Inhibitory effect of ethanol on the 5-hydroxytryptamine-induced Bezold-Jarisch reflex--involvement of peripheral 5-HT3 receptors.
The influence of ethanol (0.5, 1.0 and 2.0 g/kg i.p.) on the Bezold-Jarisch reflex in urethane-anaesthetized rats was studied. 5-Hydroxytryptamine (serotonin; 5-HT; 1, 3, 10 and 30 micrograms/kg i.v.) and capsaicin (1, 3 and 10 micrograms/kg i.v.) reflexly decreased heart rate in a dose-dependent manner. The 5-HT3 receptor antagonist ondansetron 10 micrograms/kg i.v. abolished the 5-HT- but not the capsaicin-stimulated bradycardia, indicating that 5-HT and capsaicin acted via different trigger mechanisms (5-HT3 receptor-dependent and -independent, respectively). Ethanol at 1.0 and 2.0 g/kg i.p. inhibited in a dose-dependent manner (by 20-45%) the 5-HT- but not the capsaicin-stimulated decrease in heart rate. Our results demonstrate that the inhibitory effect of ethanol on the 5-HT3 receptor-mediated Bezold-Jarisch reflex may be related to the direct effect of ethanol on 5-HT3 receptors on sensory vagal nerves in the heart.
Malinowska
B
B
Zaklad Farmakodynamiki Akademia Medyczna, Bialystok, Poland.
Göthert
M
M
Godlewski
G
G
Wróbel
B
B
Bönisch
H
H
Buczko
W
W
D000818:Animals; D002211:Capsaicin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects*; D008297:Male; D009412:Nerve Fibers / Q000187:drug effects; D009475:Neurons, Afferent / Q000187:drug effects; D017294:Ondansetron / Q000494:pharmacology; D010525:Peripheral Nerves / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D011985:Receptors, Serotonin / Q000187:drug effects*; D012018:Reflex / Q000187:drug effects*; D012702:Serotonin Antagonists / Q000494:pharmacology*; D014630:Vagus Nerve / Q000187:drug effects
D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D000431:Ethanol; D017294:Ondansetron; D002211:Capsaicin