A method to evaluate renal ammoniagenesis in vivo.
A reduced rate of excretion of ammonium (NH4+) can be due to either a low rate of production and/or a low transfer of NH4+ to the urine. At present, there is no way to obtain a measure of the rate of production of NH4+ in vivo without invasive techniques. Hence, our purpose was to develop a non-invasive test to reflect this rate in vivo. Conditions were selected so that there would be a wide range in the rate of production of NH4+ in the kidney. Initial experiments were performed in dogs because both the rate of production and excretion of NH4+ could be measured directly. The rate of excretion of NH4+ in normal dogs on their usual diet varied over a wide range and was not directly related to its rate of production. Nevertheless, 59% of the NH4+ produced was excreted when the pH of urine was < 6 or when the rate of flow of urine was high (after administering a loop diuretic). To produce a urine with a low pH and high flow rate in humans, a loop diuretic (20 mg of furosemide) and a mineralocorticoid (200 micrograms of fludrocortisone) were given. The pH of urine fell to 5.1 and the rate of urine flow rose to 8 ml/min; the rate of excretion of NH4+ rose from 21 to 33 mumol/min when the urine flow rate rose.(ABSTRACT TRUNCATED AT 250 WORDS)
Vasuvattakul
S
S
Renal Division, St. Michael's Hospital, Toronto, Ontario.
Gougoux
A
A
Halperin
M L
ML
D000328:Adult; D000641:Ammonia / Q000378:metabolism / Q000652:urine*; D000643:Ammonium Chloride / Q000008:administration & dosage; D000818:Animals; D004231:Diuresis / Q000502:physiology; D004285:Dogs; D005260:Female; D005665:Furosemide / Q000494:pharmacology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007668:Kidney / Q000378:metabolism*; D007674:Kidney Diseases / Q000175:diagnosis / Q000652:urine; D008297:Male; D014563:Urodynamics / Q000502:physiology
D000643:Ammonium Chloride; D000641:Ammonia; D005665:Furosemide