mechanism of barbiturate anesthesia

[Kurt Franklin Ahrens]

In our lab, when we perform chronic electrode placement surgery on
rats, we use sodium pentobarbital (Nembutal) as the anesthetic.  My
question is by what mechanism(s) does this chemical act?  I would like
references on its effects on the neuronal membrane, signal propagation, 
and synaptic transmission.  Thanks in advance.  

Kurt F. Ahrens (kurt at uclink.berkeley.edu)
Division of Neurobiology in the Department of Molecular and Cell Biology
UC Berkeley