5-HT4 receptors, present in piglet atria and sensitive to SDZ 205-557, are absent in papillary muscle.
Putative 5-HT4 receptors were investigated in isolated piglet left atria and papillary muscles. In atrial tissues, 5-hydroxytryptamine (5-HT) was a potent positive inotropic agent with a pD2 of 6.7. Its effects were antagonised in a selective and competitive manner by the 5-HT4 receptor antagonist, SDZ 205-557, with a pA2 of 7.3. In contrast to atrial tissues, piglet papillary muscles were virtually unresponsive to 5-HT 10(-8)-10(-3) M, suggesting that functional cardiac 5-HT4 receptors are not present in ventricular tissue.
Lorrain
J
J
Synthélabo Recherche (L.E.R.S.), Department of Biology, Bagneux, France.
Grosset
A
A
O'Connor
S E
SE
D010129:4-Aminobenzoic Acid / Q000494:pharmacology; D000818:Animals; D002316:Cardiotonic Agents / Q000494:pharmacology; D005260:Female; D006325:Heart Atria / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D010210:Papillary Muscles / Q000187:drug effects*; D011985:Receptors, Serotonin / Q000145:classification / Q000502:physiology*; D012701:Serotonin / Q000494:pharmacology; D012702:Serotonin Antagonists; D013552:Swine; D062366:para-Aminobenzoates
D002316:Cardiotonic Agents; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D062366:para-Aminobenzoates; C072790:2-methoxy-4-amino-5-chlorobenzoic acid 2-(diethylamino)ethyl ester; D012701:Serotonin; D010129:4-Aminobenzoic Acid