Biomaterial Database

Adenine nucleotides in cholinergic transmission: presynaptic aspects. 1978

M J Dowdall

1. Isolated nerve terminals (T-sacs and synaptosomes) prepared from the purely cholinergic Torpedo electric organ have been studied for their ability to incorporate and metabolise [2-3H] adenosine and to degrade 5'-AMP to adenosine. 2. A temperature-dependent, saturable uptake system for adenosine was found with kinetic properties similar to nucleoside transport systems in other cells. The uptake system in Torpedo nerve terminals was inhibited by 2'-deoxyadenosine, a known inhibitor of adenosine transport. 3. Intraterminal adenosine is rapidly metabolised to a number of products including AMP, ADP and ATP. 4. Isolated nerve terminals contain considerable 5'-nucleotidase activity, most of which resides on the outer face of the external membrane. The Km of the enzyme is congruent to 5 micron and it is inhibited by a phosphonate analogue of ADP, alpha-beta-methylene-ADP. It is suggested that this 5'-nucleotidase plays an important role in the production of adenosine from a nucleotide pool in the synaptic cleft.

UI	MeSH Term	Description	Entries
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
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
D009469	Neuromuscular Junction	The synapse between a neuron and a muscle.	Myoneural Junction,Nerve-Muscle Preparation,Junction, Myoneural,Junction, Neuromuscular,Junctions, Myoneural,Junctions, Neuromuscular,Myoneural Junctions,Nerve Muscle Preparation,Nerve-Muscle Preparations,Neuromuscular Junctions,Preparation, Nerve-Muscle,Preparations, Nerve-Muscle
D009708	Nucleotidases	A class of enzymes that catalyze the conversion of a nucleotide and water to a nucleoside and orthophosphate. EC 3.1.3.-.
D002799	Cholinergic Fibers	Nerve fibers liberating acetylcholine at the synapse after an impulse.	Cholinergic Fiber,Fiber, Cholinergic,Fibers, Cholinergic
D004557	Electric Organ	In about 250 species of electric fishes, modified muscle fibers forming disklike multinucleate plates arranged in stacks like batteries in series and embedded in a gelatinous matrix. A large torpedo ray may have half a million plates. Muscles in different parts of the body may be modified, i.e., the trunk and tail in the electric eel, the hyobranchial apparatus in the electric ray, and extrinsic eye muscles in the stargazers. Powerful electric organs emit pulses in brief bursts several times a second. They serve to stun prey and ward off predators. A large torpedo ray can produce of shock of more than 200 volts, capable of stunning a human. (Storer et al., General Zoology, 6th ed, p672)	Electric Organs,Organ, Electric,Organs, Electric
D005399	Fishes	A group of cold-blooded, aquatic vertebrates having gills, fins, a cartilaginous or bony endoskeleton, and elongated bodies covered with scales.
D000227	Adenine Nucleotides		Adenine Nucleotide,Adenosine Phosphate,Adenosine Phosphates,Nucleotide, Adenine,Nucleotides, Adenine,Phosphate, Adenosine,Phosphates, Adenosine
D000241	Adenosine	A nucleoside that is composed of ADENINE and D-RIBOSE. Adenosine or adenosine derivatives play many important biological roles in addition to being components of DNA and RNA. Adenosine itself is a neurotransmitter.	Adenocard,Adenoscan
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