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The intracellular pathway of the acetylcholine‐induced contraction in cat detrusor muscle cells
Author(s) -
An J Y,
Yun H S,
Lee Y P,
Yang S J,
Shim J O,
Jeong J H,
Shin C Y,
Kim J H,
Kim D S,
Sohn U D
Publication year - 2002
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 - 10.1038/sj.bjp.0704954
Subject(s) - acetylcholine , detrusor muscle , muscle contraction , contraction (grammar) , intracellular , chemistry , microbiology and biotechnology , smooth muscle , anatomy , medicine , endocrinology , biology
The present study was aimed to investigate intracellular pathways involved in acetylcholine (ACh)‐induced contraction in cat detrusor muscle cells Contraction was expressed as per cent shortening of length of individually isolated smooth muscle cells obtained by enzymatic digestion. Dispersed intact and permeabilized cells were prepared for the treatment of drugs and antibody to enzymes, respectively. Using Western blot, we confirmed the presence of related proteins. The maximal contraction to ACh was generated at 10 −11 M . This response was preferentially antagonized by M 3 muscarinic receptor antagonist ρ‐fluoro‐hexahydrosiladifenidol (ρF‐HSD) but not by the M 1 antagonist pirenzepine and the M 2 muscarinic receptor antagonist methoctramine. We identified G‐proteins G q/11 , G s , G 0 , G i1 , G i2 and G i3 in the bladder detrusor muscle. ACh‐induced contraction was selectively inhibited by G q/11 antibody but not to other G subunit. The phosphatidylinositol‐specific phospholipase C (PI‐PLC) inhibitor neomycin reduced ACh‐induced contraction. However, the inhibitors of the phospholipase D, the phospholipase A 2 and protein kinase C did not attenuate the ACh‐induced contraction. ACh‐induced contraction was inhibited by antibody to PLC‐β 1 but not PLC‐β 3 and PLC‐γ. Thapsigargin or strontium, which depletes or blocks intracellular calcium release, inhibited ACh‐induced contraction. Inositol 1,4,5‐triphosphate (IP 3 ) receptor inhibitor heparin reduced ACh‐induced contraction. These results suggest that in cat detrusor muscle contraction induced by ACh is mediated via M 3 muscarinic receptor‐dependent activation of G q/11 and PLC‐β 1 and IP 3 ‐dependent Ca 2+ release.British Journal of Pharmacology (2002) 137 , 1001–1010. doi: 10.1038/sj.bjp.0704954