Amiloride prevents the metabolic acidosis of a KCl load in nephrectomized rats.
1. Counter movements of K+ and H+ across cell membranes were studied in nephrectomized KCl-loaded rats. In one group of animals, the movements of K+ and H+ were determined during and after a KCl load, and in another group, amiloride was used in order to evaluate Na+ participation in K+/H+ exchange. 2. After a KCl load at constant PCO2, 79% of infused K+ left the inulin space, half of which was in exchange for H+. As a result, blood pH fell from 7.40 +/- 0.01 to 7.30 +/- 0.01 (mean +/- SEM; P less than 0.001). 3. During KCl infusion, the K+/H+ exchange ratio varied between 1.3 and 6.8, showing that the coupling ratio is not fixed. 4. Amiloride did not change blood pH and plasma [K+], but prevented the metabolic acidosis produced by the KCl load without affecting K+ entry into the non-inulin space. Therefore, K+ and H+ movements became completely dissociated. 5. The results indicate that KCl activates an amiloride-sensitive H+ extrusion from the cells. This finding is compatible with the view that Na+/H+ exchange participates in the metabolic acidosis produced by a KCl load.
Altenberg
G A
GA
Instituto de Investigaciones Cardiológicas, Facultad de Medicina, Universidad de Buenos Aires, Argentina.
Aristimuño
P C
PC
Amorena
C E
CE
Taquini
A C
AC
D000138:Acidosis / Q000378:metabolism*; D000584:Amiloride / Q000494:pharmacology*; D000818:Animals; D006859:Hydrogen / Q000378:metabolism; D008297:Male; D009392:Nephrectomy; D011188:Potassium / Q000378:metabolism; D011189:Potassium Chloride / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000378:metabolism
D011189:Potassium Chloride; D000584:Amiloride; D006859:Hydrogen; D012964:Sodium; D011188:Potassium