Alterations in Arginine Vasopressin with Exercise, Environmental Stress and Other Modifying Factors

Maresh, Carl M.; Judelson, Daniel A.

doi:10.1002/9780470757826.ch32

Cited by 1 publication

(1 citation statement)

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“…Plasma [Na ϩ ], Osm, and AVP responses. Prolonged exercise in the heat without Rehy increases plasma [AVP] (2,7,16). As plasma Osm has been identified as the primary mediator of AVP release (18), we hypothesized that infusion of the 0.9% IV saline infusion would raise the plasma [Na ϩ ] and plasma Osm above that of the 0.45% IV treatment, further stimulating AVP secretion in 0.9% IV treatment.…”

Section: Discussionmentioning

confidence: 99%

Rehydration with fluid of varying tonicities: effects on fluid regulatory hormones and exercise performance in the heat

Kenefick¹,

Maresh²,

Armstrong³

et al. 2007

Journal of Applied Physiology

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This study examined the effects of rehydration (Rehy) with fluids of varying tonicities and routes of administration after exercise-induced hypohydration on exercise performance, fluid regulatory hormone responses, and cardiovascular and thermoregulatory strain during subsequent exercise in the heat. On four occasions, eight men performed an exercise-dehydration protocol of approximately 185 min (33 degrees C) to establish a 4% reduction in body weight. Following dehydration, 2% of the fluid lost was replaced during the first 45 min of a 100-min rest period by one of three random Rehy treatments (0.9% saline intravenous; 0.45% saline intravenous; 0.45% saline oral) or no Rehy (no fluid) treatment. Subjects then stood for 20 min at 36 degrees C and then walked at 50% maximal oxygen consumption for 90 min. Subsequent to dehydration, plasma Na(+), osmolality, aldosterone, and arginine vasopressin concentrations were elevated (P < 0.05) in each trial, accompanied by a -4% hemoconcentration. Following Rehy, there were no differences (P > 0.05) in fluid volume restored, post-rehydration (Post-Rehy) body weight, or urine volume. Percent change in plasma volume was 5% above pre-Rehy values, and plasma Na(+), osmolality, and fluid regulatory hormones were lower compared with no fluid. During exercise, skin and core temperatures, heart rate, and exercise time were not different (P > 0.05) among the Rehy treatments. Plasma osmolality, Na(+), percent change in plasma volume, and fluid regulatory hormones responded similarly among all Rehy treatments. Neither a fluid of greater tonicity nor the route of administration resulted in a more rapid or greater fluid retention, nor did it enhance heat tolerance or diminish physiological strain during subsequent exercise in the heat.

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Section: Discussionmentioning

confidence: 99%