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PubMed1997

Characterization of putative 5-HT7 receptors mediating tachycardia in the cat.

1. It has been suggested that the tachycardic response to 5-hydroxytryptamine (5-HT) in the spinal-transected cat is mediated by '5-HT1-like' receptors since this effect, being mimicked by 5-carboxamidotryptamine (5-CT), is not modified by ketanserin or MDL 72222, but it is blocked by methiothepin, methysergide or mesulergine. The present study was set out to reanalyse this suggestion in terms of the IUPHAR 5-HT receptor classification schemes proposed in 1994 and 1996. 2. Intravenous (i.v.) bolus injections of the tryptamine derivatives, 5-CT (0.01, 0.03, 0.1, 0.3, 1, 3, 10 and 30 microg kg(-1)), 5-HT (3, 10 and 30 microg kg(-1)) and 5-methoxytryptamine (3, 10 and 30 microg kg(-1)) as well as the atypical antipsychotic drug, clozapine (1000 and 3000 microg kg(-1)) resulted in dose-dependent increases in heart rate, with a rank order of agonist potency of 5-CT >> 5-HT > 5-methoxytryptamine >> clozapine. 3. The tachycardic effects of 5-HT and 5-methoxytryptamine were dose-dependently antagonized by i.v. administration of lisuride (30 and 100 microg kg(-1)), ergotamine (100 and 300 microg kg(-1)) or mesulergine (100, 300 and 1000 microg kg(-1)); the highest doses of these antagonists used also blocked the tachycardic effects of 5-CT. Clozapine (1000 and 3000 microg kg(-1)) did not affect the 5-HT-induced tachycardia, but attenuated, with its highest dose, the responses to 5-methoxytryptamine and 5-CT. However, these doses of clozapine as well as the high doses of ergotamine (300 microg kg(-1)) and mesulergine (300 and 1000 microg kg(-1)) also attenuated the tachycardic effects of isoprenaline. In contrast, 5-HT-, 5-methoxytryptamine- and 5-CT-induced tachycardia were not significantly modified after i.v. administration of physiological saline (0.1 and 0.3 ml kg(-1)), the 5-HT(1B/1D) receptor antagonist, GR127935 (500 microg kg(-1)) or the 5-HT(3/4) receptor antagonist, tropisetron (3000 microg kg(-1)). 4. Intravenous injections of the 5-HT1 receptor agonists, sumatriptan (30, 100 and 300 microg kg(-1)) and indorenate (300 and 1000 microg kg(-1)) or the 5-HT4 receptor (partial) agonist cisapride (300 and 1000 microg kg(-1)) were devoid of effects on feline heart rate per se and failed to modify significantly 5-HT-induced tachycardic responses. 5. Based upon the above rank order of agonist potency, the failure of sumatriptan, indorenate or cisapride to produce cardioacceleration and the blockade by a series of drugs showing high affinity for the cloned 5-ht7 receptor, the present results indicate that the 5-HT receptor mediating tachycardia in the cat is operationally similar to other putative 5-HT7 receptors mediating vascular and non-vascular responses (e.g. relaxation of the rabbit femoral vein, canine external carotid and coronary arteries, rat systemic vasculature and guinea-pig ileum). Since these responses represent functional correlates of the 5-ht7 gene product, the 5-HT7 receptor appellation is reinforced. Therefore, the present experimental model, which is not complicated by the presence of other 5-HT receptors, can be utilized to characterize and develop new drugs with potential agonist and antagonist properties at functional 5-HT7 receptors.

5-Methoxytryptamine↗
PubMed1997

NANC transmitters in the female pig urethra--localization and modulation of release via alpha 2-adrenoceptors and potassium channels.

1. To investigate further the release, localization and identity of a non-nitrergic mediator of smooth muscle relaxation in the female pig urethra, we studied the effects of drugs acting at alpha 2-adrenoceptors or K+ channels, the effects of capsaicin and chemical sympathectomy, and the actions of several transmitter candidates. 2. Electrical field stimulation (EFS; frequencies above 12 Hz) of spontaneously contracted smooth muscle strips from the female pig urethra evoked long-lasting, frequency-dependent relaxations in the presence of prazosin, scopolamine, and NG-nitro-L-arginine. Treatment with the selective alpha 2-adrenoceptor agonist UK-14 304 markedly reduced the relaxations evoked by EFS at all frequencies tested (16-30 Hz). The inhibitory effect of UK-14 304 was completely antagonized by the alpha 2-adrenoceptor antagonist rauwolscine. The muscarinic M1 receptor antagonist, pirenzepine, or exogenously administered carbachol, did not have any effects on the electrically evoked relaxations. 3. Inhibition of high conductance Ca2+ activated K+ channels by iberiotoxin or charybdotoxin significantly enhanced the relaxations evoked by EFS at all frequencies. However, inhibition of voltage-sensitive K+ channels with 4-aminopyridine or dendrotoxin-1, treatment with the ATP-sensitive K+ channel blocker, glibenclamide, or treatment with the high and low conductance Ca2+ activated K+ channel blockers, tetraethylammonium chloride and apamin, had no effect on the relaxations evoked by EFS. 4. Electrically evoked relaxations were not affected by adrenergic denervation with 6-hydroxydopamine (6-OHDA) at any frequency. However, treatment with 6-OHDA abolished prazosin-sensitive electrically induced contractions, and a long-lasting relaxation was revealed. Treatment with capsaicin, believed to damage selectively a subpopulation of primary afferent fibres, did not affect basal tone or relaxations evoked by EFS. 5. Exogenously applied vasoactive intestinal polypeptide (VIP), pituitary adenylate cyclase-activating peptide (PACAP)-27, PACAP-38, adenosine, ATP and 5-hydroxy-tryptamine caused relaxations of the urethral preparations, whereas prostaglandin E2 and calcitonin gene-related peptide had no effects. VIP 10-28, alpha, beta-methylene-ATP, reactive blue-2, suramin or indomethacin did not reduce the electrically-evoked relaxations at any frequency. However, the relaxations were slightly reduced by trypsin or alpha-chymotrypsin. 6. The present results suggest that the release of the unknown mediator in the female pig urethra can be modulated via alpha 2-adrenoceptors and high conductance Ca2+ activated K+ channels. Furthermore, the mediator does not appear to be localized to or released from adrenergic or capsaicin-sensitive sensory nerve-endings. The identity of the transmitter remains to be established.

Animals↗
PubMed1997

Cloning, expression and pharmacology of a truncated splice variant of the human 5-HT7 receptor (h5-HT7b).

1. The rat 5-hydroxytryptamine (5-HT)7 receptor displays two splice variations, a long form, and a truncated splice isoform, arising from the introduction of a stop codon near the carboxy-terminus. The human-5HT7 receptor gene contains at least two introns and encodes a 445 amino acid 5-HT receptor. 2. A truncated splice variation in the human 5-HT7 receptor was isolated from a human placental cDNA library. In accordance with current NC-IUPHAR nomenclature guidelines, it is suggested that this receptor be donated as the h5-HT7b receptor and the long form of the receptor as h5-HT7a. 3. The h5-HT7b receptor was stably expressed in HEK 293 cells and ligand affinities were determined by displacement of [3H]-5-carboxyamidotryptamine (5-CT; Kd = 0.28 +/- 0.6 nM, Bmax = 7.3 +/- 17 pmol mg-1 protein). The rank order of affinities (pKi) for a series of ligands was: 5-carboxamidotryptamine (5-CT, 9.65) > 5-hydroxytryptamine (5-HT, 9.41) > methiothepin (8.87) > mesulergine (7.87) > 8-hydroxy-2 (di-n-propylamino)tetralin (8-OH-DPAT, 6.85) > ketanserin (6.44). 4. The h5-HT7b receptor coupled positively to adenylyl cyclase in HEK 293 cells. This response was elicited by a number of agonists with the following order of potency (pEC50): 5-CT (8.7 +/- 0.11) > 5-MeOT (5-methoxytryptamine; 8.1 +/- 0.20) > 5-HT (7.5 +/- 0.13) tryptamine (5.6 +/- 0.36) > 8-OH-DPAT (5.3 +/- 0.28) > 5-methoxytryptamine (5.0 +/- 0.06). This rank order was comparable to that observed in the radioligand binding studies. 5. In a similar fashion to that described for the 5-HT7a receptor, PCR studies suggested that the 5-HT7b receptor mRNA is found in great abundance throughout the brain, in the small intestine and aorta. 6. It is concluded that the h5-HT7 receptor, like the rat receptor, exists as splice variants exhibiting similar pharmacology, signal transduction and distribution. It is thus likely that there exists a complex physiological role for alternate splicing products of the 5-HT7 receptor gene.

Alternative Splicing↗
PubMed1999

Functional characterization of agonists at recombinant human 5-HT2A, 5-HT2B and 5-HT2C receptors in CHO-K1 cells.

1. The goal of this study was to characterize the agonist pharmacology of human 5-HT2A, 5-HT2B and 5-HT2C (VSV) receptors expressed in CHO-K1 (Chinese hamster ovary) cells. 2. We used a fluorometric imaging plate reader (FLIPR) which allows rapid detection of rises in intracellular calcium levels upon the addition of agonists. 3. Stimulation of all three receptors by 5-HT caused a robust concentration dependent increase in intracellular calcium levels. No such effect was observed from non-transfected control CHO-K1 cells. 4. The rank order of potency of agonists at the different receptor subtypes varied. Tryptamines, BW-723C86, d-norfenfluramine, Ro 60-0175 and LSD exhibited the following rank order of potency; 5-HT2B>5-HT2C>5-HT2A. Piperazines such as m-Chlorophenylpiperazine (mCPP), ORG-12962, MK-212 and also ORG-37684 exhibited a rank order of potency of 5-HT2C>5-HT2B>5-HT2A. The phenylisopropylamines DOI and DOB had a rank order of 5-HT2A>5-HT2B>5-HT2C. 5. Many agonists tested had partial agonist actions when compared to 5-HT, and a wide range of relative efficacies were exhibited, which was cell line dependent. For example, mCPP had a relative efficacy of 65% at 5-HT2C receptors but <25% at either 5-HT2A or 5-HT2B receptors. 6. Interpretation of literature values of functional assays using different cell lines, different receptor expression levels and different receptor isoforms, is complex. Species differences and the previous use of antagonist radioligands to characterize agonist potency in binding assays emphasizes the importance of studying agonists in the same experiment using the same assay conditions and parental cell lines.

Animals↗
PubMed2002

Pharmacological characterization of the 5-HT receptors mediating contraction and relaxation of canine isolated proximal stomach smooth muscle.

1. We aimed to characterize 5-HT receptors mediating contraction and relaxation to 5-HT in dog proximal stomach longitudinal muscle (LM) strips. 2. Of the tryptamine analogues tested, 5-HT was the most potent contractile agent at basal length, while 5-CT was the most potent relaxant of PGF(2alpha)-induced contraction. Neither the contractions to 5-HT, nor the relaxations to 5-CT were influenced by tetrodotoxin, illustrating that action potential propagation is not involved. 3. The 5-HT-induced contraction was antagonized by mesulergine (0.03 to 0.3 microM) and ketanserin (2 - 20 nM), but the antagonism was not of a simple competitive nature, indicating multiple receptor involvement. Ketanserin (3 to 30 nM) and mesulergine (30 nM) competitively antagonized the alpha-Me-5-HT-induced contraction (pK(B): 8.83+/-0.09 and pA(2): 8.25+/-0.06 respectively). These affinity values are in line with literature affinities of ketanserin and mesulergine at 5-HT(2A) receptors in various bioassays. 4. The 5-CT-induced inhibition of PGF(2alpha)-induced contraction was competitively antagonized by mesulergine (pK(B) estimate: 8.52+/-0.12) and by the selective 5-HT(7) receptor antagonist SB-269970 (pK(B) estimate: 9.36+/-0.14). Both pK(B) estimates are in line with literature affinities of these compounds for 5-HT(7) receptors. Mesulergine (30 nM) and SB-269970 (10 nM) shifted the relaxant curve to 5-HT parallel to the right in the presence of ketanserin (0.3 microM) (pA(2) estimates of 8.08+/-0.10 and 8.75+/-0.14 respectively), indicative of 5-HT(7) receptor involvement. 5. It is concluded that 5-HT induces dog proximal stomach (LM) contraction via smooth muscle 5-HT(2A) receptors and relaxation via smooth muscle 5-HT(7) receptors.

Animals↗
PubMed2003

Involvement of glutamate and gamma-amino-butyric acid receptor systems on gastric acid secretion induced by activation of kappa-opioid receptors in the central nervous system in rats.

1. Various neurotransmitters in the brain regulate gastric acid secretion. Previously, we reported that the central injection of kappa-opioid receptor agonists stimulated this secretion in rats. Although the existence of kappa(1)-kappa(3)-opioid receptor subtypes has been proposed, the character is not defined. We investigated the interactions between kappa-opioid receptor subtypes and glutamate, gamma-amino-butyric acid (GABA) or 5-hydroxy tryptamine (5-HT) receptors in the rat brain. 2. Gastric acid secretion induced by the injection of U69593 (8.41 nmol, a putative kappa(1)-opioid receptor agonist) into the lateral cerebroventricle was completely inhibited by the central injection of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 10.9 nmol, an antagonist for non-N-methyl-D-aspartate (non-NMDA) receptors) and by bicuculline infusion (222 micro g kg(-1) per 10 min, i.v., GABA(A) receptor antagonist). The secretion induced by bremazocine (8.52 nmol, a putative kappa(2)-opioid receptor agonist) was inhibited by bicuculline infusion, but not by CNQX. The secretion induced by naloxone benzoylhydrazone (224 nmol, a putative kappa(3)-opioid receptor agonist) was slightly and partially inhibited by CNQX and bicuculline. 3. Treatment with CNQX and bicuculline inhibited gastric acid secretion induced by the injection of dynorphin A-(1-17) into the lateral, but not the fourth, cerebroventricle. Antagonists for NMDA, GABA(B) and 5-HT(2/1C) receptors did not inhibit the secretions by kappa-opioid receptor agonists. 4. In rat brain regions close to the lateral cerebroventricle, kappa-opioid receptor systems (kappa(1)>kappa(3)>>kappa(2)) are regulated by the non-NMDA type of glutamate receptor system, and kappa(1)- and kappa(2)-opioid receptor systems are regulated by the GABA(A) receptor system. The present findings show pharmacological evidence for kappa-opioid receptor subtypes that regulate gastric acid secretion in the rat brain.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed2003

Dihydroergotamine and its metabolite, 8'-hydroxy-dihydroergotamine, as 5-HT1A receptor agonists in the rat brain.

1 In addition to stopping migraine attacks, dihydroergotamine (DHE) is an efficient drug for migraine prophylaxis. Whether 5-HT(1A) receptors could contribute to the latter action was assessed by investigating the effects of DHE and its metabolite, 8'-OH-DHE, on these receptors in the rat brain. 2 Membrane binding assays with [(3)H]8-OH-DPAT and [(3)H]WAY 100635 as radioligands showed that both DHE (IC(50)=28-30 nM) and 8'-OH-DHE (IC(50)=8-11 nM) are high-affinity 5-HT(1A) receptor ligands. 3 Both DHE and 8'-OH-DHE enhanced the specific binding of [(35)S]GTP-gamma-S to the dorsal raphe nucleus and the hippocampus in brain sections, but to a lower extent than 5-carboxamido-tryptamine (5-CT) in the latter area. 4 Both DHE (EC(50)=10.9+/-0.3 nM) and 8'-OH-DHE (EC(50)=30.4+/-0.8 nM) inhibited the firing of serotoninergic neurons in the dorsal raphe nucleus within brain stem slices. 5 Intracellular recording showed that 8'-OH-DHE was more potent than DHE to hyperpolarize CA1 pyramidal cells in rat hippocampal slices. 6 Both the stimulatory effects of DHE and 8'-OH-DHE on [(35)S]GTP-gamma-S binding and their electrophysiological effects were completely prevented by the selective 5-HT(1A) receptor antagonist WAY 100635. 7 As expected of 5-HT(1A) receptor partial agonists, DHE and 8'-OH-DHE prevented any subsequent hyperpolarization of CA1 pyramidal cells by 5-HT or 5-CT. 8 Through their actions at 5-HT(1A) auto- (in the dorsal raphe nucleus) and hetero-(notably in the hippocampus) receptors, DHE, and even more its metabolite 8'-OH-DHE, can exert both an inhibitory influence on neuronal excitability and anxiolytic effects which might contribute to their antimigraine prophylactic efficiency.

Animals↗
PubMed2005

Voltage-dependent inhibition of recombinant NMDA receptor-mediated currents by 5-hydroxytryptamine.

The effect of 5-HT and related indolealkylamines on heteromeric recombinant NMDA receptors expressed in Xenopus oocytes was investigated using the two-electrode voltage-clamp recording technique. In the absence of external Mg(2+) ions, 5-HT inhibited NMDA receptor-mediated currents in a concentration-dependent manner. The inhibitory effect of 5-HT was independent of the NR1a and NR2 subunit combination. The inhibition of glutamate-evoked currents by 5-HT was use- and voltage-dependent. The voltage sensitivity of inhibition for NR1a+NR2 subunit combinations by 5-HT was similar, exhibiting an e-fold change per approximately 20 mV, indicating that 5-HT binds to a site deep within the membrane electric field. The inhibition of the open NMDA receptor by external Mg(2+) and 5-HT was not additive, suggesting competition between Mg(2+) and 5-HT for a binding site in the NMDA receptor channel. The concentration-dependence curves for 5-HT and 5-methoxytryptamine (5-MeOT) inhibition of NMDA receptor-mediated currents are shifted to the right in the presence of external Mg(2+). The related indolealkylamines inhibited glutamate-evoked currents with the following order of inhibitory potency: 5-MeOT=5-methyltryptamine>tryptamine>7-methyltryptamine>5-HT>>tryptophan=melatonin. Taken together, these data suggest that 5-HT and related compounds can attenuate glutamate-mediated excitatory synaptic responses and may provide a basis for drug treatment of excitoxic neurodegeneration.

Algorithms↗
PubMedDate not supplied

Pharmacologic analysis of non-synonymous coding h5-HT2A SNPs reveals alterations in atypical antipsychotic and agonist efficacies.

The 5-HT(2A)-serotonin receptor is a major molecular target for most atypical antipsychotic drugs as well as most hallucinogens, which can exacerbate psychotic symptoms. In this study, we examined whether random sequence variations in the gene (single nucleotide polymorphisms, SNPs) encoding the 5-HT(2A)-serotonin receptor could explain inter-individual variability in atypical antipsychotic and agonist drug response. We examined the in vitro pharmacology of four non-synonymous SNPs, which give rise to T25N, I197V, A447V, and H452Y variant 5-HT(2A)-serotonin receptors. Our data indicate that these non-synonymous SNPs exert statistically significant, although modest, effects on the affinity and functional effects of several currently approved atypical antipsychotics (aripiprazole, clozapine, olanzapine, quetiapine, risperidone, and ziprasidone). Also, the 5-HT(2A) receptor SNPs slightly altered the potency and relative efficacy of a small number of selected agonists (2,5-dimethoxy-4-iodoamphetamine, tryptamine, 5-hydroxytryptamine, m-chlorophenylpiperazine, and 5-methoxy-N, N-dimethyltryptamine). In all, our results show that the in vitro pharmacological effects of the SNPs are drug specific.

Antipsychotic Agents↗
PubMed1994

Biogenic amines in table olives. Analysis by high-performance liquid chromatography.

Biogenic amines in fermented vegetables have scarcely been studied. Available data show that in table olives and fermented cucumbers their presence is rare and any determinations made have been restricted mainly to histamine. However, some microorganisms, especially those related to spoilage, found in the fermentation brines of such products may have amino acid decarboxylase activity and give rise to biogenic amines by unusual processes. A method for the simultaneous determination of eight biogenic amines (tryptamine, beta-phenylethylamine, putrescine, cadaverine, histamine, tyramine, spermidine, and spermine) has been developed to study their occurrence in fermented vegetables in more detail. The method consists of extraction of the amines from olive paste with 5% m/v trichloracetic acid and successive transfers into water-saturated n-BuOH and 0.1 mol l-1 HCl. An aliquot of this mixture is dried and derivatized with dansyl chloride. The dansyl derivatives are then analysed by high-performance liquid chromatography. Special emphasis has been given to optimization of the n-BuOH and 0.1 mol l-1 HCl extractions and to the derivatization conditions. By applying this method to the analysis of spoilt olives, the presence of some biogenic amines has been demonstrated. Thus a new method for monitoring the presence of biogenic amines during the fermentation of olives and for detecting anomalous fermentations is envisaged.

Biogenic Amines↗
PubMed2005

Rotationally resolved electronic spectroscopy of tryptophol in the gas phase.

High resolution S1-S0 fluorescence excitation spectra of tryptophol have been observed in the collision-free environment of a supersonic beam. Each origin band has been assigned to a unique conformer based on its observed rotational constants. Unlike its close relative tryptamine, which exhibits seven distinguishable conformers under similar conditions, tryptophol exhibits only four (GPy-in, GPh-in, and two anti structures). Possible reasons for this difference in behavior are discussed.

Gases↗
PubMed2005

The diazo route to diazonamide A: studies on the tyrosine-derived fragment.

Various approaches to the tyrosine-derived fragment of the marine secondary metabolite diazonamide A are described. Initial efforts were focused on the originally proposed structure of the natural product, and a feasibility study established that a model 4-aryltryptamine could be readily prepared. Protected 4-bromotryptamine underwent Pd0-catalyzed coupling with the boronic acid derived from 2-bromophenyl allyl ether by Claisen rearrangement, O-methylation and lithiation-boration. The resulting biaryl was elaborated into an alpha-diazo-beta-ketoester, dirhodium(II)-catalyzed reaction of which with N-Z-valinamide gave the desired tryptamine-oxazole following cyclodehydration of the intermediate ketoamide. A potential precursor to the benzofuran ring of the original structure of diazonamide A was prepared in eight steps from N-Z-tyrosine tert-butyl ester. Iodination, O-protection and Stille coupling gave the cinnamyl alcohol 25, converted via the bromide into the allyl aryl ether 27. Subsequent Claisen rearrangement and oxidative cleavage of the alkene gave the lactol 29, converted into the desired benzofuranone 31. The revision in the structure of diazonamide A to 2 resulted in the targeting of an alternative tyrosine-derived model benzofuranone 41 synthesized in four steps from N-Z-tyrosine methyl ester 36 by a route involving Claisen rearrangement of cinnamyl ether 37. Poor yields in this sequence prompted an investigation into the intramolecular Heck reaction as a route to benzofuranone 50. Coupling of 3-iodotyrosine 44 with 2-phenylbutenoic acid 48 gave ester 49 that readily underwent intramolecular Heck reaction to give benzofuranone 50, albeit with poor stereocontrol.

Crystallography, X-Ray↗
PubMed2006

Studies in sigmatropic rearrangements of N-prenylindole derivatives--a formal enantiomerically pure synthesis of tryprostatin B.

Rearrangement of N(a)-prenyl-N(b)-acetyltryptamine, induced by BF3.Et2O at low temperature, leads to a 2-prenyl derivative, and thence to the tricyclic tryptamine 7 and the indoline 8. Similarly, N(a)-prenyl-N(b)-phthaloyl-l-tryptophan methyl ester furnished the corresponding 2-prenyl derivative 16, a known advanced precursor of tryprostatin B. Density functional (B3LYP) calculations for the putative rearrangement transition state for N-prenylskatole show that prior coordination of BF3 to the indolic nitrogen changes the character of the subsequent sigmatropic pericyclic shifts from being entirely covalent to acquiring a significant degree of ionic character. The shifting prenyl group favours the endo over the exo mode of the transition state by 4.1 kcal mol(-1).

Catalysis↗
PubMed1965

5-HYDROXYTRYPTAMINE METABOLISM BY THE NUCLEAR FRACTION OF RAT-LIVER HOMOGENATE.

1. The metabolism of 5-hydroxy[1'-(14)C]tryptamine creatinine sulphate in the nuclear fraction of rat-liver homogenate was studied. In the incubation mixture five metabolites were found. 2. Two metabolites were not radioactive; one of them was identified as 5-hydroxyindole-3-carboxylic acid and the second tentatively as 5-hydroxyindole-3-aldehyde. 3. 5-Hydroxyindol-3-ylacetic acid, 1'-N-acetyl-5-hydroxytryptamine and 5-hydroxytryptophol were not precursors of 5-hydroxyindolealdehyde and 5-hydroxyindolecarboxylic acid. 4. It was shown that the metabolism of 5-hydroxytryptamine in the nuclear fraction involves monoamine oxidase, the precursor of 5-hydroxyindolealdehyde and 5-hydroxyindolecarboxylic acid being most probably 5-hydroxyindol-3-ylacetaldehyde.

Aldehydes↗
PubMed1975

Specific binding sites for 5-hydroxytryptamine on rat blood platelets.

5-Hydroxytryptamine changes the shape of rat blood platelets by combination with a cinanserin-sensitive receptor which is not associated with the active uptake of 5-hydroxytryptamine. Binding of 5-hydroxy[3H]tryptamine to platelets at 4 degrees C demonstrates the presence of three saturable sites, and the highest-affinity site is apparently this 5-hydroxytryptamine receptor.

Animals↗

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