Article date: July 1995
By: Alberto J. Kaumann, James A. Lynham, Anthony M. Brown, in Volume 115, Issue 6, pages 933-936
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.
SB 207710 (1–100 nM) antagonized the 5‐HT‐evoked tachycardia surmountably with a pKB of 9.8.
[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 β1 and β2‐adrenoceptors, labelled with (−)−[125I]‐cyanopindolol.
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.
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.
SB 207710 (1–100 nM) antagonized the 5‐HT‐evoked tachycardia surmountably with a pKB of 9.8.
[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 β1 and β2‐adrenoceptors, labelled with (−)−[125I]‐cyanopindolol.
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.
DOI: 10.1111/j.1476-5381.1995.tb15900.x
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