Renal K+ Channel Antibody Explorer Kit

The kidneys play a pivotal role in human physiology as they regulate heart and fluid homeostasis. They do so by regulating blood salt and mineral concentrations. This instrumental property of the kidneys is mediated by a small, yet very sophisticated functional unit, namely the nephron that filters unnecessary blood solutes into the urine while all necessary ions are carefully retained into the blood circulation. This "in and out" transition of ions across the vasculature is mediated by a battery of transmembrane protein-channels that facilitates the passage of solutes into and out of the blood circulation.

In the kidneys, potassium ions maintain a negative electric potential across the basolateral membrane and consequently, provide the driving force to transport other blood salts such as sodium across the membrane. Different potassium channels exist along the basolateral membrane of the tubule. The KCNK (K_2P) family are four transmembrane proteins, which control the resting negative membrane potential. KCNK12 (THIK-2) for example is ubiquitously expressed along different segments of the renal tubule and mediates potassium secretion into the extracellular space, and therefore facilitates sodium absorption¹.

The KCNJ (K_ir) family of potassium channels is more diverse and encode proteins such as ATP or G-protein gated channels as well as the classical inward rectifying channels. KCNJ10 (K_ir4.1) is a member of the inward rectifying potassium channels and is expressed on the basolateral membrane of the distal convoluted tubule where together with KCNJ16 (K_ir5.1) they control membrane action potential by mediating potassium transfer³. KCNJ1 (K_ir1.1) is an ATP dependent potassium channel and is expressed predominantly on the apical side of the nephron¹. This channel is very important for potassium secretion and regulates sodium absorption. In contrast, KCNJ13 (K_ir7.1) is not responsive to ATP and mediates potassium efflux across the basolateral membrane.

Members of the voltage gated potassium channels such as the KCNQ1 are also distributed along the apical membrane of the proximal tubule and are thought to play a role in sodium absorption².