Hormonal Regulation of Fluid and Electrolytes: Effects of Heat Exposure and Exercise in the Heat

Francesconi, Ralph P.; Sawka, Michael N.; Hubbard, Richard W.; Pandolf, Kent B.

doi:10.1007/978-1-4613-0585-9_2

Cited by 10 publications

(8 citation statements)

References 101 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Studies seeking to identify other biological indicators of hydration status have shown an increase in serum cortisol levels with dehydration. Achieving euhydration, in such cases, is associated with normalizing of the serum cortisol levels (Francesconi et al, 1989). The results of the aforemen- (Vedhara et al, 2000).…”

Section: Hormonal Theoriesmentioning

confidence: 97%

Impaired cognitive function and mental performance in mild dehydration

2003

View full text Add to dashboard Cite

Dehydration is a reliable predictor of impaired cognitive status. Objective data, using tests of cortical function, support the deterioration of mental performance in mildly dehydrated younger adults. Dehydration frequently results in delirium as a manifestation of cognitive dysfunction. Although, the occurrence of delirium suggests transient acute global cerebral dysfunction, cognitive impairment may not be completely reversible. Animal studies have identified neuronal mitochondrial damage and glutamate hypertransmission in dehydrated rats. Additional studies have identified an increase in cerebral nicotinamide adenine dinucleotide phosphate-diaphorase activity (nitric oxide synthase, NOS) with dehydration. Available evidence also implicates NOS as a neurotransmitter in long-term potentiation, rendering this a critical enzyme in facilitating learning and memory. With ageing, a reduction of NOS activity has been identified in the cortex and striatum of rats. The reduction of NOs synthase activity that occurs with ageing may blunt the rise that occurs with dehydration, and possibly interfere with memory processing and cognitive function. Dehydration has been shown to be a reliable predictor of increasing frailty, deteriorating mental performance and poor quality of life. Intervention models directed toward improving outcomes in dehydration must incorporate strategies to enhance prompt recognition of cognitive dysfunction.

show abstract

Section: Hormonal Theoriesmentioning

confidence: 97%

Impaired cognitive function and mental performance in mild dehydration

2003

View full text Add to dashboard Cite

show abstract

“…plasma arginine vasopressin, AVP, aldosterone and atrial natriuretic peptide, ANP; Francesconi et al 1989;Wade et al 1989;Zambraski 1990). Thus, because of the eects of these hormones on the kidney, such dehydrating events are accompanied by reduced urinary¯uid and electrolyte losses.…”

Section: Introductionmentioning

confidence: 99%

Comparison of passive heat or exercise-induced dehydration on renal water and electrolyte excretion: the hormonal involvement

Melin

Koulmann

Jimenez

et al. 2001

European Journal of Applied Physiology

View full text Add to dashboard Cite

The effects of hydromineral hormones and catecholamines on renal water and electrolyte excretion were examined during and after dehydration induced by either passive heat or exercise. Eight healthy young Caucasian subjects participated in three separate trials, each including three consecutive phases. Phases 1 and 3 involved a 90-min period at rest in a thermoneutral environment, while phase 2 involved a 120-min period designed to provide: (1) euhydration (control trial), (2) passive heat-induced dehydration of 2.8% body mass, or (3) exercise-induced dehydration of 2.8% body mass. During the two dehydration procedures, the decreases in urine flow and sodium excretion were more marked during exercise (P < 0.05). An increase in plasma catecholamines occurred only during exercise, together with a reduction in creatinine clearance and more marked increases in plasma renin and aldosterone than during passive heat exposure (P < 0.05). Although plasma vasopressin was elevated during the two dehydration procedures, urine osmolality did not change and, moreover, free water clearance increased during exercise (P < 0.05). Plasma levels of atrial natriuretic peptide increased markedly only during exercise compared to the other trials (P < 0.05). After the dehydration procedures, urine flow decreased again and urine osmolality increased markedly (P < 0.05), while plasma vasopressin remained elevated. These results suggest that sympathoadrenal activation during exercise plays a major role in the more marked reduction in diuresis and natriuresis than during passive heat exposure. Despite high plasma vasopressin concentrations during the two dehydrating events, the observed antidiuresis was not due to an increased renal concentrating ability, and the vasopressin was more effective after the dehydration procedures.

show abstract

“…These report decrements in a range of cognitive skills that become evident at around 2% body weight loss (Sharma et al, 1986;Gopinathan et al, 1988). However, these studies achieve dehydration by exposure to heat stress in combination with physical exercise, which make the cause of any impairment difficult to interpret (Francesconi et al, 1989;Kozlowski & Saltin, 1994). Furthermore, physical exercise may actually enhance cognitive performance (Hogervorst et al, 1996).…”

mentioning

confidence: 95%