TY - JOUR

T1 - Albuminuria and overall capillary permeability of albumin in acute altitude hypoxia

AU - Hansen, J M

AU - Olsen, Niels Vidiendal

AU - Feldt-Rasmussen, B

AU - Kanstrup, I L

AU - Déchaux, M

AU - Dubray, C

AU - Richalet, J P

PY - 1994/5

Y1 - 1994/5

N2 - The mechanism of proteinuria at high altitude is unclear. Renal function and urinary excretion rate of albumin (Ualb) at rest and during submaximal exercise and transcapillary escape rate of 125I-labeled albumin (TERalb) were investigated in 12 normal volunteers at sea level and after rapid and passive ascent to 4,350 m. The calcium antagonist isradipine (5 mg/day; n = 6) or placebo (n = 6) was administered to abolish hypoxia-induced rises in blood pressure. Lithium clearance and urinary excretion of beta 2-microglobulin were used to evaluate renal tubular function. High altitude increased Ualb from 2.8 to > 5.0 micrograms/min in both groups (P <0.05). In the placebo group, high altitude significantly increased filtration fraction (P <0.05), but this response was abolished by isradipine. Lithium clearance and urinary excretion of beta 2-microglobulin remained unchanged by hypoxia in both groups. Exercise did not reveal any further renal dysfunction. In both groups, high altitude increased TERalb from 4.8 to > 6.7%/h (P <0.05). In conclusion, acute altitude hypoxia increases Ualb despite unchanged tubular function and independent of effects of isradipine on filtration fraction. The elevated TERalb suggests an overall increase in capillary permeability, including the glomerular endothelium, as the critical factor in high-altitude induced albuminuria.

AB - The mechanism of proteinuria at high altitude is unclear. Renal function and urinary excretion rate of albumin (Ualb) at rest and during submaximal exercise and transcapillary escape rate of 125I-labeled albumin (TERalb) were investigated in 12 normal volunteers at sea level and after rapid and passive ascent to 4,350 m. The calcium antagonist isradipine (5 mg/day; n = 6) or placebo (n = 6) was administered to abolish hypoxia-induced rises in blood pressure. Lithium clearance and urinary excretion of beta 2-microglobulin were used to evaluate renal tubular function. High altitude increased Ualb from 2.8 to > 5.0 micrograms/min in both groups (P <0.05). In the placebo group, high altitude significantly increased filtration fraction (P <0.05), but this response was abolished by isradipine. Lithium clearance and urinary excretion of beta 2-microglobulin remained unchanged by hypoxia in both groups. Exercise did not reveal any further renal dysfunction. In both groups, high altitude increased TERalb from 4.8 to > 6.7%/h (P <0.05). In conclusion, acute altitude hypoxia increases Ualb despite unchanged tubular function and independent of effects of isradipine on filtration fraction. The elevated TERalb suggests an overall increase in capillary permeability, including the glomerular endothelium, as the critical factor in high-altitude induced albuminuria.

KW - Adult

KW - Albumins

KW - Albuminuria

KW - Altitude Sickness

KW - Blood Pressure

KW - Capillary Permeability

KW - Diuresis

KW - Double-Blind Method

KW - Exercise

KW - Female

KW - Humans

KW - Isradipine

KW - Lithium

KW - Male

KW - Middle Aged

KW - Plasma Volume

KW - Renal Circulation

KW - Serum Albumin, Radio-Iodinated

KW - beta 2-Microglobulin

M3 - Journal article

C2 - 8063651

VL - 76

SP - 1922

EP - 1927

JO - Journal of Applied Physiology

JF - Journal of Applied Physiology

SN - 8750-7587

IS - 5

ER -