Antagonism by glibenclamide of the effect of morphine in hippocampal preparations.
We previously showed that morphine lowered the affinity of Ca2+ antagonist binding and subsequently enhanced field potentials in hippocampal preparations. In the present study, the effect of various K+ channel antagonists on these actions of morphine was studied. Higher Kd value of [3H]nitrendipine binding was obtained for membranes prepared from slices treated with morphine. Concomitant treatment of slices with morphine and tetramethylammonium (TMA) or glibenclamide attenuated the effect of morphine. Apamin and mast cell-degranulating (MCD) peptide were without effect on morphine-induced change in [3H]nitrendipine binding. In those experiments, no change in concentration of binding sites was observed. Glibenclamide reduced the morphine enhancement of field potentials. These results suggested the regulation of Ca2+ channels by morphine through K+ channel opening.
Uchida
Y
Y
Department of Pharmacology, Faculty of Dentistry, Osaka University, Japan.
Saito
K
K
Ohnishi
T
T
Maeda
S
S
Matsuya
T
T
Inoki
R
R
D000818:Animals; D005071:Evoked Potentials / Q000187:drug effects; D005905:Glyburide / Q000494:pharmacology*; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D009020:Morphine / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D009568:Nitrendipine / Q000493:pharmacokinetics; D015221:Potassium Channels / Q000187:drug effects; D017966:Pyramidal Cells / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
D015221:Potassium Channels; D009020:Morphine; D009568:Nitrendipine; D005905:Glyburide