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EVIDENCE FOR THE PRESENCE OF BOTH P 1 AND P 2 PURINOCEPTORS IN THE RAT MYOMETRIUM
Author(s) -
Gillman Tracey A.,
Pennefather Jocelyn N.
Publication year - 1998
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.1998.tb02257.x
Subject(s) - adenosine , purinergic receptor , medicine , endocrinology , potency , agonist , myometrium , adenosine receptor , antagonist , stimulation , biology , adenosine triphosphate , chemistry , uterus , receptor , biochemistry , in vitro
SUMMARY 1. Adenosine, adenosine triphosphate (ATP) and some stable analogues of adenosine inhibited field stimulation‐induced contractions of the uterus from rats treated with oestradiol cypionate (20 μg/kg, s.c.) 1 day previously. Adenosine was twice as potent as ATP; both were potentiated by dipyridamole (10 μmol/L). 2. The order of agonist potency of adenosine and its analogues was: 5′‐ N ‐ethyIcarboxamidoadenosine (NECA) > N 6 ‐cyclohexyl‐adenosine ≥ R‐phenylisopropyladenosine = s‐phenylisopropyl‐adenosine = 2‐chIoroadenosine ≥ adenosine ≥ ATP ≫ 2‐ p ‐(2‐carboxyethyl) phenethylarnino‐5′‐ N ‐ethylcarboxamido‐adenosine. This order suggests the presence of P 1 purinoceptors of the A 2B subtype. 3. Responses to agonists were antagonized to differing extents by the P1 purinoceptor antagonist 8‐phenyltheophylline (10μ‐mol/L). 4. In uterine preparations from rats pretreated for 2 days with oestrogen (20 μg/kg, s.c.) and for 1 day with progesterone (3 mg/animal, s.c), the inhibitory potencies of adenosine and NECA were reduced, indicating hormonal regulation of uterine responsiveness to P 1 purinoceptor agonists. 5. Stable analogues of ATP caused contractions of unstimulated myometrial preparations from oestrogen‐treated animals, indicating activation of a P 2 purinoceptor, possibly of the P 2x subtype, because the relative order of potency was α,β‐methylene ATP> β, γ‐methylene ATP = ATP = 2‐methylthioATP.