Barium enhances the excitability of a motoneurone from the cockroach (Periplaneta americana).
1. An isolated ganglion preparation was used to investigate the effects of barium ions (Ba2+) on excitability of the soma of the 'fast' coxal depressor motoneurone (Df) from the cockroach Periplaneta americana. 2. Under current-clamp, short (50 ms) depolarising pulses applied to the soma of Df elicited damped membrane oscillations in normal external solution. In the presence of 10 mM Ba2+, similar pulses produced all-or-none action potentials (n = 12). 3. Under voltage-clamp, addition of Ba2+ to the external solution suppressed the Ca-dependent K+ conductance (IC) in Df (n = 4). 4. Modulation of IC may offer a means of altering the excitability, and therefore output, of motoneurone Df.
Hancox
J C
JC
Department of Physiology, School of Medical Sciences, University Walk, Bristol, U.K.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001464:Barium / Q000494:pharmacology*; D002118:Calcium / Q000502:physiology; D017952:Ganglia, Invertebrate / Q000166:cytology / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D009046:Motor Neurons / Q000187:drug effects*; D018408:Patch-Clamp Techniques; D010526:Periplaneta / Q000502:physiology*; D015221:Potassium Channels / Q000187:drug effects
D015221:Potassium Channels; D001464:Barium; D002118:Calcium