Autologous Red Blood Cell Reinfusion: Effects on Stress and Fluid Regulatory Hormones during Exercise-Heat Stress,
ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA
Pagination or Media Count:
This study assessed the effects of induced erythrocythemia on stress and fluid regulatory hormones during exercise in the heat. Six unacclimated male subjects received approximately 600 ml of a sterile saline solution containing 50 vv of autologous erythrocytes. Three heat stress tests HSTs were attempted one approximately 2 weeks prior to the reinfusion procedure, a second 48 h after the reinfusion procedure, and a third 1 wk later corresponding to 9 d subsequent to reinfusion. Each HST comprised three consecutive exercise and rest intervals of 4515 min, respectively VO2 approx. 2.0 Lmin, 1.56 ms, 6 incline, 35 C, 45 rh. Blood was withdrawn before the HST and 30 min into each exercise EX bout. In all 3 HSTs plasma cortisol PC levels were significantly p.01 reduced during the first exercise bout when compared to pre-exercise levels, and then progressively increased during the second and third exercise intervals during HST 1. During HST 2 48h post-infusion, however, PC levels were same blood samples from HST-1 pre-infusion. Plasma renin activity PRA and aldosterone ALD were significantly p.01 increased by the exerciseheat stress, but were unaffected by erythrocythemia either 48 h or 9 d subsequent to reinfusion. PRA and ALD were correlated r0.84, p.001 under all conditions. We concluded from this study that acutely induced erythropcythemia reduced the stress response to consecutive exerciseheat intervals as manifested in PC responses during HST 2.
- Medicine and Medical Research
- Stress Physiology