Barbiturates and bradycardia?

Question

Is the actions on GABA receptors the cause of bradycardia which generally happens with barbiturate ODs?

Answer 1

That's correct. Barbiturates potentiate the opening of GABA receptors (which are chloride channels) and cause an overall inhibition of nerve signals in the autonomic ganglia. This results in slower heart beat, reduced respiration, and overall sedation.