Abstract
1. A low concentration of Mn2+ (less than 0.3 mM) transiently enhanced a contractile force (Mn(2+)-induced TC) of the longitudinal muscles of the guinea-pig stomach. 2. The Mn(2+)-induced transient contraction (TC) was not blocked by TTX (10(-7) M) or atropine (10(-6) M), nor by nifedipine (10(-6) M) or D-600 (10(-6) M), but was blocked by Ca2+ removal from the Krebs solution. 3. A preapplication of indomethacin (10(-7) M) completely inhibited an induction of the Mn(2+)-induced TC, but exogenous PGE2 (10(-7) M) was able to induce Mn(2+)-induced TC even with the presence of indomethacin (10(-7) M) and Mn2+ (0.1 mM) in the Krebs solution. 4. Quinacrine (10(-5) M), a phospholipase A2 inhibitor, partially inhibited the Mn(2+)-induced TC. 5. These results suggest that Mn(2+)-induced TC is probably mediated through cyclooxygenase and the subsequent generation of prostaglandin leading to the contraction.
MeSH terms
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Animals
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Atropine / pharmacology
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Calcium / physiology
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Calcium Channel Blockers / pharmacology
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Cyclooxygenase Inhibitors / pharmacology
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Electric Stimulation
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Enzyme Inhibitors / pharmacology
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Female
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Gastric Mucosa / metabolism
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Guinea Pigs
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In Vitro Techniques
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Indomethacin / pharmacology
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Male
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Manganese / antagonists & inhibitors
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Manganese / pharmacology*
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Muscarinic Antagonists / pharmacology
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Muscle Contraction / drug effects
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Muscle, Smooth / drug effects*
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Muscle, Smooth / metabolism*
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Muscle, Smooth / physiology
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Nifedipine / pharmacology
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Phospholipases A / antagonists & inhibitors
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Phospholipases A2
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Prostaglandins / biosynthesis*
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Quinacrine / pharmacology
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Stomach / drug effects
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Stomach / physiology
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Tetrodotoxin / pharmacology
Substances
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Calcium Channel Blockers
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Cyclooxygenase Inhibitors
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Enzyme Inhibitors
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Muscarinic Antagonists
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Prostaglandins
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Manganese
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Tetrodotoxin
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Atropine
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Phospholipases A
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Phospholipases A2
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Quinacrine
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Nifedipine
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Calcium
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Indomethacin