The cytokine TNF-alpha is known to play an important role in the genesis of neuropathic pain by inducing spontaneous neuronal activity after a peripheral nerve lesion. Still, in which way exactly TNF-alpha causes spontaneous activity is yet to be discovered. Therefore, we have focused on examining the influence of TNF- alpha on voltage-gated potassium, calcium and sodium channels and the membrane conductance in nociceptive DRG neurones. Currents were recorded by whole cell patch clamp with small dorsal root ganglion neuronal cells from rats using the adequate solutions for the respective channel current isolation. TNF-alpha was applied in a concentration of 100ng/ml.

Voltage-gated calcium and potassium channel currents are unchanged by application of TNF-alpha. Voltage-gated sodium channels currents were unchanged in 57% of the cells, while in 43% an increase of the current of 7%± 4% occurred after application. The IV-ramps uncovered a decrease of 15%± 12% of the membrane conductance after application TNF-alpha at a depolarisation of +20mV. Therefore, we assume that TNF-alpha acutely modulates the membrane conductance by interfering with non-voltage-gated potassium channels.