Ganglionic action

TABLE 14.1 Type of Ganglionic Action Potential per Synapse Type... 

Neurotransmitter/Neuromodulator Ganglionic Receptor Ganglionic Action Potential... 

Mollusca and Arthropoda. A variety of pharmacological actions are induced by the toxins found in molluscs (17). For example, surugatoxin is a potent mydriatic (5J), ganglion blocker (84), and a potent hypotensive agent in cats. 

Figure 2.12 From voltage-clamp to current-clamp micro-electrode recordings of synaptic current (/, lower trace) and synaptic potential with superimposed action potential (V, upper trace) from a neuron in an isolated rat superior cervical sympathetic ganglion following a single stimulus (S) applied to the preganglionic nerve trunk. The interval between the stimulus and the postsynaptic response includes the conduction time along the unmyelinated axons of the preganglionic nerve trunk. (SJ Marsh and DA Brown, unpublished)...

When studying competitive antagonism, it is sometimes necessary to include an uptake inhibitor or a ganglion blocker in all the bathing solutions used. If this compound has in addition some competitive blocking action at the receptor being studied, what effect will this have on estimation of the dissociation equilibrium constant for a competitive antagonist ... 

Neurotrophin 4/5 is not as well characterized as other members of the neurotrophin family. Much of what is known is derived from analysis of NT4/5 and TrkB knockout mice. Elucidating the actions of NT4/5 is complicated by virtue of the fact that both NT4/5 and BDNF exert their effects via the TrkB receptor. It appears that NT4/5 functions largely overlap with those of other neurotrophin family members, particularly BDNF. NT4/5 knockout mice are essentially normal, in contrast to BDNF knockout mice, which do not live long. NT4/5 is likely to have unique actions on a subpopulation of neurons in the nodose and geniculate ganglia, which are not supported by BDNF. Like BDNF, NT4/5 acts on sensory neurons and retinal ganglion cells, supporting their survival. 

To summarize there are two learning paradigms in the context of a reflex action controlled by a single ganglion in an experimental animal in which electrical measurements of nerve action are relatively easy. This experimental system permitted Kandel to map the neural circuit responsible for the gill-withdrawal reflex. The neural... 

The Na" channel has a receptor site for cyclic GMP when cyclic GMP is bound, the channel is closed. This leads to a decrease in the intracellular Na ion concentration, resulting in hyperpolarisation of the cell membrane. This decreases the release of the neurotransmitter glutamate into the synapse that connects the photoreceptor cell to the bipolar neurones. In this specific case, a decrease in the neurotransmitter concentration in the synapse is a signal that results in depolarisation of the bipolar cell. The action potential in the bipolar cells communicate with ganglion cells, the axons of which form the optic nerve. Thus action potentials are generated in the axons which are... 

Depletion by guanidines, unlike depletion by reserpine, is not dependent on sympathetic innervation, and is unaffected by denervation of peripheral tissues [400], or by ganglionic blockade [264, 401]. The ability of some drugs to antagonize the depleting action of guanidines without appreciably reducing that of reserpine has been described earlier (p. 185). 

Spasmolysis by N-butylscopolamine in biUary or renal colic (p. 126). Because of its quaternary nitrogen, this drug does not enter the brain and requires parenteral administratioa Its spasmolytic action is especially marked because of additional ganglionic blocking and direct muscle-relaxant actions. 

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