RT-PCR Analysis on Murine CAD Cells to Establish Molecular Identity of the KCC2 Cotransporter - Essay Example

The cation-coupled (Sodium and Potassium cations only) chloride cotransporters are a unique transmembranal transport system that is electrically neutral yet very effective in action (Gamba, 2005). These cotransporters constitute a secondary transcellular transport system that complements the primary cation transcellular transport system – the one mediated by the enzyme - -ATPase. In the primary system, the mover is an electrochemical gradient while in this chloride cotransporter system there is no such gradient, the reason why it has acquired the electroneutral label, and imbalances in chloride anion concentrations between intracellular and extracellular media constitute the prime mover of the system (Gamba, G., 2005). In absorptive and secretory epithelia there is a need to transport ions and solutes in and out of the cells.

Specific plasma membrane proteins mediate this transport system by either affecting sodium influx and potassium efflux with the accompaniment of those ions and/or solutes that need to be transported (Gamba, G., 2005). Except in choroidal plexus, these cations move through the epithelial basolateral membrane mediated by the action of the enzyme - -ATPase that creates an electrochemical gradient across the membrane. The plasma proteins mediate this transcellular transport that utilizes this gradient to move target ions across the membrane and thus this system is called a second one while the enzyme-mediated cation movement is called the primary system.

These two-component systems together constitute the primary ion transport system across cellular membranes in human physiology (Gamba, G., 2005).On the other hand, the cation-coupled cotransport system is considered a secondary one and a very important one at that. The cations - and - are coupled with the anions in a 1:1 stoichiometry that works electroneutrality. These electroneutral cation-coupled chloride cotransporters themselves constitute the primary movers of the system (Gamba, G., 2005).

Both epithelial and non-epithelial cells have this mechanism which has a net effect of chloride translocation across cell membranes.