Faculty Collaboration Database

Effect of ATP on smooth muscle of toad urinary bladder. Arch Int Pharmacodyn Ther 1990;304:93-104

Date

03/01/1990

Pubmed ID

2122823

Scopus ID

2-s2.0-0024989481 (requires institutional sign-in at Scopus site)

Abstract

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.

Author List

Saha JK, Sengupta JN, Koley BN, Koley J

Author

Jyoti N. Sengupta PhD Professor in the Medicine department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Acetylcholine
Adenosine Triphosphate
Animals
Atropine
Bufonidae
Calcium Channel Blockers
Egtazic Acid
Female
In Vitro Techniques
Indomethacin
Male
Muscle Contraction
Muscle, Smooth
Neostigmine
Quinidine
Theophylline
Urinary Bladder