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Glossary of Physiology Terms
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There are 9 glossary search results for:   sodium




Abbreviation:
Na+

Definition:
The main cation (positively charged ion) of the extracellular fluid.

Sodium (Na+) plays an important role in several physiological processes such as the action potential of neurons and muscle cells, secondary active, sodium-coupled transport of ions, nutrients, neurotransmitters across the plasma membrane of cells, and many other processes.

The extracellular concentration of Na+ is about 145 mM. The intracellular concentration of Na+ is about 15 mM.



Definition:
Amiloride inhibits epithelial Na+ channels (ENaC), and in doing so, it acts as a diuretic by inhibiting sodium reabsorption in the late distal convoluted tubules, connecting tubules, and collecting ducts in the kidneys.

Other resources:
Amiloride (Wikipedia)



Definition:
An integral membrane protein which contains a pore through which ions, water, or polar molecules permeate. For any given channel, the pore is usually very selective for the particular ion or molecule. For example, sodium (Na+) channels are very selective for Na+ over other cations.

The channel pore may be constitutively open, or it may be gated to the open state by various stimuli such as chemical ligands, voltage, temperature, or mechanical stimulation of the membrane.



Definition:
Electrogenic pumps are primary active transporters that hydrolyze ATP and use the energy released from ATP hydrolysis to transport ions across biological membranes leading to the translocation of net charge across the membrane.

For example, the Na+/K+ ATPase (sodium pump) is an electrogenic pump because during every transport cycle, it transports 3 Na+ ions out of the cell and 2 K+ ions into the cell. This leads to the movement of one net positive charge out of the cell making this process electrogenic.

Related glossary terms/phrases:
Electrogenic



Definition:
Neurotoxins are chemical molecules that have an adverse effect on neuron function and, thus, disrupt the normal function of the nervous system. Neurotoxins could be small molecules or peptides and can be derived from a variety of invertebrate and vertebrate animals, as well as plant species.

The following is a short list of some examples of neurotoxins:

α-Bungarotoxin: A peptide neurotoxin that inhibits the nicotinic acetylcholine receptor.

Chlorotoxin: A peptide neurotoxin that inhibits chloride channels.

α-Conotoxin: A peptide neurotoxin that inhibits the nicotinic acetylcholine receptor.

δ-Conotoxin: A peptide neurotoxin that inhibits voltage-gated sodium channels.

w-Conotoxin: A peptide neurotoxin that inhibits N-type voltage-gated calcium channels.

Picrotoxin: Inhibits GABAA receptor chloride channels.

Tetrodotoxin: Inhibitor of neuronal voltage-gated sodium channels.



Definition:
Ouabain binds to and inhibits the transport activity of the Na+/K+/ATPase (i.e., sodium pump).

Ouabain is plant derived and belongs to the class of drugs referred to as cardiac glycosides. Similar to other cardiac glycosides, ouabain increase heart muscle contractility. However, ouabain is used only experimentally and not in humans (as for example digoxin is for the treatment of congestive heart failure).

There is some evidence that ouabain may be produced endogenously in humans.

Related glossary terms/phrases:
Vanadate

Other resources:
Ouabain (Wikipedia)



Abbreviation:
TEA

Definition:
An inhibitor of voltage-gated potassium (K+) channels.

TEA is a quaternary ammonium cation (positively charged ion). It is also commonly used as a cation replacement for sodium (Na+) in physiological buffers used in ion replacement experiments.

See also:
Pharmacological Inhibition of Na+ and K+ Channels



Abbreviation:
TTX

Definition:
Inhibitor of fast voltage-gated sodium (Na+) channels of neurons and muscle cells. It is an extremely potent and toxic neurotoxin.

See also:
Pharmacological Inhibition of Na+ and K+ Channels

Other resources:
Tetrodotoxin (Wikipedia)



Definition:
An inhibitor of the Na+/K+/ATPase (i.e., sodium pump). The form commonly used for this purpose is sodium orthovanadate.

Related glossary terms/phrases:
Ouabain









Posted: Sunday, March 31, 2013
Last updated: Friday, August 28, 2015