Biomaterial Database

[Synaptic interaction of individual motor neurons of the isolated frog spinal cord]. 1984

A I Shapovalov, and B I Shiriaev

The mode of synaptic transmission between single lumbar motoneurons in isolated spinal cord of frog was investigated by means of parallel penetration of two separate microelectrodes in two neighbouring motoneurons. The synaptic transmission between them was electrically mediated in 82 of 89 cases studied, which was indicated by the lack or very short latency of unitary intermotoneuronal EPSPs and by its amplitude persistence in Ca2+-free, Mn2+-containing solution. Effective electrotonic spread in either direction was demonstrated: both depo- and hyperpolarizing currents passed through an electrode in one motoneuron produced corresponding potentials in coupled motoneuron. The rise and decay of these potentials have much longer time constant as compared to time constant of both coupled motoneurons. The blockade of SD-component of an action potential in "trigger" motoneuron produced a decrease in the EPSP amplitude in the coupled motoneuron. Electrotonic synapses between motoneurons revealed no rectification. In four cases unitary intermotoneuronal EPSPs were chemically mediated as was indicated by their latencies (1.3-3.3 ms) and by their full blockade in CA2+-free, Mn2+-containing solution. The amplitude of this group of EPSPs fluctuated in accordance with binomial or Poisson statistics. In three cases double-component unitary intermotoneuronal EPSPs were recorded, first and second components of which were electrically and chemically mediated, respectively. Morphological structures which could be responsible for the generation of these three groups of unitary EPSPs are considered.

UI	MeSH Term	Description	Entries
D009046	Motor Neurons	Neurons which activate MUSCLE CELLS.	Neurons, Motor,Alpha Motorneurons,Motoneurons,Motor Neurons, Alpha,Neurons, Alpha Motor,Alpha Motor Neuron,Alpha Motor Neurons,Alpha Motorneuron,Motoneuron,Motor Neuron,Motor Neuron, Alpha,Motorneuron, Alpha,Motorneurons, Alpha,Neuron, Alpha Motor,Neuron, Motor
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
D011895	Rana ridibunda	A species of the family Ranidae which occurs primarily in Europe and is used widely in biomedical research.
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
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
D000870	Anterior Horn Cells	MOTOR NEURONS in the anterior (ventral) horn of the SPINAL CORD which project to SKELETAL MUSCLES.	Anterior Horn Neurons,Neurons, Anterior Horn,Neurons, Ventral Horn,Ventral Horn Cells,Ventral Horn Neurons,Anterior Horn Cell,Anterior Horn Neuron,Cell, Anterior Horn,Cell, Ventral Horn,Cells, Anterior Horn,Cells, Ventral Horn,Neuron, Anterior Horn,Neuron, Ventral Horn,Ventral Horn Cell,Ventral Horn Neuron
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