Changes In Body Water Content Research Articles

Muscle Glycogen Assessment and Relationship with Body Hydration Status: A Narrative Review.

Muscle glycogen is a crucial energy source for exercise, and assessment of muscle glycogen storage contributes to the adequate manipulation of muscle glycogen levels in athletes before and after training and competition. Muscle biopsy is the traditional and gold standard method for measuring muscle glycogen; alternatively, 13C magnetic resonance spectroscopy (MRS) has been developed as a reliable and non-invasive method. Furthermore, outcomes of ultrasound and bioimpedance methods have been reported to change in association with muscle glycogen conditions. The physiological mechanisms underlying this activity are assumed to involve a change in water content bound to glycogen; however, the relationship between body water and stored muscle glycogen is inconclusive. In this review, we discuss currently available muscle glycogen assessment methods, focusing on 13C MRS. In addition, we consider the involvement of muscle glycogen in changes in body water content and discuss the feasibility of ultrasound and bioimpedance outcomes as indicators of muscle glycogen levels. In relation to changes in body water content associated with muscle glycogen, this review broadens the discussion on changes in body weight and body components other than body water, including fat, during carbohydrate loading. From these discussions, we highlight practical issues regarding muscle glycogen assessment and manipulation in the sports field.

The effects of resistance exercise on obstructive sleep apnea severity and body water content in older adults: A randomized controlled trial

Objectives/backgroundThe prevalence of obstructive sleep apnea (OSA) in people over 70 years can reach up to 95%. Aerobic or combined exercise programs have been shown to impact positively on OSA severity. Resistance training changes leg fluid retention. We hypothesized that through this mechanism it may have an impact on the OSA severity in older adults. Patients/methodsWe evaluated changes in the respiratory event index (REI) of older adults with moderate-severe obstructive sleep apnea in a randomized, masked, controlled, parallel group trial. Participants between the age of 65 and 80 years with REI between 20 and 50 events/hour were assigned randomly to 12 weeks of resistance training or healthy life-style recommendations. Change in REI was the primary outcome. Muscle thickness, maximum strength, and physical function were secondary outcomes and body mass index (BMI) and body water content were assessed as mediators. ResultsTwenty-three subjects were included, 57% men, aged 71 ± 5 years, randomized to training (n = 12) and control intervention (n = 11). The baseline REI in the training and control groups were 30 ± 7/h and 29 ± 9/h; at follow-up, the delta REI were −3.6/hour (95% confidence interval −0.7 to −5.4) and 6.7/hour (5.2–8.6), respectively, with significant time × group interaction that remained significant after adjusting the generalized estimating equations model for delta BMI and delta body water content. ConclusionsTwelve weeks of resistance training in older adults significantly changed the respiratory event index and was well tolerated. Changes in body water content were slight but cannot be dismissed as contributing to REI reduction.

Effect of furosemide on body composition and urinary proteins that mediate tubular sodium and sodium transport-A randomized controlled trial.

BackgroundFurosemide inhibits the sodium potassium chloride cotransporter (NKCC2) in the thick ascending limb of the loop of Henle and increases urinary water and sodium excretion. This study investigates the effect of furosemide on body composition estimated with multifrequency bioimpedance spectroscopy (BIS) technique and urinary proteins from NKCC2.MethodsThis study is a randomized, placebo‐controlled, crossover study where healthy subjects received either placebo or 40 mg furosemide on two separate occasions, where body composition with BIS, renal function, proteins from tubular proteins that mediate sodium and water transport, and plasma concentrations of vasoactive hormones were measured before and after intervention.ResultsWe observed an expected increased diuresis with a subsequent reduction in bodyweight of (−1.51 ± 0.36 kg, p < .001) and extracellular water (ECW; −1.14 ± 0.23 L, p < .001) after furosemide. We found a positive correlation between the decrease in ECW and a decrease in bodyweight and a negative correlation between the decrease in ECW and the increase in urinary output. Intracellular water (ICW) increased (0.47 ± 0.28 L, p < .001). Urinary excretion of NKCC2 increased after furosemide and the increase in NKCC2 correlated with an increase in urine output and a decrease in ECW.ConclusionWe found BIS can detect acute changes in body water content but the method may be limited to estimation of ECW. BIS demonstrated that furosemide increases ICW which might be explained by an extracellular sodium loss. Finally, urinary proteins from NKCC2 increases after furosemide with a good correlation with diuresis end the decrease in ECW.

Chronic exposure to soil salinity in terrestrial species: Does plasticity and underlying physiology differ among specialized ground-dwelling spiders?

In salt marshes, the alternation of low and high tides entails rapid shifts of submersion and aerial exposure for terrestrial communities. In these intertidal environments, terrestrial species have to deal with an osmotic loss in body water content and an increase in sodium chloride concentration when salt load increases. In salt marshes, spiders represent an abundant arthropod group, whose physiological ecology in response to variations of soil salinity must be further investigated. In this study, we compared the effect of salinity on the survival and physiology of three species of Lycosidae; two salt marsh species (Arctosa fulvolineata and Pardosa purbeckensis) and one forest species (P. saltans). Spiders were individually exposed at three salinity conditions (0‰, 35‰ and 70‰) and survival, changes in body water content, hemolymph ions (Na+, Ca2+, Mg2+, K+; ICP-MS technique) and metabolites (mainly amino acids, polyols, sugars; LC and GC techniques) were assessed. The survival of the forest species P. saltans was very quickly hampered at moderate and high salinities. In this spider, variations of hemolymph ions and metabolites revealed a quick loss of physiological homeostasis and a rapid salt-induced dehydration of the specimens. Conversely, high survival durations were measured in the two salt-marsh spiders, and more particularly in A. fulvolineata. In both P. purbeckensis and A. fulvolineata, the proportion of Na+, Ca2+, Mg2+, K+ remained constant at the three experimental conditions. Accumulation of hemolymph Na+ and amino acids (mainly glutamine and proline) demonstrated stronger osmoregulatory capacities in these salt-marsh resident spiders. To conclude, even if phylogenetically close (belonging to the same, monophyletic, family), we found different physiological capacities to cope with salt load among the three tested spider species. Nevertheless, physiological responses to salinity were highly consistent with the realized ecological niches of the spiders.

Segmental extracellular and intracellular water distribution and muscle glycogen after 72-h carbohydrate loading using spectroscopic techniques.

Body water content increases during carbohydrate loading because 2.7-4-g water binds each 1 g of glycogen. Bioelectrical impedance spectroscopy (BIS) allows separate assessment of extracellular and intracellular water (ECW and ICW, respectively) in the whole body and each body segment. However, BIS has not been shown to detect changes in body water induced by carbohydrate loading. Here, we aimed to investigate whether BIS had sufficient sensitivity to detect changes in body water content and to determine segmental water distribution after carbohydrate loading. Eight subjects consumed a high-carbohydrate diet containing 12 g carbohydrates·kg body mass(-1)·day(-1) for 72 h after glycogen depletion cycling exercise. Changes in muscle glycogen concentration were measured by (13)C-magnetic resonance spectroscopy, and total body water (TBW) was measured by the deuterium dilution technique (TBWD2O). ICW and ECW in the whole body (wrist-to-ankle) and in each body segment (arm, trunk, and leg) were assessed by BIS. Muscle glycogen concentration [72.7 ± 10.0 (SD) to 169.4 ± 55.9 mmol/kg wet wt, P < 0.001] and TBWD2O (39.3 ± 3.2 to 40.2 ± 3.0 kg, P < 0.05) increased significantly 72 h after exercise compared with baseline, respectively. Whole-body BIS showed significant increases in ICW (P < 0.05), but not in ECW. Segmental BIS showed significant increases in ICW in the legs (P < 0.05), but not in the arms or trunk. Our results suggest that increase in body water after carbohydrate loading can be detected by BIS and is caused by segment-specific increases in ICW.

Overwintering biology of the carob moth Apomyelois ceratoniae (Lepidoptera: Pyralidae)

The pomegranate fruit moth, Apomyelois ceratoniae (Zeller), is the most important pest of pomegranate orchards in Iran, where infestations lead to 20%–80% fruit loss. A. ceratoniae overwinters as larvae in several instars. The success in overwintering determines the fruit loss in the following season, thus overwintering physiology of A. ceratoniae could provide insights into population prediction. To this end, overwintering strategy and some seasonal physiological and biochemical changes were investigated in the field-collected larvae of A. ceratoniae. The lowest supercooling point was recorded in November (−14.6 ± 0.9 °C) and the highest in both October and March (−10.2 ± 0.9 °C). The median lethal temperature (LT50) of larvae was higher than supercooling point, suggesting that A. ceratoniae is chill-susceptible. Overwintering larvae had slightly higher concentrations of glycerol and sorbitol compared to summer larvae. There were no significant seasonal changes in body water content or hemolymph osmolality. Current winter temperatures in Iranian orchards are higher than the cold tolerance thresholds of A. ceratoniae, suggesting that overwintering mortality is not a key factor in determining A. ceratoniae populations.

Evidence of a maternal effect that protects against water stress in larvae of the American dog tick, Dermacentor variabilis (Acari: Ixodidae)

We report that the ability to absorb water vapor from the air in larvae of the American dog tick, Dermacentor variabilis, changes depending upon moisture conditions where the eggs develop. When development occurs at lower relative humidities, resultant larvae can replenish water stores, maintain water balance, and survive at relative humidities as low as 75–85% RH, a range that agrees with previously published values for the critical equilibrium humidity or CEH. In contrast, exposure to high relative humidity conditions during development elevates the CEH to 93–97% RH. These larvae can survive only at relative humidities that are close to saturation, as 93% RH is a dehydrating atmosphere. For these larvae, absorption at 97% RH can be prevented by blocking the mouthparts with wax, indicating that an upward shift has occurred in the moisture threshold where the active mechanism for water vapor absorption operates. Based on transfer experiments between low and high relative humidities, the CEH of larvae is determined by the relative humidity experienced by the mother rather than the moisture conditions encountered by eggs after they are laid. The fact that no changes in body water content, dehydration tolerance limit and water loss rate were observed implies that adjustments to the CEH conferred by the mother have the adaptive significance of enabling larvae to maintain water balance by limiting the range of hydrating atmospheres.

Influence of soil hydric parameters on the winter cold hardiness of a burrowing beetle, Leptinotarsa decemlineata (Say)

This investigation examined the influence of soil moisture and associated parameters on the cold hardiness of the Colorado potato beetle (Leptinotarsa decemlineata Say), a temperate-zone species that overwinters in terrestrial burrows. The body mass and water content of adult beetles kept in sand at 4 °C varied over a 16-week period of diapause according to the substratum's moisture content. Changes in body water content, in turn, influenced the crystallization temperature (range −3.3 to −18.4 °C; n = 417), indicating that environmental moisture indirectly determined supercooling capacity, a measure of physiological cold hardiness. Beetles held in dry sand readily tolerated a 24-h exposure to temperatures ranging from 0° to −5 °C, but those chilled in sand containing as little as 1.7% water (dry mass) had elevated mortality. Thus, burrowing in dry soils not only promotes supercooling via its effect on water balance, but may also inhibit inoculative freezing. Mortality of beetles exposed to −5 °C for 24 h was lower in substrates composed of sand, clay and/or peat (36–52%) than in pure silica sand (78%) having an identical water content (17.0% dry mass). In addition to moisture, the texture, structure, water potential, and other physico-chemical attributes of soil may strongly influence the cold hardiness and overwintering survival of burrowing insects.

Dehydration tolerance in wood frogs: a new perspective on development of amphibian freeze tolerance.

Wood frogs, Rana sylvatica, tolerate the loss of 50-60% of total body water during experimental dehydration. The rate of water loss for unprotected frogs is the same whether animals are frozen (at -2 degrees C) or unfrozen (at 1 degrees C) but is greatly reduced when frogs are frozen under a protective layer of moss. Dehydrational death could occur in as little as 7-9 days for unprotected animals; this indicates the importance for winter survival of selecting well-protected and damp hibernation sites. Prior dehydration affected the cooling and freezing properties of frogs, reducing supercooling point and the amount of ice formed after 24 h at -2 degrees C and acting synergistically with freezing exposure in stimulating cryoprotectant synthesis. Analysis of the effects of controlled dehydration at 5 degrees C showed that changes in body water content alone (without freezing) stimulated liver glycogenolysis and the export of high concentrations of glucose into blood and other organs. Autumn-collected frogs dehydrated to 50% of total body water lost showed glucose levels of 165-1,409 nmol/mg protein in different organs, increases of 9- to 313-fold compared with control values and reaching final levels very similar to those induced by freezing exposure. The data support the proposal that various adaptations for natural freeze tolerance may have been derived from preexisting mechanisms for dealing with water stress in amphibians and that cell volume change may be one of the signals involved in triggering and sustaining molecular adaptations (e.g., cryoprotectant output) that support freezing survival.

Body Water Content and Distribution in Nonpregnant Adult Female Baboons

Water contents of the various body water compartments were estimated in 16 nonpregnant adult female baboons and compared to human data. Total body water, extracellular water, and plasma volumes were determined by dilution studies. Intracellular water, interstitial water, blood volume, and red cell volume were calculated. The data were compatible with the finding that baboon females probably have less body fat than their human counterparts. Our data establish a basis for longitudinal studies of the changes in body water content and distribution during normal and pathological pregnancies.

Regulation of body mass in rats exposed to chronic acceleration.

Female rats approximately 6 mo old were chronically centrifuged for up to 30 days at 2.76 G or 3.18 G and sacrificed at intervals for body-composition study. Both fat and the fat-free body mass (FFBM) were reduced during the 1st wk of centrifugation, with the fat showing considerably more variation both within and between groups. The FFBM was reduced below control level to the same extent in rats fed commercial chow, a high-fat diet, or a high-protein diet or in rats prefasted to produce a body-mass deficit at the start of centrifugation. There were no centrifugation-associated changes in body water content. It was concluded that body fat showed no evidence of regulation, FFBM is regulated at any constant level of acceleration between 1 and 4.15 G, and the change in FFBM induced by a change in acceleration is probably not regulated.

Growth and respiration throughout the life-cycle of Nematospiroides dubius Baylis, 1926 (Nematoda: Heligmosomidae). The free-living stages.

The growth of the three free-living stages ofN. dubiuswas measured in terms of dry and fresh weight. Changes in body water content during moulting were demonstrated by variations in dry weight when expressed as a percentage of fresh weight. The respiration rate of the larvae increased until they became infective, after which time it decreased until five days later no oxygen consumption could be recorded. The inability of all larval stages to withstand anaerobic conditions indicated that their metabolism was essentially aerobic. The relationship between body size and metabolic rate was established for each stage and its significance in relation to the life-cycle discussed.