Effect of extracellular fluid volume contraction on distal-nephron hydrogen ion secretion in vivo
Tam, S.C.; Goldstein, M.B.; Richardson, R.M.; Robson, W.L.; Stinebaugh, B.J.; Halperin, M.L.
Journal of Laboratory and Clinical Medicine 96(3): 442-449
1980
ISSN/ISBN: 0022-2143 PMID: 6772720 Document Number: 156651
Collecting-duct H+ secretion in vivo in dogs with ECF gradient in alkaline urine. ECF voluem contraction was produced by daily administration of 20 mg of furosemide for 5 days to dogs on a Cl--deficient diet. The diuretic was discontinued for at least 5 days prior to the study. After short-term partial Na, K and Cl replacements, the blood acid-base values were pH 7.46 .+-. 0.01, PCO2 42 .+-. 1 mm Hg, and bicarbonate 29 .+-. 1 mM. The U-B PCO2 gradient was 82 .+-. 4 mm Hg and the urine bicarbonate, 180 .+-. 8 mM. This steady state was observed for 90 min. The U-B PCO2 fell to 46 .+-. 3 mm Hg (urine bicarbonate 184 .+-. 9 mM) when the ECF volume was expanded by the infusion of 0.7 M sodium bicarbonate and to 23 .+-. 2 after amiloride administration. Dogs with ECF volume contraction and Cl- deficiency had a marked increase in collecting-duct H+ secretion in vivo as indicated by the greater value for the U-B PCO2 gradient corrected for urine bicarbonate concentration.