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Postnatal changes in response to adenosine and adenine nucleotides in rat duodenum
Author(s) -
Furukawa Kyoko,
Nomoto Teruko
Publication year - 1989
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1989.tb12568.x
Subject(s) - adenosine , guanethidine , tetrodotoxin , medicine , endocrinology , adenosine monophosphate , adenine nucleotide , purinergic receptor , chemistry , biology , nucleotide , biochemistry , stimulation , gene
1 The effects of adenosine and adenine nucleotides were studied in rat duodenum from postnatal day 1 to day 70. The mechanical activity of duodenal segments was recorded through an isotonic transducer connected to a polygraphic recorder. 2 In rat duodenal segments, adenosine‐5′‐triphosphate (ATP, 10 −4 m ) and adenosines‐5′‐diphosphate (ADP, 10 −4 m ) produced a contractile response on postnatal day 1. This response increased with age, peaking on day 7, followed by a gradual decrease and was non‐existent by day 21. In contrast, a relaxant response to ATP and ADP was apparent on day 21, and continued to increase up to day 70. 3 The contraction caused by ATP was inhibited by indomethacin or the P 2y ‐purinoceptor antagonist, reactive blue‐2 but not by tetrodotoxin or hyoscine. Thus, it may be mediated by production of prostaglandin through the P 2y ‐purinoceptor. The relaxation produced by ATP was inhibited by reactive blue‐2 but not by tetrodotoxin, guanethidine or the P 1 ‐purinoceptor antagonist, 8‐phenyltheophylline indicating that ATP acts on smooth muscle directly through the P 2y ‐purinoceptor. The pD 2 for the contractile response to ATP was 5.15 on day 7 and that for the relaxant response, 6.64 on day 70. 4 Adenosine (10 −4 m ) and adenosine‐5′‐monophosphate (AMP, 10 −4 m ) elicited no response before day 14. On day 14, both adenosine and AMP produced a small relaxant response which increased with age. The relaxation produced by adenosine was inhibited by 8‐phenyltheophylline but not by tetrodotoxin or guanethidine, indicating that it is mediated by an action on the P 1 ‐purinoceptor of smooth muscle. 5 It is evident from these results that in neonatal rat, a contractile response to ATP and ADP occurs initially in the duodenum, followed by a relaxant response to adenosine and AMP on day 14 and to ADP and ATP on day 21. 6 The smooth muscle of rat duodenum may tentatively be concluded to contain separate purinoceptors for adenosine and AMP (P 1 ) and ADP and ATP (P 2 ) and the responses to P 1 ‐ and P 2 ‐agonists change during the course of development.