High altitude-induced albuminuria in normal man is enhanced by infusion of low-dose dopamine

Abstract

Renal function and the urinary excretion rate of albumin (U_alb) at rest and during infusion of dopamine (3 μg kg⁻¹ min⁻¹) were investigated in eight normal volunteers at sea level and 48 h after a rapid, passive ascent to an altitude of 4350 m. Oxygen saturation decreased to 81% (77—85) (median with quartiles in parentheses) at high altitude. High altitude hypoxia increased U_alb from 3.2 μg min⁻¹ (2.7—3.5) to 5.0 μg min⁻¹ (3.3—6.6) (p<0.05); increased mean arterial blood pressure from 80 mmHg (73—95) to 102 mmHg (96—108) (p<0.01); decreased the effective renal plasma flow (ERPF) from 465 ml min⁻¹ (412—503) to 410 ml min-¹ (385—451) (p<0.05), and increased the filtration fraction from 24% (22—27) to 28% (26—29) (p<0.01). Glomerular filtration rate (GFR), and the renal clearances of lithium (C_Li) and sodium (C_Na) remained unchanged at high altitude. Dopamine increased ERPF, GFR, C_Li, C_Na, and decreased the filtration fraction in both environments. Infusion of dopamine further increased U_alb to 10.5 μg min⁻¹ (5.5—64.8) (p<0.05) at high altitude, but had no effect on U_alb at sea level. In conclusion, high altitude hypoxia per se increases the urinary excretion rate of albumin, which is further increased by the renal vasodilating drug dopamine. This effect of dopamine at high altitude may result from combined effects of the increase in renal plasma flow and a hypoxia-induced increase in the glomerular capillary permeability to albumin.

Key Words:

• dopamine
• high altitude
• hypoxia
• kidney function
• urinary excretion rate of albumin