Signal transduction of bombesin-induced circular smooth muscle cell contraction in cat esophagus.
OBJECTIVE
To investigate the mechanism of bombesin-induced circular smooth muscle cell contraction in cat esophagus.


METHODS
Specific G protein or phospholipase C involved in cat esophagus contraction was identified, muscle cells were permeabilized with saponin. After permeabilization of muscle cells, the Gi3 antibody inhibited bombesin-induced smooth muscle cell contraction.


RESULTS
Incubation of permeabilized circular muscle cells with PLC-beta3 antibody could inhibit bombesin-induced contraction. H-7, chelerythrine (PKC inhibitor) and genistein (protein tyrosine kinase inhibitor) inhibited bombesin-induced contraction, but DAG kinase inhibitor, R59949, could not inhibit it. To examine which mitogen-activated protein kinase (MAPK) was involved in bombesin-induced contraction, the specific MAPK inhibitors (MEK inhibitor, PD98059 and p38 MAPK inhibitor, SB202190) were used. Preincubation of PD98059 blocked the contraction induced by bombesin in a concentration-dependent manner. However, SB202190 had no effects on contraction.


CONCLUSIONS
Bombesin-induced circular muscle cell contraction in cat esophagus is madiated via a PKC or a PTK-dependent pathway or p44/p42 MAPK pathway.
Park
Sung-Uk
SU
Department of Pharmacology, College of Pharmacy, Chung Ang University, Seoul 156-756, Republic of Korea.
Shin
Chang-Yell
CY
Ryu
Jung-Su
JS
La
Hyen-O
HO
Park
Sun-Young
SY
Song
Hyun-Ju
HJ
Min
Young-Sil
YS
Kim
Dong-Seok
DS
Sohn
Uy-Dong
UD
D000818:Animals; D001839:Bombesin / Q000494:pharmacology*; D002415:Cats; D004947:Esophagus / Q000187:drug effects* / Q000502:physiology; D007527:Isoenzymes / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology; D009119:Muscle Contraction / Q000187:drug effects*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000502:physiology; D054799:Phospholipase C beta; D011493:Protein Kinase C / Q000502:physiology; D043562:Receptors, G-Protein-Coupled / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*; D010738:Type C Phospholipases / Q000502:physiology
D007527:Isoenzymes; D043562:Receptors, G-Protein-Coupled; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; D010738:Type C Phospholipases; D054799:Phospholipase C beta; D001839:Bombesin