Korean J Gastroenterol.  2000 May;35(5):539-545.

Effects of Ca2+ Antagonists and Protein Kinase Inhibitors on Ethanol-Induced Contraction of Cat Gastric Smooth Muscle

Abstract

BACKGROUND/AIMS
The mechanism of ethanol in contraction of gastric smooth muscle still remains unclear. To investigate underlying mechanism of ethanol in tonic contraction, we measured isometric contractions of cat gastric smooth muscle using various Ca2+antagonists and protein kinase inhibitors.
METHODS
Circular muscle strips (2.0x0.2 cm) were prepared from the fundus of stomach to measure isometric contraction, and their contractions were recorded in a cylinder-shaped chamber filled with Krebs-Ringer solution (pH 7.4, temperature 36C degrees) bubbled with 5% CO2 in O2.
RESULTS
Ethanol induced tonic contraction in a dose-dependent manner. EGTA inhibited dose-dependently the contraction induced by 2% ethanol. Ethanol-induced contraction was not inhibited by verapamil, diltiazem or TMB-8. However, econazole (a blocker of receptor-operated Ca2+channel) significantly inhibited ethanol-induced contraction. Ethanol-induced contraction was significantly inhibited by 10 micrometer bisindolylmaleimide and 50 micrometer genistein, but not by 50 micrometer W-7 and 30 micrometer trifluoperazine. One micrometer PMA (Protein kinase C activator) augmented ethanol-induced contraction, whereas tyrosine phosphatase inhibitors such as BTH, BPA and vanadate, did not.
CONCLUSIONS
From the above results, it is suggested that ethanol-induced contraction is mediated by protein kinase C and tyrosine kinase, and the influx of extracellular Ca2+ induced by ethanol is mediated via econazole-sensitive Ca2+channel.

Keyword

Ethanol; Protein kinase C; Tyrosine kinase; Smooth muscle contraction; Econazole

MeSH Terms

Animals
Cats*
Diltiazem
Econazole
Egtazic Acid
Ethanol
Genistein
Isometric Contraction
Muscle, Smooth*
Phosphotransferases
Protein Kinase C
Protein Kinase Inhibitors*
Protein Kinases*
Protein-Tyrosine Kinases
Stomach
Trifluoperazine
Tyrosine
Vanadates
Verapamil
Diltiazem
Econazole
Egtazic Acid
Ethanol
Genistein
Phosphotransferases
Protein Kinase C
Protein Kinase Inhibitors
Protein Kinases
Protein-Tyrosine Kinases
Trifluoperazine
Tyrosine
Vanadates
Verapamil
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