The acid-base characteristics of two peritoneal dialysis solutions containing either lactate or acetate are compared and the time course of changes in intraperitoneal pH following instillation into the abdominal cavity is measured. The concentration of titratable acid (cTA) is 5.58 mmol/l or 7 times as high in solutions containing acetate as in those containing lactate (0.79 mmol/l). The buffer capacity, -dcTA/dpH, is 11.43 and 1.82 mmol/l, respectively. Following intraperitoneal instillation of 1.5 liter of the solutions, the time course is 2–3 times as long before intraperitoneal pH reaches 7 using acetate (18 min) as when using lactate (7 min). The above mentioned difference in acid-base characteristics as well as an individual acetate intolerance is supposed to be the cause for the development of abdominal pains and peritoneal irritation observed in some patients using acetate-containing solutions.123 mmol/l of sodium bicarbonate is to be added to the acetate solution to raise the pH value from 5.6 to 7.4. Neutralization using sodium bicarbonate will thus result in sodium intoxication of the patient. The use of lactate instead of acetate for peritoneal solutions is advocated.
Urinary acidification, bone metabolism and urinary excretion of calcium and citrate were evaluated in 10 recurrent stone formers with incomplete renal tubular acidosis (iRTA), 10 recurrent stone formers with normal urinary acidification (NUA) and 10 normal controls (NC). Patients with iRTA had lower plasma standard bicarbonate after fasting (P < 0.01) and lower urinary excretion of titratable acid (P < 0.05) and citrate (P < 0.01) compared with NUA patients and NC, and higher urinary excretion of ammonia (P < 0.05) compared with NC (P < 0.05). Hypercalciuria was found in 6 of 10 patients with iRTA compared with 3 of 10 with NUA, and 0 of 10 NC. The citrate/calcium ratio in urine was significantly reduced in iRTA compared with the value in NUA (P < 0.01), and in NUA compared with NC (P < 0.05). Biochemical markers of bone formation (serum osteocalcin) and bone resorption (urinary hydroxyproline) were significantly increased in iRTA compared with NUA and NC (P < 0.01), indicating increased bone turnover in stone formers with iRTA. Stone formers with iRTA thus presented with disturbed calcium, bone and citrate metabolism--the same metabolic abnormalities which characterize classic type 1 RTA. Mild non-carbonic acidosis during fasting may be a pathophysilogical factor of both nephrolithiasis and disturbed bone metabolism in stone formers with iRTA.
A low-cost technique for studies of mineral and net base balance in rodents is described. Metabolic units of plexiglass, modifiable according to special needs, were found to perform satisfactorily in short-term as well as in long-term studies. Young Wistar rats showed normal growth rate, and adult non-growing rats showed mineral and net base balances close to zero.
SummaryA method for the quantitative assessment of the balance of net acid (NAB) in growing infants with a changing body composition is described. Results of seventy measurements of the daily NAB in healthy growing premature infants ingesting modified cow's milk formulae are reported. The relative contributions of the various determinants of the daily net acid input in the infant differ from those in the normal adult, and growth appears to be associated with negative net acid balances due to base deposition in skeleton and new body water. The daily load of “undetermined anion” (UA) in the diet was found to be the largest single component of the NAB. Moreover, a strong correlation between the rates of dietary UA intake and fecal UA excretion suggested an active regulation of the transintestinal acid‐base balance. A model for such regulation, based upon available evidence concerning the transport of acid and base across the gastrointestinal membrane, is proposed and briefly discussed.
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