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

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.

• Authors: A J Kaumann, J A Lynham, A M Brown
• Journal: British journal of pharmacology (Br J Pharmacol) Vol. 115 Issue 6 Pg. 933-6 (Jul 1995) ISSN: 0007-1188 [Print] England
• PMID: 7582523 (Publication Type: Journal Article)

Chemical References

• Dioxanes
• Piperidines
• Receptors, Serotonin
• SB 207710
• Serotonin Antagonists
• Serotonin

Topics

• Animals
• Animals, Newborn
• Atrial Function, Right (drug effects)
• Binding, Competitive
• Dioxanes (pharmacology)
• Dose-Response Relationship, Drug
• Female
• Male
• Piperidines (pharmacology)
• Receptors, Serotonin (classification, drug effects, physiology)
• Serotonin (pharmacology)
• Serotonin Antagonists (pharmacology)
• Swine
• Tachycardia (chemically induced)