Signal transduction mechanism via adenosine A1 receptor in the cat esophageal smooth muscle cells

• Published in: Cellular signalling 2002-04, Vol.14 (4), p.365-372
• Main Authors: Shim, Jun O., Shin, Chang Yell, Lee, Tai Sang, Yang, Sung Jun, An, Ja Young, Song, Hyun Ju, Kim, Tae Hwan, Huh, In Hoi, Sohn, Uy Dong
• Format: Article
• Language: English
• Subjects: Adenosine; Adenosine - analogs & derivatives; Adenosine - pharmacology; Animals; Calcium Channels; Cats; Cells, Cultured; Contraction; Dose-Response Relationship, Drug; Esophagus - cytology; Esophagus - metabolism; Esophagus - physiology; G protein; GTP-Binding Protein alpha Subunit, Gi2; GTP-Binding Protein alpha Subunits, Gi-Go - metabolism; Heparin - pharmacology; Inositol 1,4,5-Trisphosphate Receptors; Isoenzymes - metabolism; Muscle Contraction - drug effects; Muscle, Smooth - drug effects; Muscle, Smooth - metabolism; Muscle, Smooth - physiology; Pertussis Toxin; Phospholipase; Phospholipase C beta; Phospholipases - metabolism; Proto-Oncogene Proteins - metabolism; Purinergic P1 Receptor Agonists; R-PIA; Receptor; Receptors, Cytoplasmic and Nuclear - antagonists & inhibitors; Receptors, Purinergic P1 - metabolism; Signal Transduction - drug effects; Type C Phospholipases - metabolism; Virulence Factors, Bordetella - pharmacology
• ISSN: 0898-6568; 1873-3913
• DOI: 10.1016/S0898-6568(01)00270-4

We investigated what adenosine receptor type exists and the signaling pathways on the contraction of circular muscle cells isolated by enzymatic digestion from the cat esophagus. Adenosine or the selective A1 receptor agonist R-PIA causes a concentration-dependent contraction. After pretreatment with A1 receptor antagonist, DPCPX, adenosine-mediated contraction was abolished. Adenosine-induced contraction was significantly increased when A1 receptors were preserved by pretreatment with DPCPX followed by inactivation of all unprotected receptors with N-ethylmaleimide. Adenosine- or R-PIA-induced contraction was significantly augmented in the preserved cells and the increase was abolished in the presence of the A1 receptor antagonist DPCPX. PTX abolished contraction induced by adenosine or R-PIA, implying that contraction activated by A1 receptor was coupled to a pertussis toxin (PTX)-sensitive G i protein. After permeabilization, contraction was inhibited by G i2, but not by G i1 and G i3, antibodies. These data suggest that adenosine-induced contraction of esophagus depends on PTX-sensitive G i2. Adenosine- or R-PIA-induced contraction of esophageal smooth muscle cells was not affected by the phospholipase D (PLD) inhibitor ρ-chloromercuribenzoic acid (ρCMB), phospholipase A 2 (PLA 2) inhibitor DEDA or PKC antagonist chelerythrine, but was significantly abolished by phospholipase C (PLC) inhibitor, neomycin. PLC-β3 antibody inhibited R-PIA-induced contraction. R-PIA-induced contraction of esophageal muscle cells was inhibited by IP 3 receptor antagonist heparin, which suggests that the contraction of esophageal smooth muscle cells is dependent on phosphatidylinositol-specific phospholipase (PI-PLC) and IP 3. In conclusion, adenosine- and R-PIA-induced contraction in cat esophageal smooth muscle cell was mediated by A1 receptor. A1 receptor is coupled to PTX-sensitive G protein G i2, which results in the activation of PI-PLC-β3. PI hydrolysis by PI-PLC forms IP 3, which binds to IP 3 receptor on endoplasmic reticulum, resulting in the release of intracellular Ca 2+.