Serotonin-induced contraction in canine coronary artery and saphenous vein: Role of a 5-HT 1D-like receptor

Abstract

The identity of the serotonin (5-HT) receptor(s) that mediate(s) contraction in canine coronary artery and saphenous vein remains controversial. Ring segments of endothelium-denuded coronary artery and helical strips of saphenous vein were suspended in organ chambers for measurement of isometric force. 5-HT, αMe-5-HT and sumatriptan contracted both coronary artery and saphenous vein and the non-selective 5-HT receptor antagonist 1-naphthylpiperazine (100nM) blocked 5-HT-and sumatriptan-induced contraction in both tissues. The agonist rank order potency for contraction (5-HT>sumatriptan>αMe5-HT>5-MeOT>5-MeT) was similar in both tissues and was consistent with that for a 5-HT 1D receptor. Oligonucleotide primers specific for the 5-HT 1D receptor sequence were designed for use in a polymerase chain reaction (PCR). cDNA derived from total RNA or mRNA from canine tissues was used in the PCR. PCR resulted in the amplification of a 632 base pair sequence in both canine coronary artery and saphenous vein; consistent with that expected for the 5-HT 1D receptor. Southern blot analysis, with an oligonucleotide probe internal to the sequence amplified by the PCR primers, confirmed that the sequence amplified by PCR was the 5-HT 1D receptor. Thus, the 5-HT 1D receptor is expressed in canine coronary artery and saphenous vein and taken together with the pharmacological data, supports the possibility that a 5-HT 1D-like receptor mediates contraction in these two tissues.