Biomaterial Database

Voltage-activated calcium currents in presynaptic nerve terminals of the chicken ciliary ganglion. 1990

H Yawo

Department of Physiology, Kyoto University Faculty of Medicine, Japan.

1. Calcium currents (ICa) were recorded from presynaptic calyces of ciliary ganglia of the chick embryo under whole-cell voltage clamp. 2. Only high-threshold ICa was recorded without any evidence for the presence of low-threshold Ca2+ channels. 3. High-threshold (high-voltage-activated, HVA) ICa could be classified into non-inactivating (HVAn) and inactivating (HVAi) components. The mean inactivation time constant of the HVAi component was 213 ms (at 0 mV). The threshold for activation by depolarizing pulses was more negative for the HVAn component than for the HVAi component. The HVAi component was inactivated by 19% at a holding potential of -60 mV, while the HVAn component was little affected under this condition. 4. The activation of HVAn component was faster than that of the HVAi component. 5. Both the HVAn and HVAi components were blocked by Cd2+ (50 microM) and La3+ (1 microM). Both components were only slightly affected by Ni2+ (100 microM). The order of potency in blocking was La3+ greater than Cd2+ greater than Ni2+ for both components. Both the HVAi and HVAn components were irreversibly blocked by omega-conotoxin GVIA(omega-CgTX, 10 microM). 6. The two components could pharmacologically be distinguished by selective blockade of the HVAn component with nifedipine (2 microM) and D600 (100-250 microM). 7. HVAn and HVAi components are suggested to represent two different subpopulations of Ca2+ channels. The HVAn subpopulation may be responsible for persistent Ca2+ influx during subthreshold depolarization of the nerve terminal.

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
D009411	Nerve Endings	Branch-like terminations of NERVE FIBERS, sensory or motor NEURONS. Endings of sensory neurons are the beginnings of afferent pathway to the CENTRAL NERVOUS SYSTEM. Endings of motor neurons are the terminals of axons at the muscle cells. Nerve endings which release neurotransmitters are called PRESYNAPTIC TERMINALS.	Ending, Nerve,Endings, Nerve,Nerve Ending
D002642	Chick Embryo	The developmental entity of a fertilized chicken egg (ZYGOTE). The developmental process begins about 24 h before the egg is laid at the BLASTODISC, a small whitish spot on the surface of the EGG YOLK. After 21 days of incubation, the embryo is fully developed before hatching.	Embryo, Chick,Chick Embryos,Embryos, Chick
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.
D005726	Ganglia, Parasympathetic	Ganglia of the parasympathetic nervous system, including the ciliary, pterygopalatine, submandibular, and otic ganglia in the cranial region and intrinsic (terminal) ganglia associated with target organs in the thorax and abdomen.	Parasympathetic Ganglia,Ciliary Ganglion,Ganglion, Parasympathetic,Otic Ganglia,Pterygopalatine Ganglia,Submandibular Ganglia,Ciliary Ganglions,Ganglia, Otic,Ganglia, Pterygopalatine,Ganglia, Submandibular,Ganglias, Otic,Ganglias, Pterygopalatine,Ganglias, Submandibular,Ganglion, Ciliary,Ganglions, Ciliary,Otic Ganglias,Parasympathetic Ganglion,Pterygopalatine Ganglias,Submandibular Ganglias
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
D015220	Calcium Channels	Voltage-dependent cell membrane glycoproteins selectively permeable to calcium ions. They are categorized as L-, T-, N-, P-, Q-, and R-types based on the activation and inactivation kinetics, ion specificity, and sensitivity to drugs and toxins. The L- and T-types are present throughout the cardiovascular and central nervous systems and the N-, P-, Q-, & R-types are located in neuronal tissue.	Ion Channels, Calcium,Receptors, Calcium Channel Blocker,Voltage-Dependent Calcium Channel,Calcium Channel,Calcium Channel Antagonist Receptor,Calcium Channel Antagonist Receptors,Calcium Channel Blocker Receptor,Calcium Channel Blocker Receptors,Ion Channel, Calcium,Receptors, Calcium Channel Antagonist,VDCC,Voltage-Dependent Calcium Channels,Calcium Channel, Voltage-Dependent,Calcium Channels, Voltage-Dependent,Calcium Ion Channel,Calcium Ion Channels,Channel, Voltage-Dependent Calcium,Channels, Voltage-Dependent Calcium,Voltage Dependent Calcium Channel,Voltage Dependent Calcium Channels
D015640	Ion Channel Gating	The opening and closing of ion channels due to a stimulus. The stimulus can be a change in membrane potential (voltage-gated), drugs or chemical transmitters (ligand-gated), or a mechanical deformation. Gating is thought to involve conformational changes of the ion channel which alters selective permeability.	Gating, Ion Channel,Gatings, Ion Channel,Ion Channel Gatings