These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Thiol group may be involved in the irreversible blockade of presynaptic alpha 2-adrenoreceptors by pyrextramine and benextramine in the isolated guinea pig ileum.
    Author: Brasili L, Cassinelli A, Angeli P, Melchiorre C.
    Journal: Life Sci; 1986 May 05; 38(18):1633-40. PubMed ID: 2871470.
    Abstract:
    This study, conducted on isolated guinea pig ileum, was designed to establish the mechanism of presynaptic alpha 2-adrenoreceptor blockade by the tetramine disulfides, benextramine and pyrextramine. At 1 microM these drugs irreversibly blocked norepinephrine (NE)-induced inhibition of the twitch response to electrical stimulation. This may be the result of covalent bond formation between the disulfide bridge of the inhibitor and a thiol function at the receptor level through an interchange reaction since the benextramine carbon analogue did not affect NE response under the same conditions. Furthermore, NE (10 microM) failed to protect presynaptic alpha 2-adrenoreceptors from pyrextramine blockade whereas idazoxan (O.T microM) completely abolished the irreversible antagonism of pyrextramine (1 microM). This finding suggests that the tetramine disulfide binding site may coincide with that of idazoxan and is different from the NE binding site.
    [Abstract] [Full Text] [Related] [New Search]