Blocking effect of serotonin on beta-adrenoceptor activity in follicle-enclosed Xenopus oocytes.
The effects of serotonin (5-HT) on a beta-adrenergic response were studied, using the voltage clamp technique, in Xenopus laevis oocytes surrounded by their follicular cells. noradrenaline induced marked hyperpolarization, with a specific increase in the permeability of the membrane toward K+. Application of 10 microM 5-HT had little effect on the resting membrane, but significantly depressed the response to 0.1 microM noradrenaline. The dose-response curve for noradrenaline showed a parallel shift to the right in the presence of 5-HT, suggesting that 5-HT competes with noradrenaline for common binding sites at the beta-adrenoceptor.
Fujita
R
R
Department of Physiology, School of Medicine, Iwate Medical University, Morioka, Japan.
Tamazawa
Y
Y
Barnard
E A
EA
Matsumoto
M
M
D000818:Animals; D001665:Binding Sites; D002463:Cell Membrane Permeability / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D005260:Female; D009638:Norepinephrine / Q000378:metabolism / Q000494:pharmacology; D009865:Oocytes / Q000187:drug effects* / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D011943:Receptors, Adrenergic, beta / Q000187:drug effects* / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism / Q000494:pharmacology*; D014982:Xenopus laevis
D011943:Receptors, Adrenergic, beta; D012701:Serotonin; D011188:Potassium; D009638:Norepinephrine