Effect of Diamox (Acetazoleamide) on the Carbon Dioxide Tension of the Urine

Capeci, Nicholas E.; Kruesi, Oscar R.; Weaver, Davis C.; Hilton, James G.

doi:10.1152/ajplegacy.1957.191.1.55

Cited by 4 publications

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“…The source of the H2C0B (subsequently dehydrated to CO2 and H20) is most logically attributed to the secretion of H+ into luminal fluid containing HCO3-. 3. Marked increases in urine buffer excretion following phosphate infusions increased U-P gradients moderately, supporting the hypothesis that buffer can influence urinary CO2 tension by delaying the dehydration of H2CO3.…”

Section: Methodsmentioning

confidence: 54%

“…Evidence has recently been presented (3) to support the thesis that the high CO2 tension in urine during a bicarbonate diuresis induced by Diamox® is the consequence, not of the enhanced bicarbonate excretion, but of the buffering action of the inhibitor.…”

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confidence: 96%

“…Pitts and Alexander (1) proposed that the CO2 tension in alkaline urines is increased as a result of the following sequence: 1) increased delivery of NaHCO3 to the distal tubule; 2) increased formation of HCO3 as a result of a Na+-H+ exchange in this segment; 3) delayed dehydration of the H2CO0 thus formed. More recently, Kennedy, Eden and Berliner (2) have emphasized the role of nonbicarbonate buffer as the factor responsible for delayed dehydration of H2C03.…”

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confidence: 99%

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The Relation of Urinary Co2 Tension to Bicarbonate Excretion*

Portwood¹,

Seldin²,

Rector³

et al. 1959

J. Clin. Invest.

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The mechanism whereby high CO2 tensions are formed in the urine has been the subject of considerable debate. Pitts and Alexander (1) proposed that the CO2 tension in alkaline urines is increased as a result of the following sequence: 1) increased delivery of NaHCO3 to the distal tubule; 2) increased formation of HCO3 as a result of a Na+-H+ exchange in this segment; 3) MATERIALS AND METHODSA total of 27 experiments were performed on normal young adults (medical students, house officers and student nurses) after an overnight fast.Maximum water diuresis was maintained by the rapid intravenous infusion of either 5 per cent dextrose or 5 per cent fructose in water. The subjects remained recumbent throughout the experiments except for those individuals from whom voided urine specimens were obtained. Urine collection periods of 15 to 20 minutes were employed; the samples were collected under mineral oil by direct voiding in some experiments, by indwelling catheter in most. At the mid-point of each urine collection period blood was drawn into heparinized, oiled syringes from an indwelling needle in either a brachial or femoral artery.Blood and urine pH were anaerobically determined immediately with a Cambridge pH meter with the electrode assembly housed in an incubator at a constant temperature of 370 C. Plasma and urine CO2 content were determined by the method of Van Slyke and Neill (4). Bicarbonate concentration and pCO2 were calculated from the Henderson-Hasselbalch equation. The pK, of H2C08 in urine was estimated for each sample according to the formula: pK, = 6.33 -0.5 -1B, where B represents the total cation concentration of the sample in question (5).It was assumed that the sum [Na+]+ [K+] was equal to at least 95 per cent of [B+]. It was found that the arbitrary selection of a pK1 of 6.10 introduced a variable error of considerable magnitude when calculating pCO2 in urines of varying pH and bicarbonate concentration.However, using the pK, estimated from 6.33 -0.5 -/B, close agreement was obtained between calculated pCO2 and tonometrically determined pCO2. The conventional proportionality constant of 0.0309 was used to convert[H2COJ] to pCO2. For plasma, a pK1 of 6.10 and a proportionality constant of 0.0301 were used.Inorganic phosphate in urine was determined by the method of Fiske and Subbarow (6). Titration curves for urines obtained during several of the experiments were determined as follows:Ten ml. urine was acidified to < pH 2.0 by the addition of 0.1 HCl. Following vigorous stirring for 15 minutes (to dispel generated CO2), the samples were titrated to pH 6.0 to 6.2 with 0.1 N NaOH. Further titration to pH > 8.0 was performed with 0.01 N NaOH which was 770

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Section: Methodsmentioning

confidence: 54%

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confidence: 96%

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confidence: 99%

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