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Cerebral protection with barbiturates: relation to anesthetic effect
Stroke
|March 1, 1978
Summary
Mephobarbital isomers protect against low oxygen by leveraging anesthetic effects, not anticonvulsant properties. This protective effect appears linked to stereospecific receptors, highlighting the importance of molecular structure in drug efficacy.
Area of Science:
- Pharmacology
- Neuroscience
- Biochemistry
Background:
- Hypobaric hypoxia poses a significant physiological challenge.
- Barbiturates are known for their anesthetic and anticonvulsant properties.
- The stereochemistry of drugs can influence their biological activity.
Purpose of the Study:
- To investigate the effect of racemic mephobarbital and its optical isomers on survival time in mice exposed to hypoxia.
- To determine if the protective effect of mephobarbital against hypoxia is linked to its anesthetic or anticonvulsant properties.
Main Methods:
- Mice were exposed to 5% oxygen.
- Survival times were measured for mice treated with racemic mephobarbital, its (-) and (+) isomers, and diazepam.
- Brain concentrations of isomers were analyzed.
Main Results:
- The anesthetically active (-) isomer and racemic mephobarbital significantly increased survival time under hypoxia.
- The inactive (+) isomer did not affect survival time.
- Diazepam reduced convulsions but had a lesser effect on survival time compared to mephobarbital isomers.
- Brain concentrations of isomers were similar, suggesting the protective effect is not due to differential distribution.
Conclusions:
- The protective effect of mephobarbital against hypoxia is directly related to its anesthetic properties, not its anticonvulsant effects.
- A stereospecific receptor interaction is likely involved in both the anesthetic and protective effects of mephobarbital.
- Drug stereochemistry plays a critical role in mediating protective responses to hypoxia.