Abstract
Although the neonatal kidney seems to he able to reabsorb HCO3− during respiratory acidosis. It is not clear whether renal bicarbonate tubular reabsorption (HCO3−TR) occurs in response to changes in blood pH, PaCO2 or plasma HCO3−. In an attempt to evaluate the relative importance of each of these factors, measurements of HCO3−TR, fractional excretion of HCO3− (FEHCO3−), glomerular filtration rate as endogenous creatinine clearance (Ccr) and urine flow (V) were done in 6 neonatal, anesthesized and mechanically ventilated pigs during four study periods: 1. Control, normal ventilation in room air (x pH 7.43, PaCO2 35, HCO3− 22); II. Respiratory alkalosis induced hy hyperventilation (x pH 7.62, PaCO2 22, HCO3− 24); III. Respiratory acidosls induced by adding 10% CO2 to inspired gas (x pH 7.12, PaCO2 71, HCO3−22); and IV. Hypercapnea with normal pH, which was ohtained hy infusion of NaHCO3 (x pH 7.38, PaCO2 74, HCO3− 48). Urine was collected anaerohically hy catheter. Results (x+SEM) were:
These data suggest: a) HCO3−TR is clearly influenced by HCO3− filtered load more than by PaCO2 or blood pH changes; b) significant increase in FEHCO3− in period IV, whom pH normalized and PaCO2 remained unchanged, indicates that pH exerts an important effect independent of PaCO2; and c) acute respiratory acidosis significantly affects urine flow Ccr.
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Thodenius, K., Zllleruelo, G., Suqulhara, C. et al. 1645 RENAL BICARBONATE HANDLING IN NEONATAL PIGS DURING NORMOXIC RESPIRATORY ACIDOSIS AND ALKALOSIS. Pediatr Res 19, 385 (1985). https://doi.org/10.1203/00006450-198504000-01669
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DOI: https://doi.org/10.1203/00006450-198504000-01669