Fenamates potentiate the alpha 1-adrenoceptor-activated nonselective cation channels in rabbit portal vein smooth muscle.
The agonistic action of fenamates on the alpha 1-adrenoceptor-activated cationic current (Icat) in rabbit portal vein smooth muscle was investigated with the whole-cell patch clamp technique. At -50 mV, the fenamates (100-500 microM) increased Icat dose-dependently, up to several fold. This increase was not accompanied by changes in the reversal potential and strongly inhibited by 500 microM Cd2+ or 10 mM procaine. The enhancing effect of fenamates was also observed on the cationic current activated by intracellularly applied GTP gamma S. These results suggest that fenamates may be useful as a new class of activator for receptor-operated cation channels in smooth muscle.
Yamada
K
K
Department of Pharmacology, Kyushu University, Fukuoka, Japan.
Waniishi
Y
Y
Inoue
R
R
Ito
Y
Y
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D002412:Cations; D004357:Drug Synergism; D005439:Flufenamic Acid / Q000494:pharmacology; D007473:Ion Channels / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D008528:Mefenamic Acid / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010656:Phenylephrine / Q000494:pharmacology; D011169:Portal Vein / Q000187:drug effects* / Q000378:metabolism; D011817:Rabbits; D018340:Receptors, Adrenergic, alpha-1 / Q000187:drug effects / Q000378:metabolism*; D062367:ortho-Aminobenzoates / Q000494:pharmacology*
D000316:Adrenergic alpha-Agonists; D002412:Cations; D007473:Ion Channels; D018340:Receptors, Adrenergic, alpha-1; D062367:ortho-Aminobenzoates; D010656:Phenylephrine; D008528:Mefenamic Acid; D005439:Flufenamic Acid; C001209:fenamic acid