Article date: 1991/7/1
PubMed ID: 1946193
Journal name: Pharmacology & toxicology (ISSN: 0901-9928)
Preparations of rat jejunum were tested for their responsiveness to the GABAA receptor agonist, muscimol, and to the haem precursor, delta-aminolaevulinic acid (ALA). Both muscimol (1.0-30 microM) and ALA (1.0 microM-3.0 mM) elicited a concentration-dependent increase in tone. Pretreatment with the GABAA antagonist, bicuculline (10(-5) M), blocked effects of muscimol at all concentrations tested and attenuated effects of 0.3 mM ALA. However, bicuculline enhanced responsiveness of the preparations to ALA at low concentrations (0.01-0.05 microM), as also did picrotoxin (10(-5) M), eliciting a significant increase of tone. The significance of these findings is discussed. This finding of pharmacological activity by ALA at concentrations comparable with its blood levels during acute attacks of intermittent porphyria provides support for the proposal that is may play a role in the aetiology of the gastrointestinal manifestations of this disease.
Author List: Cutler M G, Turner J M, Moore M R
Publication Types: Comparative Study; Journal Article
Substances mentioned in the article: Picrotoxin; Muscimol; Aminolevulinic Acid; Bicuculline;
Mesh terms: Aminolevulinic Acid/antagonists & inhibitors; Animals; Bicuculline/pharmacology; Drug Synergism; In Vitro Techniques; Jejunum/drug effects; Muscimol/antagonists & inhibitors; Muscle Contraction/drug effects; Muscle, Smooth/drug effects; Picrotoxin/pharmacology; Rats; Rats, Inbred Strains;