Biomaterial Database

Heterogeneous calcium currents and transmitter release in cultured mouse spinal cord and dorsal root ganglion neurons. 1992

C Yu, and P X Lin, and S Fitzgerald, and P Nelson

Laboratory of Developmental Neurobiology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892.

1. Calcium currents and transmitter release were studied in cocultures of fetal mouse neurons from the ventral half of the spinal cord (VH neurons) and from dorsal root ganglion (DRG neurons). The effects of BayK 8644 and omega-conotoxin on calcium currents and transmitter release were compared. 2. The presence of low voltage-activated (LVA) calcium current in both VH and DRG neurons is variable. Some cells exhibit only high voltage-activated (HVA) currents, whereas others show both HVA and LVA currents. 3. BayK 8644 did not affect LVA currents but strongly augmented both steady and transient components of the HVA calcium conductance. 4. omega-Conotoxin GVIA reduces both transient and steady components of the HVA but does not abolish either component even after 3 h of application. 5. Calcium currents that were resistant to omega-contoxin were augmented by BayK 8644. 6. Synaptic transmission between pairs of spinal cord neurons from the ventral half of the spinal cord (VH-VH connections) or between dorsal root ganglion neurons and VH neurons (DRG-VH connections) were studied with two-cell recording and stimulation techniques. 7. In approximately 70% of VH-VH connections and 50% of DRG-VH connections, BayK 8644 or its active optical isomer failed to affect transmitter output. Substantial augmentation of the remainder of the connections could be reliably produced by the dihydropyridines. Raised calcium in the extracellular medium produced augmentation of synaptic connections in all cases. BayK 8644 produced substantial, consistent augmentation of voltage-sensitive calcium channels in both VH and DRG neurons. 8. The toxin, omega-conotoxin, produced no consistent effect on excitatory or inhibitory postsynaptic potentials (EPSPs or IPSPs) elicited in VH neurons by stimulation of nearby VH neurons. VH EPSPs elicited by stimulation of nearby DRG neurons were reduced to approximately 50% of control values after 10 min of omega-conotoxin perfusion. Spontaneous and evoked synaptic activity could be recorded in VH neurons as long as 2 h after cultures were incubated in 0.5 microM omega-conotoxin. omega-Conotoxin produced a modest reduction in HVA currents in both VH and DRG neurons. 9. BayK 8644 did not produce consistent augmentation of transmission at the frog neuromuscular junction. omega-Conotoxin produced total blockade of transmission in this preparation. 10. We conclude that neither sustained nor inactivating high-threshold voltage-sensitive (HVA) calcium channels sensitive to BayK 8644 or omega-conotoxin such as those measured in the neuronal cell bodies are responsible for action-potential-evoked transmitter release from the majority of VH neurons.(ABSTRACT TRUNCATED AT 400 WORDS)

UI	MeSH Term	Description	Entries
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
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
D010456	Peptides, Cyclic	Peptides whose amino acid residues are linked together forming a circular chain. Some of them are ANTI-INFECTIVE AGENTS; some are biosynthesized non-ribosomally (PEPTIDE BIOSYNTHESIS, NON-RIBOSOMAL).	Circular Peptide,Cyclic Peptide,Cyclic Peptides,Cyclopeptide,Orbitide,Circular Peptides,Cyclopeptides,Orbitides,Peptide, Circular,Peptide, Cyclic,Peptides, Circular
D002121	Calcium Channel Blockers	A class of drugs that act by selective inhibition of calcium influx through cellular membranes.	Calcium Antagonists, Exogenous,Calcium Blockaders, Exogenous,Calcium Channel Antagonist,Calcium Channel Blocker,Calcium Channel Blocking Drug,Calcium Inhibitors, Exogenous,Channel Blockers, Calcium,Exogenous Calcium Blockader,Exogenous Calcium Inhibitor,Calcium Channel Antagonists,Calcium Channel Blocking Drugs,Exogenous Calcium Antagonists,Exogenous Calcium Blockaders,Exogenous Calcium Inhibitors,Antagonist, Calcium Channel,Antagonists, Calcium Channel,Antagonists, Exogenous Calcium,Blockader, Exogenous Calcium,Blocker, Calcium Channel,Blockers, Calcium Channel,Calcium Blockader, Exogenous,Calcium Inhibitor, Exogenous,Channel Antagonist, Calcium,Channel Blocker, Calcium,Inhibitor, Exogenous Calcium
D002478	Cells, Cultured	Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.	Cultured Cells,Cell, Cultured,Cultured Cell
D003470	Culture Media	Any liquid or solid preparation made specifically for the growth, storage, or transport of microorganisms or other types of cells. The variety of media that exist allow for the culturing of specific microorganisms and cell types, such as differential media, selective media, test media, and defined media. Solid media consist of liquid media that have been solidified with an agent such as AGAR or GELATIN.	Media, Culture
D005727	Ganglia, Spinal	Sensory ganglia located on the dorsal spinal roots within the vertebral column. The spinal ganglion cells are pseudounipolar. The single primary branch bifurcates sending a peripheral process to carry sensory information from the periphery and a central branch which relays that information to the spinal cord or brain.	Dorsal Root Ganglia,Spinal Ganglia,Dorsal Root Ganglion,Ganglion, Spinal,Ganglia, Dorsal Root,Ganglion, Dorsal Root,Spinal Ganglion
D000200	Action Potentials	Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.	Spike Potentials,Nerve Impulses,Action Potential,Impulse, Nerve,Impulses, Nerve,Nerve Impulse,Potential, Action,Potential, Spike,Potentials, Action,Potentials, Spike,Spike Potential
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
D001001	Anura	An order of the class Amphibia, which includes several families of frogs and toads. They are characterized by well developed hind limbs adapted for jumping, fused head and trunk and webbed toes. The term "toad" is ambiguous and is properly applied only to the family Bufonidae.	Bombina,Frogs and Toads,Salientia,Toad, Fire-Bellied,Toads and Frogs,Anuras,Fire-Bellied Toad,Fire-Bellied Toads,Salientias,Toad, Fire Bellied,Toads, Fire-Bellied