel expression.

Main Methods:

• Patch-clamp technique to record electrophysiological effects on cardiomyocytes and neurons.
• Western blotting to assess sodium channel expression in rat hippocampi.
• In vivo studies using pilocarpine to induce seizures in SMB-treated rats.

Main Results:

• SMB (30 μM) stimulated voltage-gated Na+ current (I Na) and slowed its inactivation in HL-1 cells.
• SMB inhibited the tail component of the rapidly activating delayed-rectifier K+ current (I Kr) dose-dependently.
• SMB treatment exacerbated pilocarpine-induced seizures, increased neuronal damage, and promoted mossy fiber sprouting in rats, correlating with increased sodium channel expression.

Conclusions:

• Sodium metabisulfite alters cellular excitability by activating sodium channels, potentially contributing to excitotoxicity.
• SMB affects a wide spectrum of excitable cells, including cardiac and neuronal cells.
• The findings suggest SMB's role in neurotoxic mechanisms and seizure susceptibility.