dinoprost and 5-carboxamidotryptamine

Using a series of triptans we characterized in vitro the 5-hydroxytryptamine (5-HT) receptor that mediates the contraction in guinea-pig iliac arteries moderately precontracted by prostaglandin F2alpha (PGF2alpha). Additionally, we investigated by reverse-transcriptase polymerase chain reaction (RT-PCR) which triptan-sensitive receptor is present in this tissue. Frovatriptan, zolmitriptan, rizatriptan, naratriptan, sumatriptan, and almotriptan contracted guinea-pig iliac arteries with pD2 values of 7.52+/-0.04, 6.72+/-0.03, 6.38+/-0.06, 6.22+/-0.05, 5.86+/-0.05 and 5.26+/-0.04 respectively. For comparison, the pD2 values for 5-HT and 5-carboxamidotryptamine (5-CT) were 7.52+/-0.02 and 7.55+/-0.03 respectively. In contrast to all other triptans tested, the concentration-response curve for eletriptan was biphasic (first phase: 0.01-3 microM, pD2 approximately 6.6; second phase: > or = 10 microM). Contractions to 5-HT, 5-CT, frovatriptan, zolmitriptan, rizatriptan, naratriptan, sumatriptan, almotriptan, and eletriptan (first phase) were antagonized by the 5-HT1B/1D receptor antagonist GR127935 (10 nM) and the 5-HT1B receptor antagonist SB216641 (10 nM). RT-PCR studies in guinea-pig iliac arteries showed a strong signal for the 5-HT1B receptor while expression of 5-HT1D and 5-HT1F receptors was not detected in any sample. The present results demonstrate that triptan-induced contraction in guinea-pig iliac arteries is mediated by the 5-HT1B receptor. The guinea-pig iliac artery may be used as a convenient in vitro model to study the (cardio)vascular side-effect potential of anti-migraine drugs of the triptan family.

Topics: Animals; Benzamides; Brain; Carbazoles; Dinoprost; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Endothelium, Vascular; Female; Forecasting; Guinea Pigs; Iliac Artery; Indoles; Ketanserin; Male; Muscle Contraction; Muscle, Smooth; Oxadiazoles; Oxazolidinones; Piperazines; Piperidines; Pyrrolidines; Receptor, Serotonin, 5-HT1B; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Serotonin; Serotonin 5-HT1 Receptor Antagonists; Sumatriptan; Triazoles; Tryptamines

This study aimed to determine, quantify and explain regional differences in the relaxant response to the selective 5-HT(1) and 5-HT(7) receptor agonist 5-carboxamidotryptamine (5-CT) throughout the canine stomach. Longitudinal muscle strips from eight gastric corpus regions and six antrum regions were mounted for isotonic measurement. The 5-CT-induced relaxation was examined on a prostaglandin F(2alpha)-induced submaximal response, expressed as percentage of this response and fitted to the operational model of agonism (OMOA). 5-HT(7) receptor messenger RNA (mRNA) expression was compared by means of quantitative PCR. 5-CT inhibited PGF(2alpha)-induced tonic contraction (corpus) and increase of phasic contraction amplitude (antrum). The consistent antagonism produced by the selective 5-HT(7) receptor antagonist SB-269970 (10 nm, pA(2) estimates 8.2-8.9) confirmed that in every region, the inhibition by 5-CT was 5-HT(7) receptor mediated. However, variation in the maximum effect (61-108%) and pEC(50) (6.4-8.6) was observed throughout the different regions. The OMOA explained these differences as differences in the efficacy parameter tau (ratio of receptor density and coupling efficiency; log tau estimates ranging from 0.1 to 2.1). The log tau gradient decreases going from the lesser to the greater curvature. A proportional difference (68%) in the relative expression of 5-HT(7) receptor mRNA between the lesser and the greater curvature indicates that differences in receptor density contribute to the observed functional differences. This study illustrates that 5-HT(7) receptors are present throughout the ventral wall of the canine stomach, but the efficacy (expressed as log tau) is clearly greater close to the lesser curvature. Differences in 5-HT(7) receptor expression at least partially explain the functional differences.

Topics: Alternative Splicing; Animals; Dinoprost; Dogs; Dose-Response Relationship, Drug; Female; Gastric Mucosa; Gene Expression; In Vitro Techniques; Male; Molecular Sequence Data; Muscle Contraction; Muscle Relaxation; Nitroprusside; Phenols; Protein Isoforms; Receptors, Serotonin; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Serotonin; Serotonin Antagonists; Serotonin Receptor Agonists; Stomach; Sulfonamides; Tetrodotoxin

Vascular serotonin 5-HT1 receptors have quiescent constrictor activity that is activated by other vasoactive agents such as histamine. Previously, we observed that the 5-HT1-selective agonist 5-carboxamidotryptamine (5-CT) potentiated histamine-stimulated arachidonic acid (AA) mobilization and prostaglandin production in human aortic endothelial cells (HAEC). In the present study, 5-CT was found to potentiate histamine-stimulated calcium mobilization but had no effect on intracellular calcium when added alone. Treatment of HAEC with human low-density lipoprotein (LDL) for 20 hours inhibited the histamine- plus 5-CT-stimulated production of prostaglandin F2alpha (PGF2alpha) and the prostacyclin metabolite 6-keto-PGF1alpha. However, the effects of histamine and histamine potentiation by 5-CT on intracellular Ca mobilization and AA release were resistant to LDL treatment. Conversely, the subsequent receptor-independent conversion of AA to prostaglandins was inhibited by LDL. These results demonstrate that histamine and serotonin receptor activity, measured as the stimulation of Ca and AA mobilization, is resistant to LDL exposure under mild oxidizing conditions, whereas the receptor-independent synthesis of prostaglandins is inhibited by LDL. The results also suggest that the LDL-stimulated mobilization of cellular AA is responsible for the LDL-mediated inhibition of prostaglandin synthesis. These findings suggest a mechanism by which LDL and/or atherosclerosis could promote the vascular liberation of AA that is not converted to endothelium-derived prostaglandins and is therefore available as substrate for the production of other eicosanoids.

Topics: 6-Ketoprostaglandin F1 alpha; Aorta; Arachidonic Acid; Calcium; Cells, Cultured; Culture Media; Cyclic AMP; Dinoprost; Dose-Response Relationship, Drug; Drug Synergism; Endothelial Cells; Histamine; Humans; Lipoproteins, LDL; Receptors, Serotonin, 5-HT1; Serotonin; Time Factors

The ability of serotonin 5-HT1 receptors to increase vascular tone was previously found to be activated by vasoconstrictiors such as histamine. In this study, treatment of cultured human aortic endothelial cells (HAEC) with the 5-HT1-selective agonist 5-carboxamidotryptamine (5-CT) alone had no effect on the levels of prostaglandin F2alpha (PGF2alpha) or 6-keto-prostaglandin F1alpha (6-keto PGF1alpha). However, 5-CT potentiated the histamine and thrombin stimulated increases in prostaglandins released by HAEC. In the presence of histamine, increasing doses of 5-CT caused a steep rise in PGF2alpha levels resulting in an increase in the ratio of PGF2alpha over 6-keto PGF1alpha. The ability of 5-CT to potentiate prostaglandin production was correlated with its ability to potentiate the histamine and thrombin mediated mobilization of arachidonic acid. These results demonstrate that the ability of 5-HT1 receptors to stimulate prostaglandin production in endothelial cells is activated by histamine and thrombin.

Topics: 6-Ketoprostaglandin F1 alpha; Arachidonic Acid; Dinoprost; Dose-Response Relationship, Drug; Drug Synergism; Endothelium, Vascular; Histamine; Humans; Prostaglandins; Receptors, Serotonin; Receptors, Serotonin, 5-HT1; Serotonin; Serotonin Receptor Agonists; Thrombin

The antimigraine drug, sumatriptan, contracts the human coronary artery both in vivo and in vitro. Because sumatriptan has been associated with cardiac side effects, it is important to characterise the receptor involved in sumatriptan-induced coronary artery contraction. Using the agonists sumatriptan and 5-carboxamidotryptamine and the selective 5-HT1B/1D receptor antagonist GR55562, we have investigated the involvement of 5-HT1B/1D receptors in the contraction of the human isolated coronary artery. Contractions to sumatriptan (pEC50: 6.1+/-0.2, maximal effect: 21+/-4% of 100 mM K+-induced contraction) were competitively antagonised by GR55562. The pA2 of GR55562 (7.40+/-0.16) was in accord with its reported affinity at the human 5-HT1B receptor. Since the contractions to 5-carboxamidotryptamine did not reach a maximum with the highest concentration used (10 microM), pEC50 values could not be calculated for Schild analysis. However, using the pEC10%/K+ values (negative logarithm of the concentration needed to induce 10% of the contraction to 100 mM K+), GR55562 proved a less potent antagonist against 5-carboxamidotryptamine than against sumatriptan. These results show that sumatriptan contracts the human isolated coronary artery via 5-HT1B/1D receptors, most probably the 5-HT1B subtype. 5-Carboxamidotryptamine may contract the human isolated coronary artery, at least partly, via a novel yet to be characterised, receptor.

Topics: Benzamides; Coronary Vessels; Dinoprost; Dose-Response Relationship, Drug; Drug Interactions; Humans; In Vitro Techniques; Muscle Contraction; Muscle, Smooth, Vascular; Potassium; Pyridines; Receptor, Serotonin, 5-HT1B; Receptors, Serotonin; Serotonin; Serotonin Antagonists; Substance P; Sumatriptan; Vasoconstrictor Agents

1. We investigated in the present study whether 5-HT is able to exert direct relaxant responses in canine basilar and middle cerebral arteries via the 5-HT7 receptor. 2. In arterial rings deprived of endothelium and pre-contracted with prostaglandin F2 alpha (2 microM), 5-HT, 5-carboxamidotryptamine (5-CT), 5-methoxytryptamine, sumatriptan or alpha-methyl-5-HT produced further increase in tone and/or slight relaxation. Blockade of 5-HT1B 1D and 5-HT2A receptors with GR127935 (1 microM) and ketanserin (0.1 microM), respectively, antagonized the vasoconstrictor component of the response and unmasked a concentration-dependent relaxation to 5-HT, 5-CT and 5-methoxytryptamine; sumatriptan and alpha-methyl-5-HT remained inactive as relaxant agonists. The rank order of agonist potency in both arteries was 5-CT > 5-HT > 5-methoxytryptamine >> sumatriptan > or = alpha-methyl-5-HT. 3. In dog basilar artery, pre-incubated with GR127935 (1 microM) and ketanserin (0.1 microM) and precontracted with prostaglandin F2 alpha (2 microM), the 5-HT7 ligands, clozapine (1 microM), mesulergine (0.3 microM), methiothepin (3 nM), risperidone (3 nM), spiperone (1 microM) and LY215840 (10-100 nM), produced significant rightward shifts of the concentration-response curves for 5-HT and 5-CT. Only methiothepin and risperidone reduced significantly the maximum relaxant response (Emax), whilst the other drugs behaved as competitive antagonists with affinity values (pKB) that significantly correlated with their binding affinity (pKi) at recombinant 5-HT7 receptors. 4. These data disclosing the involvement of the 5-HT7 receptor in cerebrovascular relaxation may be strongly relevant in the light of: (1) the involvement of 5-HT in migraine; (2) the putative linkage between cephalovascular vasodilatation and migraine headache; and (3) the relatively high 5-HT7 receptor affinity of migraine prophylactic 5-HT antagonists.

Topics: Animals; Basilar Artery; Cerebral Arteries; Dinoprost; Dogs; Endothelium, Vascular; Female; In Vitro Techniques; Male; Muscle Relaxation; Muscle, Smooth, Vascular; Receptors, Serotonin; Serotonin; Serotonin Receptor Agonists; Spiperone; Sumatriptan

Topics: Animals; Basilar Artery; Dinoprost; Dogs; Dose-Response Relationship, Drug; In Vitro Techniques; Ketanserin; Lysergic Acid; Muscle Relaxation; Muscle, Smooth, Vascular; Oxadiazoles; Piperazines; Receptors, Serotonin; Serotonin; Serotonin Antagonists; Serotonin Receptor Agonists

The 5-hydroxytryptamine (5-HT) receptor mediating endothelium-dependent relaxation of pig coronary arteries was characterized using a variety of 5-HT receptor agonists and antagonists. Unrubbed (with endothelium preserved) rings precontracted by prostaglandin F2 alpha in the presence of ketanserin relaxed in an endothelium-dependent manner to 5-HT, 5-carboxamidotryptamine and 5-methoxytryptamine with about equal potency and efficacy. By comparison, bufotenine, 3-(dimethylamino)ethyl-N-methyl-1H-indole-5-methane sulfonamide, (-)-alpha-methyl-5-HT,N,N-dipropyl-5-carboxamidotryptamine and 5-methoxy-3-(1,2,3,6-tetrahydro-4-pyridinyl)-1H indole were half-efficient and other drugs [in particular the 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin] were inactive as agonists up to 0.1 mM. The effect of 5-carboxamidotryptamine was antagonized in an apparently competitive manner by 15 drugs. Among the most potent antagonists (mean pKB value) were the nonselective 5-HT receptor antagonists, methiothepin (7.30) and metergoline (6.86), the 5-HT1A/5-HT1D receptor ligand, 1-[2-(4-amino-phenyl)ethyl]-4-(3-trifluoromethylphenyl)-piperazine (7.02), the 5-HT1A/5-HT1B/5-HT1D receptor ligand, 7-trifluoromethyl-4-(4-methyl-1-piperazinyl)-pyrrolo[1,2,-a]quinoxaline 1 (6.73) and yohimbine (6.37). Selective ligands for 5-HT1A receptors were either inactive [8-hydroxy-2-(di-n-propylamino)tetralin hydrobromide] or poorly active (spiperone, 4.44). Beta-adrenoceptor antagonists with affinity for 5-HT1A and 5-HT1B receptors weakly antagonized the effect of 5-carboxamidotryptamine (pKB values less than or equal to 5.32), as did the 5-HT1c/5-HT2 receptor antagonist, mesulergine (5.30) and the yohimbine isomer, corynanthine (4.85). Methysergide was clearly a noncompetitive antagonist.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: 8-Hydroxy-2-(di-n-propylamino)tetralin; Adenylyl Cyclases; Animals; Dinoprost; Dose-Response Relationship, Drug; Endothelium, Vascular; In Vitro Techniques; Radioligand Assay; Receptors, Serotonin; Serotonin; Serotonin Antagonists; Swine; Tetrahydronaphthalenes; Vasodilation

The 5-hydroxytryptamine (5-HT) receptor mediating contraction of rabbit isolated endothelium denuded basilar artery has been investigated. 5-HT and a variety of 5-HT receptor agonists contracted rabbit isolated basilar artery with a rank order of agonist potency: 5-carboxamidotryptamine (5-CT) greater than 5-HT greater than GR43175. None of these agonists relaxed rabbit isolated basilar artery when tone was elevated with prostaglandin F2alpha. The contractile response to both 5-HT and GR43175 was resistant to antagonism by GR38032, phentolamine, (+/-)-cyanopindolol and yohimbine. Ketanserin (100 nM) and mesulergine (100 nM) produced small significant rightward shifts of C-E curves to 5-HT with respective concentration-ratio shifts of 5.7 (1.5-21.0 95% confidence interval and 2.89 (1.1-7.6 95% confidence interval). GR43175-induced contraction was resistant to antagonism by ketanserin however the maximum response to GR43175 was significantly reduced in the presence of mesulergine, with no change in EC50. Methiothepin was a potent antagonist of the contractile actions of both 5-HT and GR43175, with respective pA2 values against each agonist of 10.3 and 9.9. The slope of the Schild regression for methiothepin against 5-HT-induced contraction was significantly less than unity. Methiothepin (100 nM) had no effect on the contractile response to the thromboxane A2 mimetic U-46619. It is concluded that 5-HT and GR43175 contract rabbit isolated basilar artery by activating a 5-HT1-like receptor. In addition 5-HT may activate a population of 5-HT2 receptors producing a further contraction of rabbit isolated basilar artery.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Basilar Artery; Dinoprost; Endothelium, Vascular; In Vitro Techniques; Indoles; Male; Muscle Contraction; Muscle Tonus; Muscle, Smooth, Vascular; Rabbits; Receptors, Serotonin; Serotonin; Serotonin Antagonists; Sulfonamides; Sumatriptan

5-Carboxamidotryptamine (5-CT) caused concentration dependent relaxation of isolated rings from the porcine vena cava contracted with either prostaglandin F2 alpha, histamine or alpha-methyl 5-hydroxytryptamine. Relaxation was not inhibited by propranolol (l microM), atropine (1 microM), indomethacin (3 microM), mepyramine (1 microM), cimetidine (1 microM), or cocaine (10 microM). Methysergide, but not cyproheptadine, was a competitive antagonist of the relaxant effect of 5-CT with a pA2 value of 7.88. 5-Carboxamidotryptamine also increased the intracellular levels of cyclic AMP, an effect which was antagonised by methysergide (apparent pA2: 7.95) but not cyproheptadine. The alpha-methyl analogue of 5-hydroxytryptamine did not cause relaxation or elevate cyclic AMP. These results suggest that 5-CT causes relaxation and elevation of cyclic AMP by interaction with a specific 5-hydroxytryptamine receptor which is '5-HT1-like'.

Topics: 1-Methyl-3-isobutylxanthine; Animals; Animals, Newborn; Atropine; Cimetidine; Cocaine; Cyclic AMP; Dinoprost; Histamine; In Vitro Techniques; Indomethacin; Muscle Contraction; Muscle Relaxation; Muscle, Smooth, Vascular; Propranolol; Prostaglandins F; Pyrilamine; Serotonin; Serotonin Antagonists; Swine; Vena Cava, Inferior