Effects of K+-deficient diets with and without NaCl supplementation on Na+, K+, and H2O transporters' abundance along the nephron

Dietary potassium (K+) restriction and hypokalemia have been reported to change the abundance of most renal Na+and K+transporters and aquaporin-2 isoform, but results have not been consistent. The aim of this study was to reexamine Na+, K+and H2O transporters' pool size regulation in response to removing K+from a diet containing 0.74% NaCl, as well as from a diet containing 2% NaCl (as found in American diets) to blunt reducing total diet electrolytes. Sprague-Dawley rats ( n = 5–6) were fed for 6 days with one of these diets: 2% KCl, 0.74% NaCl (2K1Na, control chow) compared with 0.03% KCl, 0.74% NaCl (0K1Na); or 2% KCl, 2%NaCl (2K2Na) compared with 0.03% KCl, 2% NaCl (0K2Na, Na+replete). In both 0K1Na and 0K2Na there were significant decreases in: 1) plasma [K+] (+excretion (+/H+exchanger isoform 3; Na+-K+-Cl−cotransporter; Na+-Cl−cotransporter, oxidative stress response kinase-1; renal outer medullary K+channel; autosomal recessive hypercholesterolemia; c-Src, aquaporin 2 isoform; or renin. Thus, despite profound hypokalemia and renal K+conservation, we did not confirm many of the changes that were previously reported. We predict that changes in transporter distribution and activity are likely more important for conserving K+than changes in total abundance.