Inhibitory effect of okadaic acid on noradrenaline exocytosis from guinea-pig vas deferens.
The effects of okadaic acid (30 microM), a protein phosphatase inhibitor, on noradrenaline (NA) release evoked by 70 mM KCl and 100 microM ouabain were evaluated in guinea-pig vas deferens. Release of NA evoked by high KCl was inhibited by okadaic acid but this inhibition was antagonized by Bay K 8644. Furthermore, okadaic acid, like Ca(2+)-channel blockers, reduced NA release by ouabain. However, ATP-release induced by alpha,beta-methylene ATP was virtually unaffected by okadaic acid or Ca(2+)-free medium. These findings suggest that phosphatases may play an important role in Ca(2+)-channel activation and consequent NA exocytosis from adrenergic nerves.
Ogawa
S
S
Department of Pharmacology, School of Medicine, Fukuoka University, Japan.
Katsuragi
T
T
Matsuo
K
K
Furukawa
T
T
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology; D004988:Ethers, Cyclic / Q000494:pharmacology*; D005089:Exocytosis / Q000187:drug effects*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D009638:Norepinephrine / Q000378:metabolism*; D019319:Okadaic Acid; D010042:Ouabain / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors*; D011189:Potassium Chloride / Q000494:pharmacology; D013997:Time Factors; D014649:Vas Deferens / Q000187:drug effects / Q000502:physiology*
D015220:Calcium Channels; D004988:Ethers, Cyclic; D019319:Okadaic Acid; D010042:Ouabain; D011189:Potassium Chloride; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D000255:Adenosine Triphosphate; D010749:Phosphoprotein Phosphatases; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; D002118:Calcium; D009638:Norepinephrine