Na,K-ATPase
The Na,K-ATPase, which is commonly know as the "sodium-potassium pump" or, more colloquially, the "sodium pump", is the protein which ensures that the cells keep their resting potential, by pumping sodium out of cells and potassium inside cells. While mammalian cells spend the most of their "currency", ATP (adenosine triphoshate), for the building of protein (25 to 30%), the second most important expenditure is for pumping sodium out, and potassium in (generally between 19 and 28%).[1] In the brain, however, the percentage of the cell's "budget" devoted to the sodium-potassium pump averages 50 %, with grey matter requiring more, and white matter demanding less, than 50 %.[2]
Factors controlling the pump's function
Energy availability in cells is a strict determinant of the function of the sodium-potassium pump.
The level of oxidative stress in and out of cells also affects the efficiency of the pump, in a mechanism called redox modulation. In the case of this protein, oxidative stress causes a loss of function of the protein. Diseases associated with oxidative stress will frequently be accompanied by a ionic dysregulation that is due at least in part to a redox down-regulation of the sodium-potassium pump (although oxidative stress and mitochondrial energy production are intertwined).
References
- ↑ Rolfe DF, Brown GC (1997). "Cellular energy utilization and molecular origin of standard metabolic rate in mammals". Physiol. Rev. 77 (3): 731–58. PMID 9234964. [e]
- ↑ Attwell D, Laughlin SB (2001). "An energy budget for signaling in the grey matter of the brain". J. Cereb. Blood Flow Metab. 21 (10): 1133–45. DOI:10.1097/00004647-200110000-00001. PMID 11598490. Research Blogging. see page 1142, left.