We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Effect of acute increases in filtered HCO<sub>3</sub><sup>-</sup> on renal hydrogen transporters: II. H<sup>+</sup>-ATPase.
- Authors
Maddox, David A.; Barnes, William D.; Gennari, F. John
- Abstract
Adaptive increases in renal bicarbonate reabsorption occur in response to acute increases in filtered bicarbonate (FLHCO3). In a previous study, we showed that an increase in FLHCO3 induced by plasma volume expansion increased the Vmax for Na+/H+ exchange activity in renal cortical brush border membrane vesicles (BBMV), providing a potential mechanism for the adaptive increase in HCO3- reabsorption. The present studies were undertaken to determine whether the increase in FLHCO3 induced by plasma expansion also stimulates the other major H+ transporter in cortical BBMV, the H+-ATPase. H+-ATPase activity was assessed in BBMV obtained from hydropenic and plasma expanded Munich-Wistar rats, using a NADH-linked ATPase assay. H+-ATPase activity was measured as the ouabain and oligomycin-insensitive, bafilomycin A1-sensitive component of total ATPase activity. Acute plasma expansion doubled single nephron FLHCO3, and this change was associated with a 64% increase in the Vmax for H+-ATPase activity, with no change in apparent Km. The Vmax for H+-ATPase activity correlated directly with whole kidney GFR and FLHCO3 (<em>r</em> = 0.68 and 0.72, respectively), and with single nephron GFR and FLHCO3 (<em>r</em> = 0.76 and 0.80, respectively). Thus, the mechanism for the adaptive increase in proximal tubular HCO3- reabsorption that occurs in response to acute increases in FLHCO3 appears to be related to increased activity of both H+-ATPase and Na+/H+ exchange in the apical membrane of the proximal tubule epithelium.
- Subjects
EPITHELIAL cells; CELL membranes; ADENOSINE triphosphatase; KIDNEY diseases; SODIUM compounds; EPITHELIUM
- Publication
Kidney International, 1997, Vol 52, Issue 2, p446
- ISSN
0085-2538
- Publication type
Article
- DOI
10.1038/ki.1997.351