Changes in blood plasma during progressive dehydration

Senay, L. C.; Christensen, Margaret L.

doi:10.1152/jappl.1965.20.6.1136

Cited by 51 publications

(31 citation statements)

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“…Therefore, based on body weight or surface area, if a female loses water via sweat glands at the same rate as a male, her plasma osmolarity increases at a greater rate than that of the male, thus affecting her sweat rate (Senay, 1968). Indeed, in support of this position the plasma osmolarity of the four female subjects during dehydration increased approximately 1P5 % for each 1 % body weight loss (Table 2), while similarly exposed males exhibited a 1 1 % increase in plasma osmolarity for each 1 % body weight loss (Senay & Christensen, 1965).…”

Section: Resultsmentioning

confidence: 80%

“…Each subject behaved similarly in that the increase in To during post-ovulatory dehydration was much less than pre-ovulatory increments in To, Indeed, two subjects showed an ability to reduce their body temperatures even as weight loss was continuing. The intercepts of all the regression equations (b, (Adolph & Associates, 1947;Bass & Henschel, 1956;Senay & Christensen, 1965;Senay, 1972). The reason for this lack of plasma volume expansion in these female subjects is not directly revealed by the experimental results.…”

Section: Resultsmentioning

confidence: 95%

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Body fluids and temperature responses of heat‐exposed women before and after ovulation with and without rehydration

Senay¹

1973

The Journal of Physiology

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SUMMARY1. Four females (21-25 yr) were exposed to 43.30 C dry bulb, 28-29°C wet bulb, for 10 hr both early and late in two menstrual cycles. During the experiments in one cycle, the subjects were rehydrated while during the experiments in another cycle, the subjects were allowed to progressively dehydrate.2. Rates of weight loss and oral temperatures were determined hourly while venous blood samples were obtained before and then after 1, 2, 3, 4, 6, 8, and 10 hr of heat exposure.3. Pre-ovulatory results were compared with post-ovulatory results and dehydration experiments with rehydration experiments. In addition, the data on these female subjects were compared with those presented elsewhere for similarly treated male subjects. 4. When compared to males, these resting females did not significantly haemodilute when heat exposed. In addition, the female subjects apparently suffered a decrease in plasma volume and body water at a rate some tPS times that of similarly exposed males.5. In general, % change in total protein/unit volume of plasma for these female subjects was similar to previously published results for males. However, there were significant differences in the manner in which albumin and globulin fractions changed before and after ovulation.6. The rates of body weight loss for these subjects were similar to those determined for males. No difference was noted between pre-and postovulatory rates of weight loss. Dehydration significantly depressed the rates of weight loss during heat exposure.7. Stimulation of sweating (assessed as weight loss) appeared to require similar amounts of heat storage before and after ovulation though initial post-ovulatory temperatures were generally higher.9-2 8. Progressive dehydration of females before ovulation was accompanied by rates of increase in oral temperatures that were similar to those seen for similarly exposed males.9. When females progressively dehydrated after ovulation, there was no statistically significant correlation between temperature rise and weight loss as had been noted in pre-ovulatory experiments. In addition, for all subjects, the rise in body temperature with dehydration was less after than before ovulation. Two subjects showed an ability to decrease their body temperature in the face of continued dehydration.10. Based on these results, the differences in the responses of males and females to heat exposure were ascribed mainly to two causes: a, inherent differences such as skin surface: blood volume ratios, and b, the inability of females to maintain their vascular volume during heat exposure.

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Section: Resultsmentioning

confidence: 80%

Section: Resultsmentioning

confidence: 95%

Body fluids and temperature responses of heat‐exposed women before and after ovulation with and without rehydration

Senay¹

1973

The Journal of Physiology

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“…Dehydration is defined as net loss of body water resulting from decreased water intake or increased water loss. Dehydration leads to elevated osmolality of plasma and other extracellular fluids (21).…”

Section: Role Of the Osmotically Regulated Transcription Factor Nfat5mentioning

confidence: 99%

Secretion of von Willebrand factor by endothelial cells links sodium to hypercoagulability and thrombosis

Dmitrieva

Burg

2014

Proc. Natl. Acad. Sci. U.S.A.

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Hypercoagulability increases risk of thrombi that cause cardiovascular events. Here we identify plasma sodium concentration as a factor that modulates blood coagulability by affecting the production of von Willebrand factor (vWF), a key initiator of the clotting cascade. We find that elevation of salt over a range from the lower end of what is normal in blood to the level of severe hypernatremia reversibly increases vWF mRNA in endothelial cells in culture and the rate of vWF secretion from them. The high NaCl increases expression of tonicity-regulated transcription factor NFAT5 and its binding to promoter of vWF gene, suggesting involvement of hypertonic signaling in vWF up-regulation. To elevate NaCl in vivo, we modeled mild dehydration, subjecting mice to water restriction (WR) by feeding them with gel food containing 30% water. Such WR elevates blood sodium from 145.1 ± 0.5 to 150.2 ± 1.3 mmol/L and activates hypertonic signaling, evidenced from increased expression of NFAT5 in tissues. WR increases vWF mRNA in liver and lung and raises vWF protein in blood. Immunostaining of liver revealed increased production of vWF protein by endothelium and increased number of microthrombi inside capillaries. WR also increases blood level of D-dimer, indicative of ongoing coagulation and thrombolysis. Multivariate regression analysis of clinical data from the Atherosclerosis Risk in Communities Study demonstrated that serum sodium significantly contributes to prediction of plasma vWF and risk of stroke. The results indicate that elevation of extracellular sodium within the physiological range raises vWF sufficiently to increase coagulability and risk of thrombosis.blood clotting | HUVEC | osmotic stress

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“…2). Given these contrasting circumstances of circulatory commitment in Groups A and B plus previous results (Senay & Christensen, 1965 for resting men exposed to heat, the following paradox must be considered: when heat and exercise are combined as when Group B was subjected to 400 C (Fig. 2) (Fig.…”

Section: Experiments I First Tunnel Periodmentioning

confidence: 99%

Changes in plasma volume and protein content during exposures of working men to various temperatures before and after acclimitization to heat: separation of the roles of cutaneous and skeletal muscle circulation

Senay¹

1972

The Journal of Physiology

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SUMMARY1. Ten male subjects were trained in stair stepping for 2 weeks. Group A (six subjects) was thereupon sequentially exposed for 45 min to dry bulb temperatures of 20, 40 and 300 C, a vapour pressure of 10-11 mm Hg and a wind speed of 1 m/sec in a climate tunnel. While temperature changes were being effected the subjects rested in an antechamber. Group B (four subjects) was exposed to a sequence of 40, 20 and 300 C. Work rate was the same for all subjects, i.e. 216 kg m/min (-to an oxygen consumption of 0 9 1./min). Duplicate experiments were run on both groups of subjects before and after acclimatization to heat.2. Throughout, periodic samples of venous blood, water and protein movement into or out of the extravascular compartment was assessed during exercise periods wherein blood flow was increased to exercising muscles (Group A, 20°C) or to both exercising muscles and skin (Group B, 400 C; Groups A and B, 300 C.) 3. Mild exercise in a cool environment before and after acclimatization to heat was accompanied by expansion of the vascular volume and an increase in the amount of circulating protein.4. Mild exercise in a warm environment for 45 min was accompanied by haemoconcentration and loss of protein from the vascular volume before subjects were heat acclimatized. The results were reversed following heat acclimatization; i.e. exposure of Group B to 400 C and of Groups A and B to 300 C was accompanied by haemodilution and addition to (or maintenance of) plasma protein concentration.5. Effects of heat acclimatization on exposure of Group A to 400 C were also noted.6. The effects of heat acclimatization were ascribed to: (a) a change in permeability of cutaneous capillaries to large molecules, (b) an increased availability of translocatable protein within cutaneous interstitial spaces, and (c) a combination of both a and b. 7. Further, the results supported a previous suggestion that addition or loss of water and protein from the vascular volume is dependent on the ratio of cutaneous to muscle blood flow.

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Changes in blood plasma during progressive dehydration

Cited by 51 publications

References 0 publications

Body fluids and temperature responses of heat‐exposed women before and after ovulation with and without rehydration

Body fluids and temperature responses of heat‐exposed women before and after ovulation with and without rehydration

Secretion of von Willebrand factor by endothelial cells links sodium to hypercoagulability and thrombosis

Changes in plasma volume and protein content during exposures of working men to various temperatures before and after acclimitization to heat: separation of the roles of cutaneous and skeletal muscle circulation

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