title: Identification of purinoceptors in the isolated stomach and intestine of the three-spined stickleback Gasterosteus aculeatus L.
abstract: 1. Adenine nucleosides and nucleotides were examined for pharmacological activity in isolated stomach and intestine from the stickleback Gasterosteus aculeatus L. 2. Adenosine and its stable analogues all concentration-dependently relaxed carbachol-contracted stomach and intestine, with no significant difference in the potency of the analogues. Only 8-(p-sulphophenyl) theophylline inhibited the relaxant response to adenosine in both tissues; other adenosine antagonists such as 1,3-dipropyl-8-cyclopentylxanthine were not active. 3. ATP, alpha, beta-methylene ATP (alpha, beta-MeATP) and 2-methylthio ATP (2-MeSATP) all caused concentration-dependent contractions of the stomach and intestine. 4. In the stomach, the order of potency was 2-MeSATP > alpha,beta-MeATP = ATP; the P2Y-purinoceptor antagonist reactive blue 2 inhibited responses to ATP. 5. In the intestine, the order of potency was alpha,beta-MeATP > 2-MeSATP = ATP; reactive blue 2 did not affect responses to ATP, nor did prolonged incubation with alpha,beta-MeATP. 6. It is concluded that in both the stomach and intestine, adenosine is acting through a non-specific or undifferentiated P1-purinoceptor. In the stomach, however, the P2-purinoceptor appears to be analogous to the mammalian P2Y-purinoceptor, and in the intestine, the receptor is more similar to the mammalian P2X-subtype, although it was not susceptible to desensitization.
authors.affiliation: Department of Anatomy and Developmental Biology, University College London.
authors.forename: G E
authors.initials: GE
authors.lastname: Knight
authors.forename: G
authors.initials: G
authors.lastname: Burnstock
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology*; D000818:Animals; D005399:Fishes; D007422:Intestines / Q000737:chemistry* / Q000187:drug effects; D011983:Receptors, Purinergic / Q000032:analysis*; D013270:Stomach / Q000737:chemistry* / Q000187:drug effects
chemical_list: D011983:Receptors, Purinergic; D000241:Adenosine