Role of myosin light-chain kinase and protein kinase C in pepsinogen secretion from guinea pig gastric chief cells in monolayer culture.
We evaluated the role of myosin light-chain kinase (MLCK) and protein kinase C (PKC) in pepsinogen secretion from guinea pig gastric chief cells using a monolayer culture system of chief cells and an enzyme immunoassay system for guinea pig pepsinogen. An MLCK inhibitor, 1-(5-chloronaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine (ML-9), significantly inhibited both the basal pepsinogen secretion and the secretion by carbamylcholine chloride (carbachol) or ionomycin without affecting intracellular free Ca2+ concentration ([Ca2+]i), but not by 12-O-tetradecanoylphorbol-13- acetate (TPA) or forskolin. A PKC inhibitor, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7), significantly reduced the pepsinogen secretion by carbachol or TPA, but not by forskolin or ionomycin, and did not affect the basal secretion and the [Ca2+]i elevated by carbachol or ionomycin. We concluded that: (1) MLCK plays an important role in basal and drug-stimulated pepsinogen secretion, (2) MLCK is involved in the Ca(2+)-dependent intracellular pathway but not in the cyclic adenosine monophosphate (cAMP) dependent pathway, (3) PKC is irrelevant to activation of MLCK, and (4) increases in cAMP and [Ca2+]i are independent of activation of PKC.
Okayama
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N
First Department of Internal Medicine, Nagoya City University Medical School, Japan.
Joh
T
T
Miyamoto
T
T
Kato
T
T
Itoh
M
M
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000818:Animals; D001381:Azepines / Q000494:pharmacology; D002118:Calcium / Q000502:physiology; D002217:Carbachol / Q000494:pharmacology; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D005753:Gastric Mucosa / Q000166:cytology* / Q000378:metabolism; D006168:Guinea Pigs; D007124:Immunoenzyme Techniques; D015759:Ionomycin / Q000494:pharmacology; D007546:Isoquinolines / Q000494:pharmacology; D008297:Male; D008854:Microscopy, Electron; D009219:Myosin-Light-Chain Kinase / Q000037:antagonists & inhibitors / Q000502:physiology*; D010435:Pepsinogens / Q000378:metabolism*; D010879:Piperazines / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D011817:Rabbits; D013268:Stimulation, Chemical; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D001381:Azepines; D007546:Isoquinolines; D010435:Pepsinogens; D010879:Piperazines; C056218:ML 9; D005576:Colforsin; D015759:Ionomycin; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D002217:Carbachol; D011493:Protein Kinase C; D009219:Myosin-Light-Chain Kinase; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium