Effects of medazepam on voltage-gated ion currents of cultured chick sensory neurons.
The effects of the benzodiazepine, medazepam, were investigated in current and voltage-clamped cultured chick dorsal root ganglion neurons. Under current clamp, micromolar concentrations initially elevated the action potential threshold and blocked both the sodium and calcium components of the spike. In voltage clamp, low (I(Ca.T)) and high (I(CA.N/L)) threshold calcium, sodium (I(Na)) and the delayed rectifier potassium (I(K)) currents were isolated by the use of appropriate solutions and voltage command protocols. Medazepam depressed both subtypes of I(Ca) equally well with calculated half-maximal depression at 77 microM. At a fixed concentration of 200 microM, medazepam depressed I(Na) (70 +/- 9%) and I(K) (73 +/- 6%) to a degree comparable to I(Ca) (75 +/- 3%). The results show that benzodiazepines can modulate the activity of several voltage-gated ion currents in chick dorsal root ganglion neurons.
D000818:Animals; D014151:Anti-Anxiety Agents / Q000494:pharmacology*; D002478:Cells, Cultured; D002642:Chick Embryo; D004594:Electrophysiology; D007473:Ion Channels / Q000187:drug effects*; D008472:Medazepam / Q000494:pharmacology*; D009475:Neurons, Afferent / Q000187:drug effects / Q000378:metabolism*
D014151:Anti-Anxiety Agents; D007473:Ion Channels; D008472:Medazepam