Document Detail


Effect of ATP on smooth muscle of toad urinary bladder.
MedLine Citation:
PMID:  2122823     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Adenosine 5'-triphosphate (ATP), at a dose range of 1.8 to 116 microM, produced an initial phasic contraction followed by a rhythmic contraction in urinary bladder smooth muscle of the toad (Bufo melanostictus). Acetylcholine produced a rhythmic contraction which was antagonized by atropine (1.5 microM) and potentiated by neostigmine (1.7 microM), indicating activation of muscarinic receptors. However, both phasic and rhythmic components of ATP contraction were atropine-resistant. Quinidine (26-264 M) abolished the responses to ATP and acetylcholine, while indomethacin (28 microM) and theophylline (55 microM) antagonized only the acetylcholine responses. Repeated application of alpha, beta-methylene ATP desensitized the receptors and completely abolished contraction. ATP did not produce a phasic contraction in alpha, beta-methylene ATP-desensitized tissue, indicating that both ATP and its alpha, beta-methylene analogue occupy the same receptor site for phasic contraction. On the other hand, the rhythmic contraction induced by ATP remained unaffected in alpha, beta-methylene ATP-treated tissue. The phasic contraction in response to ATP can be blocked by verapamil (4 microM), but rhythmic contraction can only be abolished by a high concentration of verapamil (16 microM). Moreover, ATP produced no response in Ca+(+)-free or EGTA-containing solution, showing thereby that contractile responses to ATP are dependent upon extracellular Ca(+)+. These results indicate that the phasic component is a P2x-receptor-activated response while the rhythmic component might be an opening of calcium ion channels, either by depolarization of the membrane or by some unknown mechanism.
Authors:
J K Saha; J N Sengupta; B N Koley; J Koley
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Archives internationales de pharmacodynamie et de thérapie     Volume:  304     ISSN:  0003-9780     ISO Abbreviation:  Arch Int Pharmacodyn Ther     Publication Date:    1990 Mar-Apr
Date Detail:
Created Date:  1990-12-27     Completed Date:  1990-12-27     Revised Date:  2012-01-12    
Medline Journal Info:
Nlm Unique ID:  0405353     Medline TA:  Arch Int Pharmacodyn Ther     Country:  BELGIUM    
Other Details:
Languages:  eng     Pagination:  93-104     Citation Subset:  IM    
Affiliation:
Department of Physiology, University College of Science, University of Calcutta, India.
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MeSH Terms
Descriptor/Qualifier:
Acetylcholine / pharmacology
Adenosine Triphosphate / analogs & derivatives,  pharmacology*
Animals
Atropine / pharmacology
Bufonidae
Calcium Channel Blockers / pharmacology
Egtazic Acid / pharmacology
Female
Indomethacin / pharmacology
Male
Muscle Contraction / drug effects
Muscle, Smooth / drug effects*
Neostigmine / pharmacology
Quinidine / pharmacology
Theophylline / pharmacology
Urinary Bladder / drug effects
Chemical
Reg. No./Substance:
0/Calcium Channel Blockers; 51-55-8/Atropine; 51-84-3/Acetylcholine; 53-86-1/Indomethacin; 56-54-2/Quinidine; 56-65-5/Adenosine Triphosphate; 58-55-9/Theophylline; 59-99-4/Neostigmine; 67-42-5/Egtazic Acid; 7292-42-4/alpha,beta-methyleneadenosine 5'-triphosphate

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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