Piglet sinoatrial 5-HT receptors resemble human atrial 5-HT4-like receptors |
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Authors: | Alberto J. Kaumann |
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Affiliation: | (1) Smith Kline Beecham Pharmaceuticals, The Frythe, Welwyn, AL6 9AR Hertfordshire, UK |
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Abstract: | Summary 5-Hydroxytryptamine (5-HT), 5-carboxamidotryptamine (5-CT) and the gastrointestinal kinetic benzamides renzapride and cisapride caused tachycardia in spontaneously beating right atria of piglet in the presence of 400 nmol/l(±)-propranolol and 6 mol/l cocaine. The maximum tachycardia caused by agonists, compared to that evoked by 200 mol/l(–)-isoprenaline, was 63% for 5-HT, 50% for 5-CT, 50% for renzapride and 28% for cisapride. The rank order of potency was 5-HT > renzapride > cisapride > 5-CT. The effects of the agonists, but not those of (–)-isoprenaline, were antagonised by 3-tropanyl-1H-indole-3-carboxylic acid (ICS 205930); the pKB of ICS 205930 (vs 5-HT) was 6.9. These characteristics suggest that piglet sinoatrial 5-HT receptors are similar to so-called 5-HT4 receptors previously described in mouse colliculi neurons. Piglet sinoatrial 5-HT4-like receptors resemble the human atrial 5-HT receptors that mediate positive isotropic effects of 5-HT.Send of fprint requests to A. J. Kaumann at the above address |
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Keywords: | Piglet sinoatrial node 5-Hydroxytryptamine Benzamides 5-Carboxamidotryptamine 5-HT4-like receptors |
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