| Abstract: | The effects of prolonged hypoxia on body water distribution was studied in four unanesthetized adult goats (Capra lircus) at sea level and after 16 days in a hypobaric chamber [(380 Torr, 5,500 m, 24 +/- 1 degrees C); arterial PO2 = 27 +/- 2 (SE) Torr]. Total body water (TBW), extracellular fluid volume (ECF), and plasma volume (PV) were determined with 3H2O, [14C]inulin, and indocyanine green dye, respectively. Blood volume (BV) [BV = 100PV/(100 - hematocrit)], erythrocyte volume (RCV) (RCV = BV - PV), and intracellular fluid (ICF) (ICF = TBW - ECF) and interstitial fluid (ISF) (ISF = ECF - PV) volumes were calculated. Hypoxia resulted in increased pulmonary ventilation and arterial pH and decreased arterial PCO2 and PO2 (P less than 0.05). In addition, body mass (-7.1%), TBW (-9.1%), and ICF volume (-14.4%) all decreased, whereas ECF (+11.7%) and ISF (+27.7%) volumes increased (P less than 0.05). The decrease in TBW accounted for 89% of the loss of body mass. Although PV decreased significantly (-15.3%), BV was unchanged because of an offsetting increase in RCV (+39.5%; P less than 0.05). We conclude that, in adult goats, prolonged hypobaric hypoxia results in decreases in TBW volume, ICF volume, and PV, with concomitant increases in ECF and ISF volumes. |
