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. 1995 Jul;115(6):933–936. doi: 10.1111/j.1476-5381.1995.tb15900.x

Labelling with [125I]-SB 207710 of a small 5-HT4 receptor population in piglet right atrium: functional relevance.

A J Kaumann 1, J A Lynham 1, A M Brown 1
PMCID: PMC1909015  PMID: 7582523

Abstract

1. We investigated the affinity of SB 207710 for sinoatrial 5-HT4 receptors and the density of right atrial 5-HT4 receptors with [125I]-SB 207710 in right atria of new-born piglets. 2. SB 207710 (1-100 nM) antagonized the 5-HT-evoked tachycardia surmountably with a pKB of 9.8. 3. [125I]-SB 207710 (5-1500 pM) labelled a small population of saturable binding sites with a pKD of 10.1 and with 5-HT4 receptor characteristics. The density of atrial binding sites with 5-HT4 receptor characteristics was 174 and 22 times lower respectively than those of atrial beta 1- and beta 2-adrenoceptors, labelled with (-)-[125I]-cyanopindolol. 4. We suggest that the small 5-HT4 receptor population may in part explain why the maximal tachycardia caused by 5-HT is smaller than that caused by catecholamines.

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Selected References

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