15 g daily away from slimming down K + intake sustained to possess 20 days (20, 43). Current conclusions (talked about below) possess identified the clear presence of an enthusiastic enteric K + sensing apparatus one to initiates brand new renal secretory process upon K + admission towards the digestion. The fresh new distal convoluted tubule has been identified as a web page vital to possess K + homeostasis, in which it acts as an effective K + sensor capable of opening K + excretion independent away from mineralocorticoid craft.
Report on Renal K + Addressing
K + was easily filtered along the glomerulus then avidly reabsorbed by the latest fabswingers proximal tubule and you can heavy ascending limb of the kidney. K + reabsorption regarding proximal tubule is mainly from paracellular path and is within the crude ratio into level of Na + and you will liquid reabsorbed (Fig. 1). Regarding the dense rising limb, K + reabsorption happen of the each other transcellular and you can paracellular pathways. Transcellular movement are mediated by the Na + -K + -2Cl ? cotransporter located on the apical membrane layer. A component of K + one to gets in the cell back diffuses for the lumen from the ROMK (renal external medullary K + ) station, leading to the fresh generation regarding a beneficial lumen positive costs and this, consequently, drives a component of K + reabsorption through the paracellular pathway (Fig. 2). K + secretion begins inside the early distal convoluted tubule and you can increasingly expands from inside the magnitude to the cortical event duct. Mental means handle this new secretory element of K + handling (36).
Fig. step 1.A big element of filtered K + are reabsorbed of the proximal tubule primarily from the paracellular pathway driven from the solvent drag. This new change inside the lumen potential out-of negative to positive regarding later servings of the proximal tubule provides an extra driving force to possess K + reabsorption. With the basolateral skin, K + entryway toward intracellular space of the Na + -K + -ATPase exits coupled so you can Cl ? thru an excellent conductive pathway. An effective K + station towards the apical epidermis of the proximal tubule acts to help you balance out cellphone current given the depolarizing effectation of Na + -paired sugar and you will amino acid reabsorption.
Fig. dos.More filtered K + one to escapes reabsorption regarding proximal tubule are reabsorbed on the dense ascending limb because of the both trancellular and you may paracellular routes. The fresh trancellular pathway try a good example of supplementary energetic transport. Intracellular Na + are leftover reduced of the pastime of Na + -K + -ATPase. Luminal Na + comes into this new cellphone along with Cl ? and you will K + via the Na + -K + -Cl ? cotransporter. Enough of luminal K + to the cotransport step are ensured of the K + course in the intracellular place on the lumen through the apically found renal exterior medullary potassium (ROMK) route. That it recycling off K + causes age group out of an effective lumen-confident charge, providing the driving force to have the next component of K + reabsorption through the paracellular pathway. Intracellular K + may leave the fresh new basolateral membrane in cotransport that have Cl ? otherwise thanks to good conductive path. ClC-Kb, Cl ? channel.
Maxi-K + otherwise BK channels are the second form of route that can mediates K + hormonal lower than conditions out of enhanced move
Electrogenic hormonal from ROMK route ‘s the major K + secretory apparatus on the distal nephron. As well as exciting maxi-K + avenues, tubular disperse in addition to augments electrogenic K + hormonal because of the diluting luminal K + quantity and revitalizing Na + reabsorption through the epithelial Na + station (ENaC). That it stimulatory impact will be tracked so you can a beneficial mechanosensitive assets whereby shear fret escalates the unlock likelihood of the ENaC station (30).