The objective of this study was to analyze differences in thermoregulation and water balance under conditions of heat load and water restriction between fat-tailed sheep (S) and Kacang goats (G). The daily intakes of food and water, daily outputs of urine and feces, rectal temperature, respiration rates, hematocrit values and plasma volumes of five shorn S and five G were determined over 10 days of four consecutive experimental conditions: (1) indoor – unrestricted water; (2) indoor – restricted water; (3) 10 h sunlight exposure – unrestricted water; and (4) 10 h sunlight exposure – restricted water. There was a 6- to 7-day adjustment period between two consecutive conditions. The study was conducted during the dry season. The animals were placed in individual cages, fed chopped native grass ad libitum and had free access to a urea–molasses multi-nutrient block. Under sunlight exposure with unrestricted water availability, S and G record an increase in the maximum rectal temperatures from 39.2°C to 40.2°C and from 39.9°C to 41.8°C, respectively. The thermoregulatory strategy used by S for maintaining a lower rectal temperature mostly depends on increasing the respiration rate as the main cooling mechanism. On the other hand, G apparently used sweating as the predominant mechanism for cooling. Moreover, G seemed to be more tolerable to higher heat storage and body temperature than S with a significant increase in plasma volume (P < 0.01), and this may be beneficial to the animals for the prevention of water loss. Under restricted water condition in either indoor or outdoor environment, both species decreased their plasma volume significantly, but rectal temperatures were relatively maintained. In all experimental conditions, the daily total water exchanges (ml/kg0.82 per day) of S were significantly higher than G (P < 0.01). However, when the percentages of the total daily water exchange were considered, the water lost through urination (38% to 39%), defecation (11% to 14%) and evaporation (46% to 49%) by S and G was not significantly different. Therefore, the results from this study clearly showed that S and G have different homeostatic strategies for the regulation of body temperature and fluid to cope with heat load and water restriction. These differences may have an important impact on the production management of S and G.

The change in blood and plasma volume following ingestion of glucose solutions of varying concentrations was estimated in twelve healthy male volunteers. Subjects consumed, within a 5 min period, 600 ml of a solution containing 0, 2, 5 or 10 % glucose with osmolalities of 0 (sd 0), 111 (sd 1), 266 (sd 7) and 565 (sd 5) mOsm/kg, respectively. Blood samples were collected over the course of 1 h after ingestion at intervals of 10 min. After ingestion of the 2 % glucose solution, plasma volume increased from baseline levels at 20 min. Plasma volume decreased from baseline levels at 10 and 60 min after ingestion of the 10 % glucose solution. Heart rate was elevated at 10 and 60 min after ingestion of the 10 % glucose solution and decreased at 30 and 40 min after ingestion of the 2 % glucose solution relative to the average heart rate recorded before drinking. It is concluded that ingestion of hypertonic, energy-dense glucose solutions results in a decrease in plasma and extracellular fluid volume, most likely due to the net secretion of water into the intestinal lumen.

In the Eisenmenger syndrome, indirect estimation of blood volumes may provide quite inaccurate information when seeking to define therapeutic strategies. With this in mind, we analyzed directly the red cell mass, plasma volume, and total blood volume in patients with pulmonary hypertension associated with congenital cardiac defects and erythrocytosis, comparing the results with the respective estimated volumes, and examining the changes induced by therapeutic hemodilution.

Thus, we studied 17 patients with the Eisenmenger syndrome, aged from 15 to 53 years, in the basal condition, studying 12 of them both before and after hemodilution. We also investigated five individuals with minimal cardiac lesions, aged from 14 to 42 years, as controls. Red cell mass and plasma volumes were measured using [51 chromium]-sodium chromate and [131iodine]-albumin respectively. Hemodilution was planned so as to exchange 10% of the total blood volume, using 40,000 molecular weight dextran simultaneously to replace the removed volume. The mean values of the red cell mass, plasma volume and total blood volume as assessed by radionuclide techniques were 32%, 31% and 32% higher than the respective volumes as estimated using empirical mathematical formulas (p < 0.002). The measured total blood volume was also 19% higher in the patients compared with controls. Following a period of 5 days after hemodilution, we noted a 13% reduction in red cell mass (p = 0.046), and 10% reduction in total blood volume (p = 0.02), albeit with no changes in the plasma volume.

We conclude that direct measurement of blood volumes is useful for proper management of these patients, and provides results that are considerably different from those obtained by empirical estimations.

The present study tested the hypothesis that multi-frequency bioelectrical impedance analysis (MFBIA) can be used to provide reasonable estimates of body mass, total body water (TBW), extracellular fluid volume (ECFV) and plasma volume (PV) at rest, during exercise-induced dehydration and subsequent recovery. Seven exercise-conditioned horses were administered indicators for measurement of resting TBW, ECFV and PV. MFBIA measurements at 24 frequencies between 5 and 280 kHz were obtained at rest, during prolonged submaximal exercise and for up to 13 h of recovery with food and water provided. Impedance–frequency response curves were described by a double-exponential decay equation from which coefficients were used, together with height and length, to generate predictive equations for estimating body mass, TBW, ECFV and PV. Predictive equations for body mass, ECFV and PV provided reasonable estimates of the parameter at rest and during exercise and recovery that were within 6% of absolute values determined using indicators. Despite the inherent error in estimating absolute volumes, the technique allowed accurate (within 1%) determination of the change in compartment volumes within individual horses over time. The number of frequencies at which impedance was measured could be reduced to seven without sacrificing the accuracy of the impedance–frequency relationships or the predictive equations – this enabled a 70% reduction in data-acquisition time (to ∼35 s) for each MFBIA measurement series. It is concluded that MFBIA can be used in individual horses to track changes in compartmental hydration status resulting from dehydration and rehydration.

Physiological adaptation including expansion in plasma volume is exaggerated in women with twin pregnancies. In singleton pregnancy and multiparous twin pregnancies there is an association between plasma volume expansion and birth weight, but this is not so in primigravid twin pregnancies. Women with twin pregnancies have a similar dietary intake to singleton pregnancies, but it is not known whether there are differences with parity or zygosity. Absorption and utilisation of nutrients may be increased to meet demands for extra fetal growth. Nutrient supply and plasma volume expansion will be further discussed and their association with birth weight presented.