Symptomatic Hyponatremia during Prolonged Exercise in Heat. (Reannouncement withNew Availability Information)

摘要

Although hyponatremia (HN) has been reported among endurance athletes, itsetiology often remains uncertain and of great interest to clinicians and physiologists. This case report presents physiologic evidence regarding the etiology and development of HN during exercise in the heat. A 21-yr-old male volunteer (K.G.) unexpectedly experienced symptomatic HN during a research investigation that involved controlled sodium (Na+) intake (137 mEq Na+.d(-1) for 7d) and exercise-heat acclimation (41 deg C; 30 min.h(-1),8 h.d(-1) for 10 d). Fluid balance, physiologic variables, and hematologic/hormone data were measured before and after the HN episode, with similar measurements recorded for nine unaffected volunteers. The results indicated: (1) HN was verified in K.G. plasma Na+ < 130 mEq.l(-1) after only 4 h of mild, intermittent exercise in heat; (2) K.G.'s heart rate, rectal temperature, blood pressure, and Na+ losses in sweat and urine were less than or equal control subjects at all times; (3) between hours 4-7, an inappropriately large release of vasopressin coincided with a decrease of urine volume to 0 ml.h(-1).... Sodium, Fluid-electrolyte balance, Aldosterone, RENIN, Arginine vasopressin, Plasma volume, Hyperhydration.