Effects Of SO₂ Derivatives And Lead On Ion Channel Currents In Acutely Isolated Rat Neurons

Dorsal root ganglion (DRG) neurons are primary sensory neurons. One of the main functional properties of DRG neurons is relay function between sensors and central neurons. Each neuron in the DRG transduces synaptic input into a temporal code of action potentials, a code suitable for sending the information to other neurons of the spinal cord or to the central nucleus. DRG neurons can conduct high-frequency repetitive action potentials from the periphery to spinal cord motoneurons or to the central nucleus without significant delay. Hippocampus is main part of study memory. If the hippocampus is damnified, the capacity of study memory is damaged. SO₂ derivatives and lead were neuronal toxin. So we studied the effects of SO₂ derivatives and lead on ion channel currents in acutely isolated DRG neurons and hippocampal neurons. The results as follows:SO₂ derivatives reversibly increased the amplitudes of potassium currents in a concentration-dependent and voltage-dependent. SO₂ derivatives significantly shifted the activation of delayed rectifier potassium current in the hyperpolarizing direction and shifted the inactivation curve of transient outward potassium currents in the depolarizing direction. 50% enhanced concentration (IC₅₀) of SO₂ derivatives in DRG neurons was about 35.8μM in transient outward potassium currents and 26.3 μM in delayed rectifier current. These results indicated that SO₂ derivatives increased the amplitudes of potassium currents and changed the properties of potassium channels.SO₂ derivatives on tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant (TTX-R) sodium channels in cultured post-natal dorsal root ganglion (DRG) neurons were either inhibitory or stimulatory depending on the kinetic parameters tested. SO₂ derivatives shifted the conductance-voltage curve for TTX-R sodium currents in the depolarizing direction but had little effect on that for TTX-S sodium currents. The steady-state inactivation curve for TTX-R sodium channel was shifted by SO₂ derivatives in the depolarizing direction as that for TTX-S sodium channel. SO₂ derivatives changed the reversal potential and increased the...