Serotonin enhances sympathetic vasoconstrictor responses in rat isolated perfused tail artery by activation of postjunctional serotonin-2 receptors.
The effects of serotonin and the selective serotonin-2 receptor antagonist ketanserin have been investigated on sympathetic vasoconstrictor responses in rat isolated perfused/superfused proximal tail artery segments. Serotonin (6 nmol/l) markedly enhanced responses to low frequency, short duration electrical stimulation (0.1 ms pulses at 1 Hz for 10 s). Serotonin (6 nmol/l) had a very slight (less than 10 mmHg) direct vasoconstrictor effect. Both the enhancing effect of serotonin on responses to electrical stimulation and the slight direct vasoconstrictor effect were blocked by ketanserin (3 nmol/l). Ketanserin (3 nmol/l) had no significant effect on resting tone or on responses to electrical stimulation. It is concluded that serotonin enhances sympathetic vasoconstrictor responses in rat tail artery by activation of postjunctional serotonin-2 receptors. Blockade of this effect by ketanserin is entirely consistent with its antihypertensive effect in vivo.
D000818:Animals; D004558:Electric Stimulation; D066298:In Vitro Techniques; D007650:Ketanserin; D010880:Piperidines / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011985:Receptors, Serotonin / Q000187:drug effects*; D012701:Serotonin / Q000494:pharmacology*; D013564:Sympathetic Nervous System / Q000502:physiology*; D013623:Tail / Q000098:blood supply; D014661:Vasoconstriction / Q000187:drug effects*
D010880:Piperidines; D011985:Receptors, Serotonin; D012701:Serotonin; D007650:Ketanserin