Healthy humans increase ventilation and urinary output in response to acute hypoxia. The relationship between ventilatory and renal efficiency in response to hypoxia, however, has not being elucidated. In 8 healthy humans (33±4SE yrs) we studied ventilatory efficiency during exercise at sea level (SL) and urinary output in response to a water load at high altitude (HA)(5050 mt, CNR Pyramid Lab, Mt. Everest). Methods. At sea level (SL), each subject underwent two maximal incremental treadmill exercise test, on air (AIR) and on hypoxia (FiO2 0.12), with measurement of minute ventilation (V’E), oxygen uptake (V’O2), CO2 production (V’CO2) and heart rate (HR). At HA, two days after ascension, each subject underwent oral water loading (WL, 20 ml/Kg) followed by 3h measurements, in supine position, of urinary flow (UF) and volume (UV). Results (m±SE). At HA, mean WL was 1175±75 mL, total urinary excretion (UV TOT) was 1224±27 mL and WL/UV at 3h was 1.06±0.04. Peak UF (9.3±0.6 mL/min) and peak UV (551±33 mL) were observed 1h after WL, while WL/UV after 2h was 0.91±3.4. A significant correlation was found between WL/UV at 2h at HA and V’E/V’CO2 slope at SL during AIR (28.3±0.7; R2 = 0.84; P<0.01) and during FiO2 0.12 (32.1±0.8; R²= 0.75; P<0.01). Conclusions. The exercise ventilatory efficiency at SL, on air and on FiO2 0.12, predicts the ability of normal humans to excrete a water load at HA.
Exercise ventilatory efficiency at sea level (SL) predicts water load excretion at high altitude (HA)
POMIDORI, Luca;GENNARI, Alessandra;CAMPIGOTTO, FEDERICA;FARINATTI, Marco;COGO, Annaluisa;
2004
Abstract
Healthy humans increase ventilation and urinary output in response to acute hypoxia. The relationship between ventilatory and renal efficiency in response to hypoxia, however, has not being elucidated. In 8 healthy humans (33±4SE yrs) we studied ventilatory efficiency during exercise at sea level (SL) and urinary output in response to a water load at high altitude (HA)(5050 mt, CNR Pyramid Lab, Mt. Everest). Methods. At sea level (SL), each subject underwent two maximal incremental treadmill exercise test, on air (AIR) and on hypoxia (FiO2 0.12), with measurement of minute ventilation (V’E), oxygen uptake (V’O2), CO2 production (V’CO2) and heart rate (HR). At HA, two days after ascension, each subject underwent oral water loading (WL, 20 ml/Kg) followed by 3h measurements, in supine position, of urinary flow (UF) and volume (UV). Results (m±SE). At HA, mean WL was 1175±75 mL, total urinary excretion (UV TOT) was 1224±27 mL and WL/UV at 3h was 1.06±0.04. Peak UF (9.3±0.6 mL/min) and peak UV (551±33 mL) were observed 1h after WL, while WL/UV after 2h was 0.91±3.4. A significant correlation was found between WL/UV at 2h at HA and V’E/V’CO2 slope at SL during AIR (28.3±0.7; R2 = 0.84; P<0.01) and during FiO2 0.12 (32.1±0.8; R²= 0.75; P<0.01). Conclusions. The exercise ventilatory efficiency at SL, on air and on FiO2 0.12, predicts the ability of normal humans to excrete a water load at HA.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
