Sodium Pentobarbital?

[Danielle B]

How does it put animals "to sleep"? I mean I know it does something to stop the heart but what is the mode of action? I work at vet clinic as a secretary to file paperwork and I sometimes have to file papers about an animal being euthanized (which we do by two injections; the first being Ketamine that knocks them out, then the Sodium Pentobarbital) and I find it real awkward to talk to the technicians, so I'm wondering, what does the drug do to make animals transition peacefully to "Rainbow Bridge"?

[abacaxitoo]

It depresses their respiration ... technically they have brain death because of the lack of oxygen, which in turn stops the heart. The large doses used by vets might affect the heart, but it's the lack of breathing that is the primary cause of death.

The ketamine increases the effectof the barbiturate, as would alcohol or opiates.

"The principal mechanism of action of barbiturates is believed to be their affinity for the GABAA receptor (Acts on GABA : BDZ receptor cl- channel complex). GABA is the principal inhibitory neurotransmitter in the mammalian Central Nervous System (CNS). Barbiturates bind to the GABAA receptor at the alpha subunit, which are binding sites distinct from GABA itself and also distinct from the benzodiazepine binding site. Like benzodiazepines, barbiturates potentiate the effect of GABA at this receptor. In addition to this GABA-ergic effect, barbiturates also block the AMPA receptor, a subtype of glutamate receptor. Glutamate is the principal excitatory neurotransmitter in the mammalian CNS. Taken together, the findings that barbiturates potentiate inhibitory GABAA receptors and inhibit excitatory AMPA receptors can explain the CNS-depressant effects of these agents. At higher concentration they inhibit the Ca2+ dependent release of neurotransmitters."