The intracellular pathway of the acetylcholine‐induced contraction in cat detrusor muscle cells

• Published in: British journal of pharmacology 2002-12, Vol.137 (7), p.1001-1010
• Main Authors: 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
• Format: Article
• Language: English
• Subjects: acetylcholine; Acetylcholine - pharmacology; Alkaloids; Animals; Benzophenanthridines; Biological and medical sciences; calcium; Calcium - metabolism; Calcium - pharmacology; Calcium Channels - physiology; cat bladder; Cats; Cell Size - drug effects; Cell Size - physiology; detrusor; Dose-Response Relationship, Drug; Enzyme Inhibitors - pharmacology; Female; Fundamental and applied biological sciences. Psychology; GTP-Binding Proteins - metabolism; G‐protein; Heparin - pharmacology; Inositol 1,4,5-Trisphosphate Receptors; Isoenzymes - antagonists & inhibitors; Isoenzymes - metabolism; Male; Muscarinic Antagonists - pharmacology; muscarinic receptor; Muscle, Smooth - cytology; Muscle, Smooth - drug effects; Neomycin - pharmacology; p-Chloromercuribenzoic Acid - pharmacology; Phenanthridines - pharmacology; phospholipase C; Phospholipases - antagonists & inhibitors; Phospholipases - metabolism; Protein Kinase C - antagonists & inhibitors; Protein Kinase C - metabolism; Receptors, Cytoplasmic and Nuclear - antagonists & inhibitors; Receptors, Cytoplasmic and Nuclear - physiology; Receptors, Muscarinic - drug effects; Receptors, Muscarinic - physiology; Signal Transduction - drug effects; Signal Transduction - physiology; smooth muscle; Strontium - pharmacology; Thapsigargin - pharmacology; Type C Phospholipases - antagonists & inhibitors; Type C Phospholipases - metabolism; Urinary Bladder - cytology; Urinary Bladder - drug effects; Vertebrates: urinary system
• ISSN: 0007-1188; 1476-5381
• DOI: 10.1038/sj.bjp.0704954

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 M3 muscarinic receptor antagonist ρ‐fluoro‐hexahydrosiladifenidol (ρF‐HSD) but not by the M1 antagonist pirenzepine and the M2 muscarinic receptor antagonist methoctramine. We identified G‐proteins Gq/11, Gs, G0, Gi1, Gi2 and Gi3 in the bladder detrusor muscle. ACh‐induced contraction was selectively inhibited by Gq/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 A2 and protein kinase C did not attenuate the ACh‐induced contraction. ACh‐induced contraction was inhibited by antibody to PLC‐β1 but not PLC‐β3 and PLC‐γ. Thapsigargin or strontium, which depletes or blocks intracellular calcium release, inhibited ACh‐induced contraction. Inositol 1,4,5‐triphosphate (IP3) receptor inhibitor heparin reduced ACh‐induced contraction. These results suggest that in cat detrusor muscle contraction induced by ACh is mediated via M3 muscarinic receptor‐dependent activation of Gq/11 and PLC‐β1 and IP3‐dependent Ca2+ release. British Journal of Pharmacology (2002) 137, 1001–1010. doi:10.1038/sj.bjp.0704954