Of these NKCC1b is also known to be found in brain RNA (Gamba, 2005). It is noted here, though, that the two isoforms of the NKCC1 cotransporter is found only in the European eel (Anguilla anguilla) as per research of Cutler and Cramb, 2002. Nevertheless, there is ample evidence that NKCC1, in human and other mammalian species, is functionally implicated in CNS cells. It is observed by Gamba, 2005, that the NKCC1 cotransporter is activated by receptors and assists in neurotransmission by driving anions into the cell. It is also observed by Strange et al, 2000, that the work of the NKCC1 cotransporter complements that of the KCC2 one. The choice of the culture medium, the neuronal-specific CAD cell line, and the somewhat CNS-specific NKCC1 dovetails perfectly for a research attempt that seeks to establish new facts on the molecular identity and other expression patterns of these unique electroneutral cotransporters in cells of the central nervous system (CNS). G. Gamba's excellent 2005 review article on these cotransporters has been extensively used in this paper because it is the most comprehensive document prepared to date being inclusive of all aspects described so far.
The cation-coupled (Sodium and ...
The Cation-Coupled Cotransport System
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 need to transport ions and solutes in and out of the cells. Specific plasma membrane proteins mediate this transport system by either effecting sodium influx and potassium efflux with 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 utilises this gradient to move target ions across the membrane and thus this system is called a secondary 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).