Effect Of Acute Hypertension On Renal Na+ Transporters Membrane Domain Localization

Acute hypertension (aBP) provokes a natriuresis/diuresis response associated with the retraction of NHE3 and NaPi2 from the proximal tubule microvilli (MV): NHE3 to the base of the MV and NaPi2 to endosomes. This study aimed to investigate whether this trafficking of Na + transporters and/or their regulators was associated with a redistribution between distinct membrane domains. After 15 min of aBP or paired sham procedure, renal cortex was fractionated on a sorbitol density gradient, and fractions were pooled into 3 windows (W1‐low density, W2 and W3‐high density), subjected to 1% Triton X‐100 extraction and spun down to separate detergent resistant (DR, pellet) from detergent soluble (DS, supernatant) proteins. In control W1 apical membranes the %DS NHE3 was lower than %DS NaPi2.The %DS of Na + transporter associated proteins NHERF‐1 and myosin VI was not significantly different across the density gradient. NHE3, NaPi2, NHERF‐1 and myosin VI redistributed from W1 to W2, 3 during aBP (previously shown). The %DS NHE3, NHERF‐1, Myosin VI, and megalin did not change with aBP but the %DS NaPi2 decreased significantly. In summary, there is no change in NHE3, nor NHERF‐1 or myosin VI, membrane domain properties as they move to the base of the MV during aBP, while NaPi2 redistributes to more ordered lipid domains consistent with trafficking to endosomes. DK34316