Na-K-2Cl cotransporter

solute carrier family 12 (sodium / potassium / chloride transporters), member 1
Properties of human protein
Identifier
Gene name	SLC12A1, NKCC2
External IDs	OMIM : 600840 ; UniProt : P55011 ;

solute carrier family 12 (sodium / potassium / chloride transporters), member 2
Properties of human protein
Identifier
Gene name	SLC12A2, NKCC1
External IDs	OMIM : 600839 ; UniProt : Q13621 ;

The Na-K-2Cl cotransporter is a protein that is used to absorb sodium , potassium and chloride . It is an electroneutral transport protein because, together with two positive ions , two negatively charged ions also enter the cell.

properties

There are two sub-forms, NKCC1 and NKCC2:

NKCC1 can occur in all cells of the body, but especially in the ducts of glands ; in the brain but only during embryogenesis . There, the effect of the neuronal reaction to γ-aminobutyric acid (GABA) and glycine changes from activating to inhibiting. This isoform is also involved in the endolymph production of the stria vascularis in the inner ear. NKCC1 sits basolaterally.

NKCC2, on the other hand, is restricted to the kidney . In the ascending part of Henle's loop , it serves to reabsorb the sodium and concentrate the urine. The potassium absorbed in this way can return to the lumen via the ROMK 1 channel . The chloride leaves the cell basolaterally just like the sodium. In the thick ascending part of the Henle loop, table salt is reabsorbed without water being able to follow, as this part of the loop is impermeable to water. This now leads to more water from the thin descending part of the loop of Henle getting into the interstitium and the urine to be concentrated. NKCC2 sits apically (towards the lumen).

Pathophysiology

If the NKCC2 in the Henle loop is defective, the so-called Bartter syndrome occurs , which is characterized by hypotension .

Drug blockade

One inhibitor of this transporter is furosemide , a loop diuretic. By blocking this transporter, the ions no longer reach the interstitium, so that there is no passive urine concentration. This leads to increased water excretion. This mechanism is used, among other things, to flush out edema in the case of heart failure or to lower blood pressure. A side effect can be a reversible hearing loss of more than 30–50 dB.

literature

Regulation of the inner milieu. In: Robert F. Schmidt, Florian Lang: Human Physiology. 29th edition. Springer Verlag, Berlin et al. 2005, ISBN 3-540-21882-3 , pp. 667ff.

Individual evidence

↑ VI Dzhala, DM Talos, DA Sdrulla, AC Brumback, GC Mathews, TA Benke, E. Delpire, FE Jensen, KJ Staley: NKCC1 transporter facilitates seizures in the developing brain . In: Nat. Med. Band 11 , no. 11 , November 2005, p. 1205-1213 , doi : 10.1038 / nm1301 , PMID 16227993 .
↑ Y. Ben-Ari, JL Gaiarsa, R. Tyzio, R. Khazipov: GABA: a pioneer transmitter that excites immature neurons and generates primitive oscillations . In: Physiol. Rev. Band 87 , no. 4 , October 2007, p. 1215-1284 , doi : 10.1152 / physrev.00017.2006 , PMID 17928584 .

[pmid16227993-1] VI Dzhala, DM Talos, DA Sdrulla, AC Brumback, GC Mathews, TA Benke, E. Delpire, FE Jensen, KJ Staley: NKCC1 transporter facilitates seizures in the developing brain . In: Nat. Med. Band 11 , no. 11 , November 2005, p. 1205-1213 , doi : 10.1038 / nm1301 , PMID 16227993 .

[pmid17928584-2] Y. Ben-Ari, JL Gaiarsa, R. Tyzio, R. Khazipov: GABA: a pioneer transmitter that excites immature neurons and generates primitive oscillations . In: Physiol. Rev. Band 87 , no. 4 , October 2007, p. 1215-1284 , doi : 10.1152 / physrev.00017.2006 , PMID 17928584 .