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Contractor effect of barbiturates on smooth muscle
Archives Internationales De Pharmacodynamie Et De Therapie
|October 1, 1975
Summary
Certain convulsant barbiturates, unlike others, contract isolated rabbit tissues. This contractor effect, seen in lethal seizure-inducing barbiturates, is independent of adrenergic mechanisms and linked to their stimulant properties.
Area of Science:
- Pharmacology
- Neuroscience
Background:
- Barbiturates are known for their central nervous system effects, including seizure induction.
- Understanding the peripheral actions of barbiturates is crucial for a comprehensive pharmacological profile.
Purpose of the Study:
- To investigate the in vitro contractor effects of various barbiturates on different isolated rabbit tissues.
- To differentiate the contractile responses based on the in vivo seizure patterns elicited by the barbiturates.
Main Methods:
- In vitro testing of rabbit jejunal segments, aortic strips, and tracheal chains.
- Exposure to four different convulsant barbiturates, thiopental, methohexital, and pentobarbital.
- Assessment of contractile responses and their modulation by phenoxybenzamine, norepinephrine, acetylcholine, and histamine.
Main Results:
- Two convulsant barbiturates inducing lethal tonic seizures contracted all tested tissues.
- Two convulsant barbiturates inducing non-lethal clonic seizures showed no contractor effect.
- Methohexital and pentobarbital also lacked contractor effects.
- Contractile effects of lethal seizure-inducing barbiturates on aortic strips were independent of adrenergic and other receptor mechanisms.
Conclusions:
- A specific group of convulsant barbiturates exhibits potent in vitro contractor effects on various tissues.
- These contractor effects are associated with lethal tonic seizures and appear independent of adrenergic pathways.
- Structural similarities and stimulant potency may correlate with these distinct pharmacological actions.
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