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At least 1,747 records · Page 97Linked to original sources
PubMed1986

Fluid balance during food deprivation and after intraruminal loads of water or isotonic saline in lactating and anoestral goats.

A study was made of water and salt balance during a 28 h period of starvation in lactating and anoestral goats. Food deprivation caused diminished water intake in all but one animal, and the secretion of urine and milk gradually decreased. The plasma volume and the glomerular filtration rate were reduced, the plasma Na concentration lowered, and the plasma renin activity and plasma aldosterone concentration raised during starvation. After 28 h without food the goats were given a load of water or saline into the rumen. The fall in the plasma protein concentration that occurred indicates that the plasma volume increased in all animals within 4 h of receiving saline, but was unchanged after the water load. The plasma Na concentration decreased further after the water load, but increased in all animals after the saline load. The plasma renin activity and plasma aldosterone concentration remained elevated after the intraruminal water load, but fell towards basic values after the saline load. The renal Na excretion decreased during food deprivation, and showed no increase within 4 h of saline loading. It appears that only the load of saline restored the salt and water homoeostasis of the animal. Lactating and anoestral goats do not apparently differ in their response to starvation. The effects of starvation on fluid balance seem to become as severe in goats as in monogastric species despite food reservoirs in the reticulo-rumen and omasum at the onset of food deprivation.

Animals↗
PubMed1999

Pericardial fluid absorption into lymphatic vessels in sheep.

We estimated the volumetric lymphatic clearance rate of pericardial fluid in sheep. In the first group of studies, 125I-human serum albumin (HSA) was injected into the pericardial cavity and after 4 h, various lymph nodes and tissues were excised and counted for radioactivity. Several lymphatic drainage pathways existed defined by elevated 125I-HSA in the middle and caudal mediastinal, intercostal, and the cardiac nodes located near the root of the aorta. In a second group of experiments, the plasma recovery of intrapericardially administered tracer was compared in sheep with intact lymphatics and in animals in which thoracic duct lymph was diverted and other relevant lymphatics ligated. The 4-h plasma recoveries were reduced significantly from an average of 12.2 +/- 3. 4% injected dose in the lymph-intact group to 3.0 +/- 1.1% injected dose in the diverted/ligated group (an inhibition of approximately 75%). In order to estimate the volumetric clearance of pericardial fluid through lymphatics in conscious sheep, 125I-HSA was administered into the pericardial cavity to serve as the lymph flow marker. 131I-HSA was injected intravenously to permit calculation of plasma tracer loss and tracer recirculation into lymphatics. From mass balance equations, total pericardial clearance into lymphatics averaged 1.50 +/- 0.43 ml/h or approximately 1.13 ml/h if one was to assume that the average 25% recovered plasma tracer in lymph diverted/ligated animals was due to nonlymphatic transport. In conclusion, mediastinal lymphatic pathways remove a volume equivalent to the pericardial volume (8.1 +/- 1.1 ml) every 5.4 to 7. 2 h.

Absorption↗
PubMed2000

Total antioxidant capacity as a tool to assess redox status: critical view and experimental data.

The measure of antioxidant capacity (AC) considers the cumulative action of all the antioxidants present in plasma and body fluids, thus providing an integrated parameter rather than the simple sum of measurable antioxidants. The capacity of known and unknown antioxidants and their synergistic interaction is therefore assessed, thus giving an insight into the delicate balance in vivo between oxidants and antioxidants. Measuring plasma AC may help in the evaluation of physiological, environmental, and nutritional factors of the redox status in humans. Determining plasma AC may help to identify conditions affecting oxidative status in vivo (e.g., exposure to reactive oxygen species and antioxidant supplementation). Moreover, changes in the plasma AC after supplementation with galenic antioxidants or with antioxidant-rich foods may provide information on the absorption and bioavailability of nutritional compounds. Consequently, this review discusses the rationale, interpretation, confounding factors, measurement limits, and human applications of the measure of plasma AC.

Antioxidants↗
PubMed2002

Rehydration after exercise with fresh young coconut water, carbohydrate-electrolyte beverage and plain water.

This is to cross-over study to assess the effectiveness of fresh young coconut water (CW), and carbohydrate-electrolyte beverage (CEB) compared with plain water (PW) for whole body rehydration and blood volume (BV) restoration during a 2 h rehydration period following exercise-induced dehydration. Eight healthy male volunteers (mean age and VO2max of 22.4 +/- 3.3 years and 45.8 +/- 1.5 ml min kg-1 respectively) exercised at 60% of VO2max in the heat (31.1 +/- 0.03 degrees C, 51.4 +/- 0.1% rh) until 2.78 +/- 0.06% (1.6 +/- 0.1 kg) of their body weight (BW) was lost. After exercise, the subjects sat for 2 h in a thermoneutral environment (22.5 +/- 0.1 degrees C; 67.0 +/- 1.0% rh) and drank a volume of PW, CW and CEB on different occasions representing 120% of the fluid loss. A blood and urine sample, and the body weight of each subject was taken before and after exercise and at 30 min intervals throughout a rehydration period. Each subject remained fasted throughout rehydration. Each fluid was consumed in three portions in separate trials representing 50% (781 +/- 47 ml), 40% (625 +/- 33 ml) and 30% (469 +/- 28 ml) of the 120% fluid loss at 0, 30 and 60 min of the 2 h rehydration period, respectively. The drinks given were randomised. In all the trials the subjects were somewhat hypohydrated (range 0.08-0.18 kg BW below euhydrated BW; p > 0.05) after a 2 h rehydration period since additional water and BW were lost as a result of urine formation, respiration, sweat and metabolism. The percent of body weight loss that was regained (used as index of percent rehydration) during CW, PW, and CEB trials was 75 +/- 5%, 73 +/- 5% and 80 +/- 4% respectively, but was not statistically different between trials. The rehydration index, which provided an indication of how much of what was actually ingested was used for body weight restoration, was again not different statistically between trials (1.56 +/- 0.14, 1.36 +/- 0.13 and 1.71 +/- 0.21 for CW, CEB and PW respectively). Although BV restoration was better with CW, it was not statistically different from CEB and PW. Cumulative urine output was similar in all trials. There were no difference at any time in serum Na+ and Cl-, serum osmolality, and net fluid balance between the three trials. Urine osmolality decreased after 1 h during the rehydration period and it was lowest in the PW trial. Plasma glucose concentrations were significantly higher compared with PW ingestion when CW and CEB were ingested during the rehydration period. CW was significantly sweeter, caused less nausea, fullness and no stomach upset and was also easier to consume in a larger amount compared with CEB and PW ingestion. In conclusion, ingestion of fresh young coconut water, a natural refreshing beverage, could be used for whole body rehydration after exercise.

Adult↗
PubMed1986

Canine renal responses to atrial stretch or intravenous saline are not attenuated at night.

Primates develop a diuresis and natriuresis in response to stimuli that increase central blood volume. However, the renal response is markedly attenuated when these same experimental stimuli are applied at night. The purpose of the present study was to determine whether a quadruped, specifically the dog, also demonstrates attenuated renal responses to similar stimuli given at night. Two experimental protocols were performed on conscious dogs at night: 1) left atrial distension by partial mitral valve obstruction and 2) intravenous saline administration. Results from these experiments were compared with results from comparable experiments performed on the same dogs during the day. Each experimental intervention produced increases in urine flow and sodium excretion and decreases in urine osmolality during both day and night experiments (all P less than 0.05). The responses obtained during the night did not differ significantly from those obtained during the day. Thus the dog does not demonstrate an attenuated renal response to central volume expansion during the night. This contrasts with the adaptive response in primates that serves to minimize fluid loss when the intrathoracic blood pool is increased during prolonged recumbency at night. Presumably quadrupeds, with trunks horizontal both day and night, do not require nocturnal adaptive mechanisms to conserve body fluids.

Animals↗
PubMed1999

Exercise in the heat: limitations to performance and the impact of fluid replacement strategies. Introduction to the symposium.

The cause of fatigue during prolonged exercise in the heat has not been clearly established, but performance appears to be limited by thermoregulatory and fluid balance factors. Both dehydration and hyperthermia separately impair performance. Prior acclimation reduces the impact of heat, and ingestion of fluids also improves performance. Ingested fluids should contain carbohydrate and some electrolytes, primarily sodium, but many factors will dictate the choice of fluids. These include the relative need for carbohydrate to supplement endogenous stores, the need for fluid replacement, the limitations on replacement imposed by the nature of the event, and the athlete's own requirements and preferences.

Acclimatization↗
PubMed1985

Epithelial water transport in a balanced gradient system.

The relationship between epithelial fluid transport, standing osmotic gradients, and standing hydrostatic pressure gradients has been investigated using a perturbation expansion of the governing equations. The assumptions used in the expansion are: (a) the volume of lateral intercellular space per unit volume of epithelium is small; (b) the membrane osmotic permeability is much larger than the solute permeability. We find that the rate of fluid reabsorption is set by the rate of active solute transport across lateral membranes. The fluid that crosses the lateral membranes and enters the intercellular cleft is driven longitudinally by small gradients in hydrostatic pressure. The small hydrostatic pressure in the intercellular space is capable of causing significant transmembrane fluid movement, however, the transmembrane effect is countered by the presence of a small standing osmotic gradient. Longitudinal hydrostatic and osmotic gradients balance such that their combined effect on transmembrane fluid flow is zero, whereas longitudinal flow is driven by the hydrostatic gradient. Because of this balance, standing gradients within intercellular clefts are effectively uncoupled from the rate of fluid reabsorption, which is driven by small, localized osmotic gradients within the cells. Water enters the cells across apical membranes and leaves across the lateral intercellular membranes. Fluid that enters the intercellular clefts can, in principle, exit either the basal end or be secreted from the apical end through tight junctions. Fluid flow through tight junctions is shown to depend on a dimensionless parameter, which scales the resistance to solute flow of the entire cleft relative to that of the junction. Estimates of the value of this parameter suggest that an electrically leaky epithelium may be effectively a tight epithelium in regard to fluid flow.

Animals↗
PubMed2004

Understanding the association between dietary antioxidants, redox status and disease: is the Total Antioxidant Capacity the right tool?

Total Antioxidant Capacity (TAC) considers the cumulative action of all the antioxidants present in plasma and body fluids, thus providing an integrated parameter rather than the simple sum of measurable antioxidants. The capacity of known and unknown antioxidants and their synergistic interaction is, therefore, assessed, thus giving an insight into the delicate balance in vivo between oxidants and antioxidants. There is new evidence indicating the importance of understanding the mechanisms of the homeostatic control of TAC in plasma and tissues and its modification during oxidative stress development. Recently, the epidemiological application of TAC has been proposed as a new tool for investigating the relationship between dietary antioxidants and cancer risk in population studies. This review outlines the pros and cons of the more common assays for measuring plasma TAC and the latest findings on dietary modulation of plasma redox status. Finally, the feasibility of the 'TAC concept' as an innovative tool for investigating the association between diet and oxidative stress is discussed.

Antioxidants↗
PubMed1993

Brain natriuretic peptide and fluid volume homeostasis--studies during cardiopulmonary bypass surgery.

Brain natriuretic peptide (BNP) is a recently identified cardiac ventricular hormone with diuretic, natriuretic and vasorelaxant properties. The aim of our study was to examine whether serial changes in endogenous levels of BNP were associated with fluid volume homeostasis following cardiopulmonary bypass. We studied nine patients undergoing elective cardiac surgery for the repair of cardiac abnormalities requiring cardiopulmonary bypass. Urinary levels of cyclic guanosine monophosphate (cGMP), sodium, urine output, fluid balance, and plasma levels of BNP, aldosterone, plasma renin activity (PRA) and central venous pressure (CVP) were measured before, during and after cardiopulmonary bypass. Basal pre-operative plasma BNP levels were highly elevated in all nine patients with cardiac abnormalities. During bypass, pre-operative levels of BNP, urinary cGMP and plasma aldosterone decreased significantly (p < 0.05), whereas pre-operative levels of urinary sodium and PRA were slightly reduced. During recovery following bypass levels of urinary cGMP, sodium, PRA and aldosterone returned to basal pre-operative values, whereas post-operative levels of plasma BNP were found to be three-fold below basal pre-operative levels. CVP (4.3 +/- 0.2 mmHg) during the onset of bypass increased significantly (p < 0.05) at the end of bypass (9 +/- 0.3 mmHg) followed by a modest increase post-operatively (10 +/- 0.4 mmHg). After operation only BNP had a significant correlation with urine output (r = -0.82, p < 0.02) and net fluid balance (r = -0.84, p < 0.01), whereas urinary cGMP, PRA and aldosterone all exhibited a non-significant correlation with urine output.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldosterone↗
PubMed1984

Effective use of total parenteral nutrition in an ileostomy patient.

Several goals were achieved through nutritional support of a 52-year-old female ileostomy patient who was admitted with dehydration, clinical malnutrition of a kwashiorkor type, and excessive body fat. Initially, parenteral nutrition was used to stabilize the patient. A total parenteral nutrition solution was calculated to meet the patient's energy, protein, mineral, vitamin, and fluid needs, including special needs resulting from the loss of fluid and electrolytes via the ostomy. The patient was subsequently weaned onto enteral feeding and then onto food plus an enteral mineral and vitamin drip. Nutritional status was improved (e.g., positive nitrogen balance was established); the patient absorbed nutrients better; and some lean body mass was restored, while total body weight decreased.

Body Weight↗
PubMed2001

Effect of fluid and sodium removal on mortality in peritoneal dialysis patients.

UNLABELLED: Effect of fluid and sodium removal on mortality in peritoneal dialysis patients. BACKGROUND: Adequacy of peritoneal dialysis (PD) traditionally is assessed using Kt/V(urea) and total creatinine clearance (TCC). However, this approach underestimates the importance of fluid and sodium removal. The aim of this study was to determine the effect of fluid and sodium removal on morbidity and mortality in PD patients. METHODS: One hundred twenty-five PD patients were monitored for three years from the beginning of the treatment. The effects of demographic features, comorbidity, peritonitis rate, blood pressure, medications, blood biochemistry, peritoneal membrane transport characteristics, residual renal function (RRF), Kt/V(urea), TCC, normalized protein nitrogen appearance (nPNA), and removal of sodium and fluid on mortality were evaluated. Total and cardiovascular hospitalization rates were also recorded. A Cox proportional hazards model was used to determine factors predicting mortality. RESULTS: In the Cox model, comorbidity, total sodium and fluid removals, hypertensive status, serum creatinine, and RRF were independent factors affecting survival. In contrast, Kt/V(urea) or TCC did not affect the adjusted survivals. Total sodium and fluid removal and hypertensive status also significantly influenced the hospitalization rate. Systolic and diastolic blood pressures were negatively correlated with total fluid (P < 0.001) and sodium removal (P < 0.001). CONCLUSIONS: Together, these findings suggest that removal of sodium and fluid is a predictor of mortality in PD patients, whereas Kt/V(urea) and TCC are not factors. Adequate fluid and sodium balance is crucial for the management of patients on PD.

Adolescent↗
PubMed1989

General principles of fluid therapy in small animal medicine.

The clinician's knowledge about total body water distribution and the appropriate choice of fluids for treatment can have an important effect on the eventual outcome of his or her patients. The ability to calculate fluid deficits and to compute infusion rates appropriately is an essential aspect of top-quality patient care. The principles of fluid therapy that were provided in this article should provide one with a logical and practical means for prescribing fluid treatments.

Animals↗