Ion Channels
Ion channels allow the movement of ions across cell membranes, and are therefore fundamental to physiological processes such as muscle contraction and nerve communication. Ion channels are glycoproteins that tranverse the cell membrane, the subunits of which can be copies of the same protein or a combination of different proteins. These channels are selective for the types of ions they allow to cross depending on the electrochemical configuration of the protein subunits. It is common that a type of ion channel will allow several kinds of ions to cross, specially if they all share the same charge (positive or negative). The ions that are mostly carried in physiological conditions are free atoms in solution, typically sodium, potassium, calcium and chlorine. Since the physiological function of neurons is to carry information in the form of electrical impulses (action potential), ion channel function is determinant of brain function. But once an ion has entered or exited the cell, it not only changes its electrical membrane potential, but also several ions, particularly calcium, are used as messengers within the cell, and can regulate many complicated and long lasting effects of the cell's metabolism.
Many Physiological processes are dependant upon calcuim signals, and cell based cacluim flux assys are considered one of the most importanet techniques used in drug discovery. Find out how the IN Cell Analyzer as been used to measure calcium flux mediated through agonist activation of the M3 muscarinic receptor in live cells. | 
