Renal function in experimental chronic hydronephrosis. V. Net acid excretion capacity in relation to renal pelvic volume after maximal loading with NH4Cl.

In 12 mongrel dogs intravenous loading with ammonium chloride (4 mmol NH4+/kg body weight) was performed before and 2-9 weeks after unilateral hydronephrosis had been produced by ligation of the ureter over an indwelling catheter. In an attempt to satisfy the demand for adequate, constant, alveolar ventilation a special respirator of the high-frequency positive-pressure ventilation (HFPPV) type was used. The acid-base status of the blood was determined before and after the loading and the acidification capacity of each kidney was assessed by measuring the amount of titratable acid and ammonium ions excreted in the urine. In the hydronephrotic kidney the excretion of both titratable acid and ammonium ions was statistically significantly reduced, both compared with the initial values in session I and compared with the healthy kidney in session II. After additional loading with ammonium chloride in session II, however, both kidneys increased their excretions to approximately similar extents. When the excretion was calculated per ml glomerular filtrate, no statistically significant changes were found between sessions I and II, either for the intact or the hydronephrotic kidney. The renal pelvic volume on the hydronephrotic side was measured and related to the reduction of the capacity of the kidney to excrete titratable acid and ammonium ions. No statistically significant correlation was obtained.