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Hydration effects on vascular fluid dynamics during acute exposure to 3,048 m
Author(s) -
Castellani John William,
Muza Stephen R,
Kenefick Robert W,
Sawka Michael N
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.990.10
Subject(s) - morning , plasma osmolality , acute exposure , medicine , endocrinology , plasma volume , zoology , chemistry , biology , vasopressin
Vascular fluid dynamics [plasma volume (PV) and total circulating protein (TCP)] during acute (8‐h) high‐altitude (ALT) exposure are poorly described and the impact of hypohydration (HYPO) on these responses has not been reported. Seven men (25 ± 7 yr; 44.1 ± 4.9 ml/kg/min V0 2peak completed 4 experimental trials in a counterbalanced design. Subjects were sea level (SL) residents who had completed 4 days of heat acclimation prior to the trials. Trials were: a) SL‐Euhydrated (SL‐EUH); b) SL‐HYPO; c) ALT‐EUH; and d) ALT‐HYPO. The day before each trial, subjects completed a standardized exercise‐heat stress bout either with (EUH) or without (HYPO, −4% body mass) fluid replacement. Subjects maintained hydration status overnight and the following morning entered a hypobaric chamber (27°C) and rapidly ascended to either 150 m or 3,048 m (O 2 saturation = 89 ± 3 %). During each 8 h trial, subjects were sedentary except for completing a standardized submaximal exercise bout (60 min) between 1–2.5 h of exposure. Plasma osmolality was not altered by ALT but was increased (291 ± 5 to 300 ± 6 mosmol/kg) by HYPO. PV was not altered by ALT (3.37 ± 320 L) but was reduced (320 ± 120 ml, 9.5%, p<0.01) by HYPO. TCP (268 ± 30 g) was not altered by ALT or HYPO. These data indicate that vascular fluid dynamics are not altered during the initial 8h of exposure to 3,048 m regardless of hydration status. Not reflecting official views of the Army or DoD.