Effects Of Sulfur Dioxide Derivatives On Ion Channels In Hippocampal Neurons And Cardiomyocytes From Rat

Sulfur dioxide(SO₂), a common pollutant of urban air, can cause and aggravate respiratory tract disease such as tracheitis, asthma, emphysema, and has close relations with lung cancer. Recent studies indicated that SO₂ not only damage respiratory tract but also has toxic effect on many organs in human and animals, and it has been considered a systemic toxicant. In order to further investigate the toxic mechanisms of SO₂ on neuronal and cardiovascular systems, the effects and its might mechanisms of SO₂ derivatives on several ion channels in acutely isolated rat hippocampal neurons and cardiomyocytes were studied using the whole-cell patch clamp technique.The effects of sodium metabisulfite (SMB), as the provider of SO₂ derivatives, on voltage-dependent sodium and potassium channels were examined in rat hippocampal CA1 neurons. The results indicated that SMB enhanced sodium currents (I_Na) in a concentration-dependent manner, significantly shifted the inactivation curve of I_Na to more positive potential, without affecting the activation curve. SMB also significantly shortened the time constant of the recovery I_Na from inactivation, increased the activation and inactivation time constants of I_Na. SMB increased both transient outward potassium current (I_A) and delayed rectifier potassium current (I_k) in a...