Proteinuria after Gravitational Acceleration Tolerance Training

Lee, Young Joon; Yim, Sung Vin; Lee, Moo Hoon

Abstract

BACKGROUND
Fighter pilots are frequently exposed to high gravitational acceleration force acting along the body axis from the head to the feet (+GZ) and this gravitational force causes considerable strain on several organ systems, including cardiovascular system and kidneys. Proteinuria had been observed after +GZ stress but the characteristics of urinary protein and the mechanism of proteinuria are not closely investigated up to now.
METHODS
A total of 44 student pilots were exposed to +6GZ for 30 seconds using Human Centrifuge and urine samples were collected before and after +GZ load. The amount of urinary protein was measured quantitatively and semiquantitatively with chemistry and dipstick, and the protein components were analysed with electrophoresis.
RESULTS
After a total of 44 student pilots were exposed to +6GZ for 30 seconds without anti-G suit, 19 urine samples were positive in dipstick protein test and electrophoresis revealed that their major protein component was albumin. The amount of urinary protein excretion and urinary protein and creatinine ratios (UProt/UCr) were significantly increased to levels of 33.4+/-29.3 mg/dL and 0.239+/-0.203 in comparison with pre-G training levels of 8.8+/-4.3 mg/dL and 0.046+/-0.018, respectively. All 44 urine samples collected the next day of G training were negative in dipstick protein test and had protein levels of 6.8+/-3.0 mg/dL. Of 19 subjects showed proteinuria, 15 performed the same +GZ training again with anti-G suit and so only three urine samples were positive in dip stick protein test.
CONCLUSIONS
These results indicates that transient proteinuria can be developed after high +GZ stress most possibly due to increased glomerular permeability of albumin and be effectively protected by the anti-G suit.