Biomaterial Database

Progression of age changes in synaptic transmission at mouse neuromuscular junctions. 1983

S S Kelly, and N Robbins

The progression of age-related changes in neuromuscular function was investigated in muscles from CBF-1 mice between 7 and 32 months of age. End-plate potentials (e.p.p.s) were recorded in extensor digitorum longus (e.d.l.), soleus, and diaphragm muscles after neuromuscular transmission was blocked with either (+)-tubocurarine chloride (curare) or high-Mg/low-Ca Krebs solutions. Between 10 and 31 months of age in e.d.l. and soleus but not in diaphragm, there was an increase in e.p.p. amplitude with age. In soleus this increase was approximately two-fold in curare and three-fold in high-Mg solution. Increase in e.p.p. amplitude in curarized preparations took place between 20 and 28 months of age in e.d.l. and between 28 and 31 months of age in soleus. Indirectly elicited twitch responses were used to determine the time course of age-related changes in sensitivity to Mg block. Increased resistance to block appeared between 15 and 19 months of age in both e.d.l. and soleus (in which the increase was more gradual). E.d.l. muscles from 25-month-old CFW mice also showed an increased resistance to Mg block compared to those from 7-8-month-old animals. In Mg-blocked preparations, increased quantum content (measured directly) accounted for the increased e.p.p. amplitude. Spontaneous miniature end-plate potential (m.e.p.p.) frequency in old soleus muscles was not sensitive to low-Ca/high-Mg solutions although frequency in young soleus and young and old diaphragm was significantly reduced. It is concluded that age-related changes in evoked transmitter release begin in mid life and take place more rapidly in e.d.l. than in soleus.(ABSTRACT TRUNCATED AT 250 WORDS)

UI	MeSH Term	Description	Entries
D008274	Magnesium	A metallic element that has the atomic symbol Mg, atomic number 12, and atomic weight 24.31. It is important for the activity of many enzymes, especially those involved in OXIDATIVE PHOSPHORYLATION.
D008297	Male		Males
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
D009045	Motor Endplate	The specialized postsynaptic region of a muscle cell. The motor endplate is immediately across the synaptic cleft from the presynaptic axon terminal. Among its anatomical specializations are junctional folds which harbor a high density of cholinergic receptors.	Motor End-Plate,End-Plate, Motor,End-Plates, Motor,Endplate, Motor,Endplates, Motor,Motor End Plate,Motor End-Plates,Motor Endplates
D009132	Muscles	Contractile tissue that produces movement in animals.	Muscle Tissue,Muscle,Muscle Tissues,Tissue, Muscle,Tissues, Muscle
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
D000375	Aging	The gradual irreversible changes in structure and function of an organism that occur as a result of the passage of time.	Senescence,Aging, Biological,Biological Aging
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
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