Biomaterial Database

Ca(2+)-dependent Cl- conductance in taste cells from Necturus. 1994

R Taylor, and S Roper

Department of Anatomy and Neurobiology, Colorado State University, Ft. Collins 80523.

1. Taste responses adapt to a constant chemical stimulus. The present study describes a new ionic conductance in taste cells--a Ca(2+)-dependent anion conductance that may explain taste adaptation. 2. Patch-clamp recordings were made on isolated Necturus taste cells or on taste cells in lingual slices. When Na+ and K+ currents were eliminated with tetrodotoxin (TTX) and tetraethyl-ammonium (TEA) in the bath and replacing K+ with N-methyl-D-glucamine (NMDG+) in the pipette, Ca2+ currents were followed by prolonged outward currents. Outward current was abolished when Ca2+ was substituted with Ba2+ or when Cl- was replaced with large organic anions (methanesulfonate, isethionate, or ascorbate). 3. The outward, Ca-dependent current was reduced by certain agents that block Cl- conductances in other tissues, namely 4-acet-amido-4-isothiocyanostilbene-2,2-disulfonic acid (SITS) and 4,4-diisothiocyanostilbene-2,2-disulfonic acid (DIDS). However, other Cl- channel blockers--9-AC, furosemide and an antibody to Cl channels-had little or no specific effect on the Ca-dependent outward current in Necturus taste cells. 4. We postulate that the biological action of this Ca-dependent anion conductance in situ is to terminate depolarizing receptor potentials, even during maintained chemostimulation, thereby playing an important role in chemosensory adaptation and modulation of impulse discharge patterns in taste buds.

UI	MeSH Term	Description	Entries
D008564	Membrane Potentials	The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).	Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D009337	Necturus	A genus of the Proteidae family with five recognized species, which inhabit the Atlantic and Gulf drainages.	Mudpuppy,Mudpuppies
D009435	Synaptic Transmission	The communication from a NEURON to a target (neuron, muscle, or secretory cell) across a SYNAPSE. In chemical synaptic transmission, the presynaptic neuron releases a NEUROTRANSMITTER that diffuses across the synaptic cleft and binds to specific synaptic receptors, activating them. The activated receptors modulate specific ion channels and/or second-messenger systems in the postsynaptic cell. In electrical synaptic transmission, electrical signals are communicated as an ionic current flow across ELECTRICAL SYNAPSES.	Neural Transmission,Neurotransmission,Transmission, Neural,Transmission, Synaptic
D011188	Potassium	An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.
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
D000344	Afferent Pathways	Nerve structures through which impulses are conducted from a peripheral part toward a nerve center.	Afferent Pathway,Pathway, Afferent,Pathways, Afferent
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
D013650	Taste Buds	Small sensory organs which contain gustatory receptor cells, basal cells, and supporting cells. Taste buds in humans are found in the epithelia of the tongue, palate, and pharynx. They are innervated by the CHORDA TYMPANI NERVE (a branch of the facial nerve) and the GLOSSOPHARYNGEAL NERVE.	Bud, Taste,Buds, Taste,Taste Bud
D013652	Taste Threshold	The minimum concentration at which taste sensitivity to a particular substance or food can be perceived.	Taste Thresholds,Threshold, Taste,Thresholds, Taste
D018118	Chloride Channels	Cell membrane glycoproteins that form channels to selectively pass chloride ions. Nonselective blockers include FENAMATES; ETHACRYNIC ACID; and TAMOXIFEN.	CaCC,Calcium-Activated Chloride Channel,Chloride Ion Channel,Chlorine Channel,Ion Channels, Chloride,CaCCs,Calcium-Activated Chloride Channels,Chloride Channel,Chloride Ion Channels,Chlorine Channels,Ion Channel, Chloride,Calcium Activated Chloride Channel,Calcium Activated Chloride Channels,Channel, Calcium-Activated Chloride,Channel, Chloride,Channel, Chloride Ion,Channel, Chlorine,Channels, Calcium-Activated Chloride,Channels, Chloride,Channels, Chloride Ion,Channels, Chlorine,Chloride Channel, Calcium-Activated,Chloride Channels, Calcium-Activated