These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Species difference in the 5-hydroxytryptamine3 receptor associated with the von Bezold-Jarisch reflex.
    Author: Yamano M, Ito H, Kamato T, Miyata K.
    Journal: Arch Int Pharmacodyn Ther; 1995; 330(2):177-89. PubMed ID: 8861711.
    Abstract:
    Species differences in the 5-hydroxytryptamine (5-HT)3 receptor among anesthetized rats, mice, rabbits, ferrets, dogs and guinea-pigs were examined in the transient bradycardia induced by i.v. injection of 5-HT (the von Bezold-Jarisch reflex). We also investigated the mechanism of the 5-HT-induced bradycardia in these species. 5-Hydroxytryptamine and the selective 5-HT3 receptor agonists, 2-methyl-5-HT and m-chlorophenylbiguanide, dosedependently decreased heart rate in all species. In anesthetized rats, mice, ferrets and guinea-pigs, 2-methyl-5-HT and m-chlorophenylbiguanide behaved as full agonists against the 5-HT3 receptor, whereas their agonistic action in rabbits was partial. On the basis of ED50 values, there was no marked species difference in the potency of 5-HT3 receptor agonists. In contrast, the blocking activities of the 5-HT3 receptor antagonists, YM060, YM114 (KAE-393), granisetron and ondansetron, were markedly weaker in anesthetized guinea-pigs than in the other species. With regard to the mechanism of the 5-HT-induced bradycardia, YM060, atropine or vagotomy completely inhibited the 5-HT-induced bradycardia in anesthetized rats and mice. In guinea-pigs, in contrast, higher doses of YM060 and atropine or vagotomy inhibited this reflex by approximately 80%. Although the YM060-resistant part of the 5-HT-induced bradycardia in guinea-pigs was affected by neither 5-HT2 receptor antagonists nor 5-HT4 receptor antagonists, it was completely abolished by methysergide, a 5-HT1-like and 5-HT2 receptor antagonist. These results suggest that there is a species difference in the 5-HT3 receptor between guinea-pigs and other species in the von Bezold-Jarisch reflex system. They also suggest that the 5-HT-induced bradycardia in anesthetized rats and mice is evoked by acetylcholine released through activation of 5-HT3 receptors on the vagus nerve, while that in guinea-pigs is, at least in part, mediated through 5-HT1-like receptors in addition to 5-HT3 receptors.
    [Abstract] [Full Text] [Related] [New Search]