Biomaterial Database

Zinc permeates mouse muscle ACh receptor channels expressed in BOSC 23 cells and affects channel function. 2000

D Ragozzino, and A Giovannelli, and V Degasperi, and F Eusebi, and F Grassi

Istituto Pasteur-Fondazione Cenci Bolognetti and Dipartimento di Fisiologia Umana e Farmacologia, Universita 'La Sapienza', Rome, Italy.

1. The influx of Zn2+ through the channels of fetal and adult mouse muscle nicotinic acetylcholine receptors (gamma- and epsilon-AChRs) and its effects on receptor function were studied in transiently transfected human BOSC 23 cells, by combining patch-clamp recordings with digital fluorescence microscopy. 2. ACh-induced whole-cell currents were reversibly reduced by external ZnCl2, with half-maximal inhibitory concentrations of 3 and 1 mM for gamma- and epsilon-AChRs, respectively. 3. Both gamma- and epsilon-AChR channels were permeable to Zn2+, as shown by fluorescence measurements using Zn2+-sensitive dyes. The fractional current carried by Zn2+ (Pf,Zn; 0.5 mM Zn2+ in Ca2+- and Mg2+-free medium) through gamma- and epsilon">-AChR channels was 1.7 and 4 %, respectively. 4. Pf,Zn increased with the concentration of ZnCl2, but was little affected by physiological concentrations of Ca2+ and Mg2+ in the external medium. 5. The conductance of ACh-evoked unitary events, measured by cell-attached or outside-out recordings, decreased when the patched membrane was exposed to ZnCl2 (1 or 3 mM). Simultaneous application of ACh and Zn2+ to the extra-patch membrane lengthened channel open duration (tau op) by 50%. No obvious increment of tau op was observed following exposure of inside-out patches to Zn2+. 6. The possible physiological relevance of zinc-induced modulation of AChR channels is discussed.

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
D009538	Nicotine	Nicotine is highly toxic alkaloid. It is the prototypical agonist at nicotinic cholinergic receptors where it dramatically stimulates neurons and ultimately blocks synaptic transmission. Nicotine is also important medically because of its presence in tobacco smoke.	Nicotine Bitartrate,Nicotine Tartrate
D010539	Permeability	Property of membranes and other structures to permit passage of light, heat, gases, liquids, metabolites, and mineral ions.	Permeabilities
D011950	Receptors, Cholinergic	Cell surface proteins that bind acetylcholine with high affinity and trigger intracellular changes influencing the behavior of cells. Cholinergic receptors are divided into two major classes, muscarinic and nicotinic, based originally on their affinity for nicotine and muscarine. Each group is further subdivided based on pharmacology, location, mode of action, and/or molecular biology.	ACh Receptor,Acetylcholine Receptor,Acetylcholine Receptors,Cholinergic Receptor,Cholinergic Receptors,Cholinoceptive Sites,Cholinoceptor,Cholinoceptors,Receptors, Acetylcholine,ACh Receptors,Receptors, ACh,Receptor, ACh,Receptor, Acetylcholine,Receptor, Cholinergic,Sites, Cholinoceptive
D002460	Cell Line	Established cell cultures that have the potential to propagate indefinitely.	Cell Lines,Line, Cell,Lines, Cell
D004558	Electric Stimulation	Use of electric potential or currents to elicit biological responses.	Stimulation, Electric,Electrical Stimulation,Electric Stimulations,Electrical Stimulations,Stimulation, Electrical,Stimulations, Electric,Stimulations, Electrical
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.
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
D013050	Spectrometry, Fluorescence	Measurement of the intensity and quality of fluorescence.	Fluorescence Spectrophotometry,Fluorescence Spectroscopy,Spectrofluorometry,Fluorescence Spectrometry,Spectrophotometry, Fluorescence,Spectroscopy, Fluorescence
D015032	Zinc	A metallic element of atomic number 30 and atomic weight 65.38. It is a necessary trace element in the diet, forming an essential part of many enzymes, and playing an important role in protein synthesis and in cell division. Zinc deficiency is associated with ANEMIA, short stature, HYPOGONADISM, impaired WOUND HEALING, and geophagia. It is known by the symbol Zn.