TY - JOUR
T1 - Urine acid-base compensation at simulated moderate altitude
AU - Ge, Ri Li
AU - Babb, Tony G.
AU - Sivieri, Mark
AU - Resaland, Geir K.
AU - Karlsen, Trine
AU - Stray-Gundersen, Jim
AU - Levine, Benjamin D.
N1 - Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2006/3
Y1 - 2006/3
N2 - Acute exposure to high altitude elicits respiratory alkalosis, and this is partially corrected by renal compensation. To determine the time course and magnitude of renal compensation during short-term moderate altitude exposure, we measured urine gas tensions and acid-base status in 48 healthy men and women at four levels of simulated altitude exposures. Each subject was exposed in pseudorandom order to simulated altitudes of 1780, 2085, 2455, and 2800 m. in a decompression chamber for 24 h, separated by 1 week at sea level. Fresh urine was collected anaerobically at sea level and after 6 and 24 h of each altitude exposure. Urine pH increased significantly (p < 0.01) after 6 h at all altitudes and returned to baseline values by 24 h at the lowest altitudes. In contrast, urine pH remained elevated at the highest altitudes. The mean value of urine HCO3- at sea level was 1.67 ± 0.25 mmol/L, increased significantly after 6 h at all altitudes, and then returned to near baseline after 24 h at three lower altitudes (1780, 2085, and 2455 m). However, it remained elevated at 2800 m. PCO2 in urine was significantly increased after 6 h and returned to baseline after 24 h at all altitudes. These results suggest that (1) short-term low to moderate altitude exposure results in a marked HCO3- diuresis, which may be caused by inhibition of the secretion of renal tubular H+, and (2) renal HCO3- compensation was completed by 24 h at low to moderate altitude, but still incomplete at higher altitude.
AB - Acute exposure to high altitude elicits respiratory alkalosis, and this is partially corrected by renal compensation. To determine the time course and magnitude of renal compensation during short-term moderate altitude exposure, we measured urine gas tensions and acid-base status in 48 healthy men and women at four levels of simulated altitude exposures. Each subject was exposed in pseudorandom order to simulated altitudes of 1780, 2085, 2455, and 2800 m. in a decompression chamber for 24 h, separated by 1 week at sea level. Fresh urine was collected anaerobically at sea level and after 6 and 24 h of each altitude exposure. Urine pH increased significantly (p < 0.01) after 6 h at all altitudes and returned to baseline values by 24 h at the lowest altitudes. In contrast, urine pH remained elevated at the highest altitudes. The mean value of urine HCO3- at sea level was 1.67 ± 0.25 mmol/L, increased significantly after 6 h at all altitudes, and then returned to near baseline after 24 h at three lower altitudes (1780, 2085, and 2455 m). However, it remained elevated at 2800 m. PCO2 in urine was significantly increased after 6 h and returned to baseline after 24 h at all altitudes. These results suggest that (1) short-term low to moderate altitude exposure results in a marked HCO3- diuresis, which may be caused by inhibition of the secretion of renal tubular H+, and (2) renal HCO3- compensation was completed by 24 h at low to moderate altitude, but still incomplete at higher altitude.
KW - Acclimatization
KW - Decompression chamber
KW - High altitude
KW - Renal HCO
KW - Sa
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U2 - 10.1089/ham.2006.7.64
DO - 10.1089/ham.2006.7.64
M3 - Article
C2 - 16544968
AN - SCOPUS:33645650319
SN - 1527-0297
VL - 7
SP - 64
EP - 71
JO - High Altitude Medicine and Biology
JF - High Altitude Medicine and Biology
IS - 1
ER -