Stroke, Vol 9, 140-142, Copyright © 1978 by American Heart Association
PA Steen and JD Michenfelder
The effect of racemic mephobarbital and its optical isomers on survival
time of mice exposed to 5% O2 was studied. There was an increase in
survival time from 4.2 minutes to 12.6 minutes for 100 mg/kg of the
anesthetically active (-) isomer and the racemic form, but no increase for
100 mg/kg of the inactive (+) isomer. Since it has been shown that there is
no difference in brain concentrations between the isomers, we conclude that
the barbiturate protective effect is bound to the anesthetic effect. All
mice convulsed, and since the non-anesthetized animals convulsed earlier
and stronger than the anesthetized, it was possible that barbiturate
protection was accounted for by its anticonvulsant effects. Diazepam 7.5
mg/kg, while reducing convulsions to the same degree as barbiturates
without producing anesthesia, only increased survival time to 6.2 minutes.
Thus, the barbiturate protective effect is distinct from the anticonvulsant
effect. It seems to be bound to a stereospecific receptor for both
protection and anesthesia.
ARTICLES
Cerebral protection with barbiturates: relation to anesthetic effect
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