Accession Number : ADA185946

Title :   Polycythemia and Hydration Status: Effects on Blood Volume and Thermoregulation during Exercise-Heat Stress,

Corporate Author : BOSTON UNIV MA SCHOOL OF MEDICINE

Personal Author(s) : Sawka, Michael N ; Gonzalez, Richard R ; Young, Andrew J ; Muza, Stephen R ; Pandolf, Kent B

PDF Url : ADA185946

Report Date : Jul 1987

Pagination or Media Count : 30

Abstract : We studied the effects of autologous erythrocyte reinfusion on blood volume and thermoregulation during exercise in the heat. Five heat-acclimated males attempted four Heat Stress Tests (HSTs): two pre- and two post-reinfusion. Autologous erythrocyte reinfusion was accomplished with 500 ml of a NaC1-glucose-phosphate solution containing about 60% hematocrit. Both pre- and post-reinfusion on e HST was done while euhydrated and one HST was done while hypohydrated (-5% of body weight). After 30 min of rest in a 20 C antechamber, the HST consisted of a 120-min exposure (2 repeats of 15 min rest and 45 min walking) in a hot (35 deg C, 45%rh) environment. The following new findings were made concerning acute polycythemia in heat-acclimated subjects: (1) the increased erythrocyte volume was associated with a small plasma volume expansion; (2) the plasma volume expansion was associated with an increased total circulating protein mass; (3) the increased total circulating protein mass defends plasma volume when hypohydrated; (4) polycythemia increased sweating rate and reduced core temperature during exercise-heat stress; and (5) this thermoregulatory advantage conferred by acute polycythemia was effective even during hypohydration. Additionally, observations were made providing evidence that heat acclimation may increase extravascular protein mass.

Descriptors :   *BLOOD VOLUME, *ERYTHROCYTES, *HEAT STRESS(PHYSIOLOGY), *RATES, *HYDRATION, ACCLIMATIZATION, BLOOD DISEASES, BLOOD PLASMA, CIRCULATION, CORES, EXERCISE(PHYSIOLOGY), HEAT, MASS, PROTEINS, REDUCTION, TEMPERATURE, TEMPERATURE CONTROL, TEST METHODS, VOLUME, SWEAT COOLING, HEMATOCRIT, BODY TEMPERATURE, INFUSIONS

Subject Categories : Stress Physiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE