Biomaterial Database

Presynaptic calcium diffusion and the time courses of transmitter release and synaptic facilitation at the squid giant synapse. 1983

R S Zucker, and N Stockbridge

At the squid giant synapse, a presynaptic action potential is accompanied by an influx of calcium ions that continue to be detectable with arsenazo III microspectrophotometry for several seconds. Nevertheless, transmitter release occurs phasically, lasting only about 2 msec. If a second action potential follows within about 100 msec after the first, it releases more transmitter. In this paper, we present a mathematical model of intracellular calcium diffusion with binding to fixed cytoplasmic sites, active extrusion at the surface, and influx during an action potential, to predict the distribution of intracellular calcium following an action potential. With a square law relation between submembrane calcium and transmitter release, the model predicts the phasic release of transmitter and the magnitude and time course of synaptic facilitation following an action potential, as well as the relatively long persistence of free intracellular calcium.

UI	MeSH Term	Description	Entries
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
D004058	Diffusion	The tendency of a gas or solute to pass from a point of higher pressure or concentration to a point of lower pressure or concentration and to distribute itself throughout the available space. Diffusion, especially FACILITATED DIFFUSION, is a major mechanism of BIOLOGICAL TRANSPORT.	Diffusions
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
D001048	Aplysia	An opisthobranch mollusk of the order Anaspidea. It is used frequently in studies of nervous system development because of its large identifiable neurons. Aplysiatoxin and its derivatives are not biosynthesized by Aplysia, but acquired by ingestion of Lyngbya (seaweed) species.	Aplysias
D001369	Axons	Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body.	Axon
D013569	Synapses	Specialized junctions at which a neuron communicates with a target cell. At classical synapses, a neuron's presynaptic terminal releases a chemical transmitter stored in synaptic vesicles which diffuses across a narrow synaptic cleft and activates receptors on the postsynaptic membrane of the target cell. The target may be a dendrite, cell body, or axon of another neuron, or a specialized region of a muscle or secretory cell. Neurons may also communicate via direct electrical coupling with ELECTRICAL SYNAPSES. Several other non-synaptic chemical or electric signal transmitting processes occur via extracellular mediated interactions.	Synapse
D013997	Time Factors	Elements of limited time intervals, contributing to particular results or situations.	Time Series,Factor, Time,Time Factor
D049832	Decapodiformes	A superorder of CEPHALOPODS comprised of squid, cuttlefish, and their relatives. Their distinguishing feature is the modification of their fourth pair of arms into tentacles, resulting in 10 limbs.	Cuttlefish,Illex,Sepiidae,Squid,Todarodes,Cuttlefishs,Decapodiforme,Illices,Squids,Todarode
D018377	Neurotransmitter Agents	Substances used for their pharmacological actions on any aspect of neurotransmitter systems. Neurotransmitter agents include agonists, antagonists, degradation inhibitors, uptake inhibitors, depleters, precursors, and modulators of receptor function.	Nerve Transmitter Substance,Neurohormone,Neurohumor,Neurotransmitter Agent,Nerve Transmitter Substances,Neurohormones,Neurohumors,Neuromodulator,Neuromodulators,Neuroregulator,Neuroregulators,Neurotransmitter,Neurotransmitters,Substances, Nerve Transmitter,Transmitter Substances, Nerve,Substance, Nerve Transmitter,Transmitter Substance, Nerve