Biomaterial Database

Ligand-gated ion channels opened by 5-HT in molluscan neurones. 1996

K A Green, and J J Lambert, and G A Cottrell

School of Biological and Medical Sciences, St. Andrews, Fife.

1. 5-Hydroxytryptamine (5-HT) activated a fast (70 ms to half maximum) and desensitizing inward current through non-selective channels conducting predominantly monovalent cations in neurons of Helix aspersa. 2. alpha-Methyl-5-HT was equipotent with 5-HT in activating this current, but the known selective agonists at vertebrate 5-HT3 receptors, 2-methyl-5-HT and arylbiguanides were ineffective (< 100 microM). 5-Methoxytryptamine which is inactive on vertebrate 5-HT3 receptors was a very weak agonist. 3. The responses were antagonized by the specific vertebrate 5-HT3 receptor blocker MDL-72222 (IC50 = 1 microM), but were only weakly affected by ondansetron (10 microM). The 5-HT2-type antagonist, ketanserin (< 5 microM) had no effect. The responses were also antagonized by the non-specific antagonists (+)-tubocurarine and strychnine. 4. Unitary currents through channels non-selective for monovalent cations, and with a conductance of 2pS, could be activated repeatedly by 5-HT or alpha-methyl-5-HT in outside-out patches from neurones exhibiting the fast 5-HT-activated current (I[5-HT]fast), even in the presence of 500 microM GDP-[beta S] in the recording pipette. This strongly supports direct-gating of these channels by 5-HT. The properties of these unitary currents resembled those of I[5-HT]fast. 5. The pharmacological properties of this molluscan 5-HT-operated, ligand-gated channel differed sufficiently from known vertebrate 5-HT3-type receptors to suggest that it represents a new class of 5-HT receptor.

UI	MeSH Term	Description	Entries
D007473	Ion Channels	Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.	Membrane Channels,Ion Channel,Ionic Channel,Ionic Channels,Membrane Channel,Channel, Ion,Channel, Ionic,Channel, Membrane,Channels, Ion,Channels, Ionic,Channels, Membrane
D007650	Ketanserin	A selective serotonin receptor antagonist with weak adrenergic receptor blocking properties. The drug is effective in lowering blood pressure in essential hypertension. It also inhibits platelet aggregation. It is well tolerated and is particularly effective in older patients.	3-(2-(4-(4-Fluorobenzoyl)piperidinol)ethyl)-2,4(1H,3H)-quinazolinedione,R-41,468,R-41468,R 41,468,R 41468,R41,468,R41468
D009474	Neurons	The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.	Nerve Cells,Cell, Nerve,Cells, Nerve,Nerve Cell,Neuron
D011985	Receptors, Serotonin	Cell-surface proteins that bind SEROTONIN and trigger intracellular changes which influence the behavior of cells. Several types of serotonin receptors have been recognized which differ in their pharmacology, molecular biology, and mode of action.	5-HT Receptor,5-HT Receptors,5-Hydroxytryptamine Receptor,5-Hydroxytryptamine Receptors,Receptors, Tryptamine,Serotonin Receptor,Serotonin Receptors,Tryptamine Receptor,Tryptamine Receptors,Receptors, 5-HT,Receptors, 5-Hydroxytryptamine,5 HT Receptor,5 HT Receptors,5 Hydroxytryptamine Receptor,5 Hydroxytryptamine Receptors,Receptor, 5-HT,Receptor, 5-Hydroxytryptamine,Receptor, Serotonin,Receptor, Tryptamine,Receptors, 5 HT,Receptors, 5 Hydroxytryptamine
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D003292	Convulsants	Substances that act in the brain stem or spinal cord to produce tonic or clonic convulsions, often by removing normal inhibitory tone. They were formerly used to stimulate respiration or as antidotes to barbiturate overdose. They are now most commonly used as experimental tools.	Convulsant,Convulsant Effect,Convulsant Effects,Effect, Convulsant,Effects, Convulsant
D004305	Dose-Response Relationship, Drug	The relationship between the dose of an administered drug and the response of the organism to the drug.	Dose Response Relationship, Drug,Dose-Response Relationships, Drug,Drug Dose-Response Relationship,Drug Dose-Response Relationships,Relationship, Drug Dose-Response,Relationships, Drug Dose-Response
D004594	Electrophysiology	The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.
D006372	Helix, Snails	A genus of chiefly Eurasian and African land snails including the principal edible snails as well as several pests of cultivated plants.	Helix (Snails),Snails Helix
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia