One of the most important parts of the cell is the cell membrane . Its mission, besides giving form to the cell, consists of separating it and protecting it from the external environment. In this way, the substances that want to enter inside must do so through transport mechanisms.
The most hydrophilic molecules, as is the case of ions, can not dissolve in the membrane itself, so they use the so-called ion channels to enter the cell. Among them we differentiate the ligand and voltage dependent channels, which include the sodium channels, the potassium channels and the chlorine channels.
What are ion channels?
The ion channels constitute a type of proteins that are immersed in the membrane of all the cells of the organism. When a certain stimulus reaches the cell, these proteins open and allow the entry or exit of ions through them.
It is a very fast type of transport that does not consume energy (passive transport).
This transfer of ions between the interior and the cellular exterior produces what we know as an electrochemical gradient, favoring the transmission of a large number of signals between some cells and others . Some of the functions that these channels allow are the following:
- Nervous and muscular excitation .
- Secretion of hormones
- Production and release of neurotransmitters.
- Cell proliferation
- Control of blood pressure.
- Multitude of cellular signaling pathways.
However, the external cell membranes are not the only ones in which these types of channels are found. Also important are the ionic currents generated in the inner membranes of numerous organelles such as lysosomes or mitochondria.
Structure of ion channels
Ionic channels are oligomeric proteins, that is, they are formed by several protein subunits. They usually consist of an alpha subunit, which forms the pore through which the ions are transported, and other beta subunits that are responsible for regulating the opening and closing of the pore.
Types of ion channels in the body
Ionic channels can be classified according to the stimulus that activates them. This allows us to differentiate between:
- Channels activated by voltage . Its opening is determined by the electrical potential that exists in the cells. They are generally responsible for transmitting electrical signals and action potentials . Inside this section is where the sodium, potassium and chlorine channels are located.
- Channels activated by ligand . In this case, what makes the channel open is the presence of some concrete molecule. This molecule, be it a hormone, a neurotransmitter or a drug, causes the opening or closing of the channel and the consequent activation of signaling pathways that will lead to different cellular responses.
- Other types of channels . Among them we have channels activated by intracellular mediators or channels activated by physical factors.
The chlorine channels
Chlorine channels are important in the regulation of various processes in the body. Some of them are cell excitability, substance transport and cellular pH regulation.
This type of channels are usually found in cell membranes but also in mitochondria and other intracellular organelles. The most important function of chlorine channels is that they are capable of causing cellular hyperpolarization , that is, they interrupt nerve impulses and give the cell time to stabilize.
In addition, red blood cells cause the release of bicarbonate and the entry of carbon dioxide, regulating its transport. There are some pathologies related to the alteration of this type of channels, among which .
Chlorine channels and benzodiazepines
There is a direct relationship between the ion channels of chlorine and the benzodiazepines. This group of drugs act on the receptors of an inhibitory neurotransmitter, GABA.
The mechanism of action of benzodiazepines is to enhance the response to GABA by facilitating the opening of the associated chlorine channels . In this way, the response to GABA increases proportionally and with it the inhibition of the central nervous system. This is how they achieve their anxiolytic and relaxing effect.
The channels of chlorine and alcohol
As for alcohol, its mechanism of action in this regard is similar to that of benzodiazepines despite the fact that it binds to a different place in the GABA receptor.
In this way, we have that alcohol potentiates the flow of chloride ions that induces GABA , increasing nervous inhibition. As more chlorine ions enter the cell, greater hyperpolarization and less excitability will occur. This translates into some of the characteristic effects of this substance in the body such as sedative or hypnotic effects.