Sodium-hydrogen exchange system in LLC-PK1 epithelium
Abstract:
Sodium influx into LLC-PK1 cells has been characterized. The main amiloride-sensitive pathway for sodium entry through the apical membrane in this cell line is sodium-hydrogen exchange with an apparent Km for sodium of 19 mM. Influx is pH dependent and is amiloride sensitive with K1/2 of 30 microM. Inhibition of the sodium transport by protons (at 1 mM external sodium) is consistent with an interaction of H+ ions at a single site having an apparent pKH of 7.2. These data are similar to those reported previously for brush border membrane (BBM) isolated from kidney proximal tubule. However, in contrast to previously published reports, H+ does not compete with amiloride in blocking Na+ influx and exhibits a mixed inhibition with sodium ions. The latter, together with a direct and independent assessment of amiloride and sodium interaction, indicates that amiloride does not compete with sodium for the same site. Possible explanations for the discrepancy in the literature concerning the interaction of Na+, H+, and amiloride with the Na+-H+ exchanger and the characteristics of the Na+-H+ exchange system in LLC-PK1 are discussed.
More Related Videos
08:46Implementing Patch Clamp and Live Fluorescence Microscopy to Monitor Functional Properties of Freshly Isolated PKD Epithelium
Published on: September 1, 2015
06:43Functional Assessment of Intestinal Tight Junction Barrier and Ion Permeability in Native Tissue by Ussing Chamber Technique
Published on: May 26, 2021
Related Concept Videos
Transcellular Transport of Solutes
Renal Tubule and Collecting Duct
Proximal Convoluted Tubule (PCT):
The PCT is the initial segment of the renal tubule, extending from the Bowman's capsule that encloses the glomerulus. Its convoluted structure and microvilli-lined cells increase the surface area for reabsorption. The PCT reabsorbs glucose, amino acids, sodium, and water from the filtrate, ensuring essential...
Reabsorption and Secretion in the PCT
Transport mechanisms involving sodium ions (Na+) contribute significantly to solute reabsorption. These mechanisms include symport and antiport processes.
A key example is the...
Reabsorption and Secretion in the Loop of Henle
Reabsorption and Secretion in the DCT and Collecting Duct
The distal part of the DCT, along with the...
Physiology of the Genitourinary System II: Tubular Reabsorption and Secretion
