Channel blocker

A channel blocker is the biological mechanism in which a particular molecule is used to to prevent the opening of ion channels in order to produce a physiological response in a cell. Channel blocking is conducted by different types of molecules, such as cations, anions, amino acids, and other chemicals. These blockers act as ion channel antagonists, preventing the response that is normally provided by the opening of the channel.

Ion channels permit the selective passage of ions through cell membranes by utilizing proteins that function as pores, which allow for the passage of electrical charge in and out of the cell. These ion channels are most often gated, meaning they require a specific stimulus to cause the channel to open and close. Certain channels called ligand-gated ion channels are mediated by the binding of a specific channel protein. Others, known as voltage-gated channels, open and close in response to a change in the membrane potential. Ultimately, both of these ion channel types regulate the flow of charged ions across the membrane and therefore mediate membrane potential of the cell.

Molecules that act as channel blockers are important in the field of pharmacology, as a large portion of drug design is the use of ion channel antagonists in regulating physiological response.

Main article: Ion channel

To comprehend the mechanism of channel blockers, it is critical to understand the composition of ion channels. Their main function is to contribute to the resting membrane potential of a cell via the flow of ions through a cell membrane. To accomplish this task, ions must be able to cross the hydrophobic region of a lipid bilayer membrane, an unfavorable process. To assist in ion transport, ion channels form a hydrophilic pore through the membrane which allows for the usually unfavorable transfer of hydrophilic molecules. Various ion channels have varying mechanism of function. They include:

Molecules that act as ion channel blockers can be used in relation to any of these various channels. For example, sodium channels, which are essential to the production of action potentials, are affected by many different toxins. Tetrodotoxin (TTX), a toxin found in pufferfish, completely blocks sodium ion transportation by blocking the selectivity filter region of the channel. Much of the structure of the pores of ion channels has been elucidated from studies that used toxins to inhibit channel function.

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