Effect of 5-hydroxytryptamine on external carotid nerve activity and its blockade by GR38032F in anesthetized rats.
Excitatory response to 5-hydroxytryptamine was recorded from the external carotid nerve, a branch of the superior cervical ganglia, in anesthetized rats using an electrophysiological technique. Bolus intravenous injection of 5-HT (1.5625-50 micrograms/kg) evoked a rapid and dose-dependent excitation of external carotid nerve activity. This response was blocked by a selective 5-HT3-receptor antagonist, GR38032F (10 micrograms/kg). A 5-HT3 receptor agonist, 2-methyl-5-HT (3.125-50 micrograms/kg), also produced a rapid and dose-dependent excitation of external carotid nerve activity. GR38032F (10 micrograms/kg) caused a significant rightward shift in the 2-methyl-5-HT dose-response curve. These results suggest that the 5-HT-induced excitatory response of ECNA might be mediated via a 5-HT3 receptor.
Yoshioka
M
M
First Department of Pharmacology, Hokkaido University School of Medicine, Sapporo, Japan.
Ikeda
T
T
Abe
M
M
Togashi
H
H
Saito
H
H
D000704:Analysis of Variance; D000818:Animals; D004305:Dose-Response Relationship, Drug; D007093:Imidazoles / Q000494:pharmacology*; D008297:Male; D017294:Ondansetron; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000031:analogs & derivatives / Q000494:pharmacology*; D012702:Serotonin Antagonists; D013564:Sympathetic Nervous System / Q000187:drug effects* / Q000502:physiology
D007093:Imidazoles; D012702:Serotonin Antagonists; D012701:Serotonin; D017294:Ondansetron; C045918:2-methyl-5-HT