Infusion Of Distilled Water Research Articles

Conditioned feeding responses in sheep to flavoured foods associated with sulphur doses

AbstractA study was conducted to determine whether sheep form conditioned flavour aversions (CFAs) or preferences (CFPs) for food flavours associated, respectively, with excessive or appropriate concentrations of sulphur (S) and also whether the rate of formation and strength of CFAs and CFPs are dependent on the animal's initial S status or the level of administration of S. In experiment 1, 48 mature ewes were conditioned to associate a new food containing a novel flavour with an infusion of S delivered intra-ruminally, or the same food containing another novel flavour with an infusion of distilled water. The same flavours were then used in experiment 2. At the end of each conditioning period, the relative preference for the two flavoured foods was determined by measuring the amount of each food ingested during a two-choice, 20-min preference test. Experiment 1 consisted of two phases. In phase 1 each conditioning period lasted for 5 days and was repeated four times, whereas in phase 2 the conditioning period lasted for 8 days and was repeated three times.In experiment 1 the sheep were initially in an S-adequate state. In experiment 2, the sheep were re-randomized to treatments and started in an S-depleted state. The conditioning periods also lasted for 8 days and were repeated three times. There was no evidence to support the hypothesis that sheep develop CFAs or CFPs to food flavours associated with S doses in phase 1 of experiment 1. In phase 2, however, sheep formed CFAs towards the food with the flavour they had come to associate with administration of high levels of S. Repeated exposure to the flavour associated with high levels of S led to stronger aversions and there was an interaction between the S dose level and conditioning periods, indicating that the rate of development of these CFAs was highest for the highest S dose levels. The differences between results of phase 1 and 2 were probably due to the different numbers of reinforcements and different intervals between specific flavour/dose associations.In experiment 2 there was no evidence for the development of CFPs or CFAs to food flavours associated with S doses. The apparent indifference of the sheep to S was probably due to their responding more to their previous experience of the food flavours than to their S status. Spearman rank correlations on flavour preferences indicated that conditioned flavour responses formed in experiment 1 persisted in individual sheep when they were allocated at random into their new treatments in experiment 2 and influenced or masked the formation of new associations. This demonstration of ‘carry-over’ effects highlights the importance of considering an animal’s previous experience of flavours and their associations with post-ingestive consequences when coming to conclusions concerning current development of CFAs and CFPs. These results may also have more general implications for feeding studies in animals that are randomized into treatment groups without regard to their previous feeding experiences.

Factor from Swamp Water Induces Hatching in Eggs ofAnopheles diluvialis(Diptera: Culicidae) Mosquitoes

Anopheles quadrimaculatus Say, An. smaragdinus Reinert, and An. diluvialis Reinert mosquitoes are recently described sibling species that occur in northern Florida where the adults are sympatric but larvae develop in different aquatic habitats. The hatching dynamics of these species showed that An. diluvialis utilizes a hatching stimulus that occurs in the substrate in intermittently flooded swamps. Most eggs of An. quadrimaculatus and An. smaragdinus hatch spontaneously in distilled water, but most eggs of An. diluvialis do not. Most An. diluvialis eggs hatch when placed in swamp water or when placed in an infusion of distilled water, leaf litter, and detritus from intermittently flooded swamps, suggesting the presence of an exogenous compound(s) as a hatching factor for this species. Percentage of egg hatch was largest in infusions made from swamp soil and in hexane extracts of swamp water, indicating that the hatching factor is a chemically stable organic substance. Because this phenomenon was not observed with water from lakes, ponds, springs, spring outlet streams, and rivers, An. diluvialis appears to require the hatching factor to facilitate egg hatch when intermittently flooded swamps are inundated. This article reports an exogenous compound being exploited as a hatching stimulus by an Anopheles mosquito.

Coordination of swallowing and phases of respiration during added respiratory loads in awake subjects.

In order to test the hypothesis that different types of respiratory mechanical loads may differently modify the coordination of respiration and swallowing, we investigated the coordination of respiration and swallowing during resistive and elastic loads in 14 healthy subjects. Ventilation was monitored with a pneumotachograph and reflex swallowing was elicited by continuous infusion of distilled water into the pharynx (3 ml/min) and recorded on a submental electromyogram while the subject breathed through a device with a flow-resistive load (180 cm H2O/L/s), an elastic load (70 cm H2O/L), or without any external load. We found that addition of a flow-resistive load did not influence the frequency of swallowing, whereas addition of an elastic load caused a significant increase in swallowing frequency during continuous infusion of water. Analysis of the timing of swallowing in relation to respiratory cycle phase revealed that with flow-resistive loading, swallows occurred preferentially during the inspiratory-expiratory (I-E) transition, whereas with elastic loading, swallows occurred preferentially during the expiratory-inspiratory (E-I) transition. Signs of laryngeal irritation were observed most often during the elastic loading following E-I swallows. These results indicate that different types of respiratory mechanical loads can differently modify this coordination of respiration and swallowing, and suggest that the coordination may be compromised more with elastic loading than with flow-resistive loading.

Intravascular β-amyloid infusion increases blood pressure: implications for a vasoactive role of β-amyloid in the pathogenesis of Alzheimer's disease

Hypertension has been recognized as a risk factor for Alzheimer's disease (AD). Moreover, serum β-amyloid (Aβ) levels are elevated in several mutations linked to familial AD, as well as in some sporadic AD individuals. To determine the in vivo effects of Aβ on blood pressure, Aβ1–40 was infused intra-arterially into anesthetized rats. For all animals, strong correlations exist between pre-infusion mean arterial blood pressure (MAP) and post-arterial infusion increases in blood pressure. In spontaneously hypotensive animals, Aβ infusion resulted in substantial increases in MAP compared to vehicle distilled water infusion. Aβ1–40 was also able to accelerate MAP return from induced hypotension, but infusion of Aβ1–42, or rat amylin had no such effect. These results provide evidence that circulating Aβ1–40 can exert vasopressor actions in vivo. Moreover, they suggest a pathophysiologic role for vascular Aβ in AD that precedes Aβ deposition and dementia onset.

Hypercapnia enhances the development of coughing during continuous infusion of water into the pharynx.

We investigated the effects of increasing CO2 ventilatory drive on the coordination of respiration and reflex swallowing elicited by continuous infusion of distilled water into the pharynx (2.5 ml/min) in 11 normal subjects. Ventilation was monitored using a pneumotachograph and swallowing was recorded by submental electromyogram. The CO2 ventilatory drive was increased by addition of external dead space, while ventilation, the frequency of swallows, and the timing of swallows in relation to the phases of the respiratory cycle were measured at steady-state conditions. We found that the CO2 ventilatory response is not influenced by continuous reflex swallowing but that hypercapnia influences the timing and frequency of these swallows. Signs of aspiration were never observed during continuous infusion of water at eucapnia, but seven of 11 subjects showed laryngeal irritation and/or pending aspiration during hypercapnia, and the incidence of laryngeal irritation was higher the greater the PCO2. Detailed analysis of laryngeal irritations consisting of single coughs in seven subjects revealed that the majority of laryngeal irritations occurred when swallows coincided with expiratory-inspiratory transition or when swallows coincided with inspiration, whereas laryngeal irritation after an expiratory swallow was never observed. These results suggest that the automatic respiratory control system is not influenced by continuous swallowing but that the coordination of swallowing and respiration may be compromised during hypercapnia.

Natriuresis caused by increased carotid Na+ concentration after renal denervation.

The renal effects of a selective estimated 3 mM increase in the concentration of Na+ in blood perfusing the brain was investigated in conscious dogs with surgically denervated kidneys. In split-infusion experiments the concentration of Na+ in carotid plasma was increased by a bilateral carotid infusion of hypertonic NaCl combined with an infusion of distilled water into the caval vein. In control experiments the same load of NaCl and water was administered as an isotonic solution into the carotid and jugular vessels. Peak rate of Na+ excretion was significantly higher during split infusion (156 +/- 19 mumol/min) compared with control (89 +/- 14 mumol/min). Renal excretion of urodilatin increased in both series. Renal excretion of endothelin immunoreactivity increased significantly more during split infusion (20 +/- 6 pg/min) than during control (9 +/- 3 pg/min). It is concluded that the natriuretic response to minute increases in Na+ concentration of carotid plasma is intact after renal denervation. Furthermore, endothelin may be involved in the excess excretion observed.

Cardiovascular Responses to Gastric Hypo-Osmolar Stimulation in Anesthetized Dogs.

We compared the cardiovascular response to the gastric infusion of distilled water (DI) with that to the gastric infusion of 0.9% saline (SI) and gastric ballooning with 37 degrees C water (BA) through a gastric fistula in splenectomized mongrel dogs (n = 7). DI, and SI amounting to 5% of body wt and the same volume of water were infused in approximately 20 s through the tube and responses in mean arterial pressure (MAP), CVP, heart rate (HR), and intra-esophageal pressure (EP) were monitored continuously. After DI, SI, and BA, the measured variables showed significant increases and attained maximal increases at about 2 min after the treatments. After DI, the maximum elevation in MAP was 21.3 +/- 1.9 mmHg and 2 times higher than in SI and BA. The corresponding value in CVP was 5.0 +/- 0.3 mmHg and 2-3 times higher than with SI and BA, and HR increased by 26.1 +/- 3.0 beats/min showing 3 to 6 times larger increases compared with SI and BA. These gastro-cardiovascular reflexes were abolished after subdiaphragmatic truncal vagotomy. These findings suggest that both the mechanical and osmotic stimuli to the stomach induce cardiovascular reflexes and that the vagus is involved in the reflex.

Ovine fetal swallowing and behavioral state responses to sublingual water.

Ovine fetal swallowing primarily occurs in bouts of activity associated with low voltage electrocorticogram activity and breathing movements. Despite similar rates of electromyographic swallowing activity, there are significant differences in the net esophageal fluid flow among fetuses. To determine if variations in the volume of fluids accessible to the fetus (amniotic fluid, lung fluid, salivary secretions) affect fetal swallowing, we studied the effects of sublingual distilled water infusions on ovine fetal swallowing rates and esophageal flow. Seven pregnant ewes at 127 +/- 2 days gestation were chronically instrumented with maternal and fetal vascular catheters, fetal electrocortical, electro-ocular and electromyograph electrodes, an esophageal flow probe and a sublingual infusion catheter. Following a 2-hour control period, consecutive sublingual infusions of room temperature distilled water (10 and 20 ml/kg/h) were administered for 2 h each. In response to sublingual infusions, fetal plasma sodium (142.5 +/- 0.5 to 140.8 +/- 0.8 mEq/l), chloride concentrations (109.2 +/- 0.4 to 107.7 +/- 0.7 mEq/l) and osmolality (302 +/- 2 to 298 +/- 2 mOsm/kg) decreased significantly. Swallowing activity and esophageal flow did not change significantly from basal values (47 +/- 9 swallows/h, 19.2 +/- 4.2 ml/h) during the sublingual infusions. However, fetal low-voltage electrocortical activity increased significantly during both infusion periods (42 +/- 3 to 56 +/- 6%). Sublingual distilled water infusion decreases fetal plasma osmolality and alters fetal behavioral state without affecting swallowing frequency or esophageal flow.

Intraruminal rehydration of ovine fetuses

During oral rehydration of adult mammals, oropharyngeal stimulation, the act of swallowing, and/or gastric factors contribute to a rapid decrease in plasma arginine vasopressin (AVP) that precedes plasma osmolality changes. To determine whether similar mechanisms are present in the developing fetus, six chronically prepared ovine fetuses were rehydrated with intraruminal (IR) distilled water infusions (1 ml.kg-1.min-1 for 60 min) after 43 +/- 3 h of maternal water deprivation. In response to maternal dehydration, significant increases were noted in maternal and fetal mean plasma osmolalities, sodium and AVP concentrations, and fetal urine osmolality. As estimated by hematocrit, fetal intravascular volume decreased by 11%. Fetal rehydration via IR distilled water infusion evoked a significant decrease in fetal plasma osmolality but no change in urine osmolality. Unexpectedly, fetal arterial blood pressure increased and arterial PO2 decreased while fetal hematocrit indicated a further 7% decrease in intravascular volume after the IR infusion. There was a nonsignificant trend toward increased fetal glomerular filtration rate, urine volume, and plasma AVP concentrations. Identical IR water infusions to five euhydrated fetuses resulted in significant decreases in fetal plasma osmolality and increases in glomerular filtration rate, urine flow, and osmolar excretion. The euhydrated fetuses also exhibited significant increases in mean arterial blood pressure and hematocrit and decreased fetal arterial PO2. These results indicate that IR water does not suppress AVP secretion in the dehydrated ovine fetus. Rather, both euhydrated and dehydrated fetuses exhibit an idiosyncratic vasoconstrictive response to IR water.

Effects of Partial Paralysis on the Swallowing Reflex in Conscious Humans

The ability to swallow may be affected by administration of a small dose of muscle relaxant. To test the hypothesis that a subparalyzing dose of a muscle relaxant can impair swallowing, effects of partial paralysis produced by pancuronium on the swallowing reflex were investigated in eight conscious subjects. The swallowing reflex was induced by a bolus injection or a continuous infusion of distilled water into the mesopharynx. The swallowing function was assessed by electromyogram of suprahyoid muscles (EMGSH), mesopharyngeal pressure (Pmeso), and hypopharyngeal pressure (Phypo). Peripheral muscle activity was simultaneously determined by train of four ratio (TOFR) of hypothenar muscles to electrical stimulation of ulnar nerve and by hand grip strength (HGS). Following control measurements, measurements during partial paralysis and after recovery from partial paralysis were performed after intravenous administration of pancuronium 0.02 mg/kg. Partial paralysis significantly depressed EMGSH (bolus injection 44.1 +/- 10.0%, continuous infusion 55.9 +/- 10.2% of control value, P less than 0.01). Pmeso also significantly decreased (bolus injection 64.9 +/- 6.7 to 47.8 +/- 5.8 mmHg, P less than 0.01; continuous infusion 63.4 +/- 7.7 to 52.5 +/- 5.8 mmHg, P less than 0.05). The TOFR of peripheral muscles decreased to 81.4 +/- 6.7% of control value (P less than 0.01), and HGS was reduced from 44.6 +/- 1.9 to 39.4 +/- 2.0 kg (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Possible role of the stomach in enteroinsular axis in rats

To elucidate the possible role of the stomach in enteroinsular axis, rats had both an inflow gastric cannula and an outflow diversion cannula and a duodenal inflow cannula. The effects of intragastric infusion of glucose (1 mL in 10% solution) or mannitol (1 mL in 10% solution) on blood glucose and plasma insulin responses to subsequent intraduodenal glucose (1.5 g/kg in 10% solution) or amino acids (1.0 g/kg in 10% solution) infusion were investigated. Blood glucose and plasma insulin responses to intraduodenal amino acids were not altered by intragastric infusion of glucose or mannitol. However, higher blood glucose and lower plasma insulin responses to intraduodenal glucose were observed in the rat with intragastric infusion of glucose or mannitol compared with controls (intragastric infusion of distilled water). This phenomenon was abolished in the rat with preadministration of phentolamine. These results suggest that intragastric tonicity may suppress glucose-induced insulin secretion, probably through the α-adrenergic mechanism in the rat.

Effect of intrauterine iodine infusion on luteal function and blood PGF 2a concentration in cycling goats

Studies were conducted to determine the effect of iodine infusion on the luteal function of goats, as evident by blood progesterone concentration, and on plasma PGF 2a levels. Ten cycling mixed breed goats were synchronized for estrus by PGF 2a (5 mg) and given a single intrauterine iodine infusion on day 5 and on day 15 of the estrous cycle. Iodine infusion on day 5 (group II) resulted in shorter estrous length (8.2 days) and a 7-fold increase in plasma PGF 2a concentration as compared to control animals (group I) given distilled water infusion. Similar infusion on day 15 (group III), on the other hand, failed to alter the estrcus cycle length but induced a moderate increase in PGF 2a concentration which lasted only for a brief period. The progesterone levels declined concomitantly as PGF 2a levels rose after iodine infusion in group II animals but failed to decline until after 24 hours in group III animals. The studies indicate that the endometrium reacts to the chemical stimuli and releases PGF 2a which, in turn, alters the luteal function.

Volume regulatory loss of Na, Cl, and K from rat brain during acute hyponatremia.

This study quantitatively evaluates the contribution of tissue Na, Cl, and K loss to brain volume regulation during acute dilutional hyponatremia (DH) and examines the mechanism of Na loss. DH was produced in pentobarbital sodium-anesthetized rats by intraperitoneal infusion of distilled water and brain water and electrolytes analyzed 30 min, 1 h, 3 h, 4 h, or 6 h later. The rate of Na and Cl loss was greatest during the first 30 min of DH (0.43 and 0.47 meq X kg tissue dry wt-1 X min-1, respectively). Net loss of Na and Cl was maximal after 3 h of DH. K loss was slower, achieving significance after 3 h. Electrolyte loss was sufficient to account for observed brain volume regulation after three or more hours of DH. Measurements of 22Na influx and efflux across the blood-brain barrier showed that barrier permeability to Na is unchanged during DH. Analysis of results using a two-compartment model of plasma-brain exchange suggests that loss of brain Na during DH does not result solely from a shift of electrolyte across the blood-brain barrier to plasma, and thus provides indirect evidence for an additional pathway for Na loss, presumably via cerebrospinal fluid.

Changes in serum and bile bilirubin induced by acute hemolysis

The association between chronic hemolysis and pigment gallstones is well known but not adequately understood. To define the source and quantity of insoluble pigment resulting from hemolysis, hepatic bile in miniature swine was studied during the intravenous infusion of distilled water. Concentrations of both total bilirubin and insoluble unconjugated bilirubin rose rapidly during the first 2 hr to levels more than seven times above control values. In the third hour, unconjugated pigment continued to increase while total bilirubin plateaued, suggesting that glucuronidation or transport maxima had been reached. Elevations in unconjugated bilirubin could not be accounted for by the intrabiliary hydrolysis of conjugated bilirubin. It is concluded that hemolysis results in the secretion of large quantities of insoluble bilirubin directly into bile. This process may represent an important step in the development of pigment polymers or precipitates.

The satiety effects of intragastric macronutrient infusions in fatty and lean Zucker rats

To evaluate satiety in the hyperphagic, genetically obese Zucker “fatty” (fafa) rat, food-deprived fatty and lean (FaFa) control rats were given equicaloric intragastric infusions consisting largely of fat, carbohydrate, or protein. Relative to distilled water infusion, these infusions resulted in immediate reductions of food intake in both fatty and lean rats allowed to feed 20 min post-infusion. Cumulative food intakes remained reduced throughout the 2 hr period of observation. Thus, despite its hyperphagia, the fatty rat is responsive to the satiating effect of infused nutrients. However, the relative satiating effectiveness of the macronutrient infusions differed for the two genotypes. In lean rats, the different macronutrient infusions resulted in equivalent reductions of feeding. In contrast, in fatty rats, fat was the least satiating and protein was the most satiating macronutrient. Moreover, compared to lean rats, fatty rats displayed less initial suppression of feeding after fat infusion and greater overall suppression after protein infusion. These effects are consistent with the long-term feeding behavior of the fatty rat for the different macronutrients and may be related to pre- and postabsorptive metabolic alterations that have been documented in this animal.

Control of evaporative heat loss during changes in plasma osmolality in the cat.

1. The effects of intravenous infusion of hypertonic saline and distilled water into normally hydrated and dehydrated cats have been examined at both high and neutral ambient temperatures.2. In hydrated cats measurements of body temperature (T(b)) and evaporative heat loss (e.h.l.) show that infusion of 30% saline (1.5 ml./kg) at an ambient temperature of 38 degrees C, lowers e.h.l. by an average of 0.21 W/kg (P < 0.001) and elevates T(b) by 0.43 degrees C (P < 0.01).3. At 25 degrees C alterations in these two parameters were in the same direction, though not statistically different from pre-infusion levels (P > 0.05).4. Infusion of distilled water (15 ml./kg) into dehydrated animals produced significant increases in e.h.l. (+0.35 W/kg, P < 0.001) and reductions in T(b) (-0.45 degrees C, P < 0.001) at 38 degrees C. No significant effects were observed at 25 degrees C.5. Infusion of water into normally hydrated animals at 38 degrees C also significantly increased e.h.l. (+0.13 W/kg, P < 0.05) and insignificantly lowered T(b) (-0.03 degrees C, P > 0.05).6. Local heating of the preoptic hypothalamic area in four animals indicated that hypertonic saline infusion into normally hydrated animals caused a reduction in the slope and displacement to the right of the relationship between hypothalamic temperature and e.h.l.7. Conversely, water infusion into dehydrated animals increased the slope and shifted this relationship to the left.8. These experiments provide evidence for an osmotic interaction in body temperature regulation which acts to alter the responsiveness of the hypothalamus to increasing temperature. This osmotic component may be an important factor in the alterations in thermoregulation seen in dehydrated animals.

Evaluation of gastric emptying by a simple isotope technique. A methodological study in the dog.

The gastric emptying of a fluid standard meal labelled with 99mTc-DTPA has been studied in dogs, using a scintillation detector. The method was assessed in a series of in vivo and in vitro experiments. The gastric emptying patterns were visualized as time-activity curves. In the initial phase, the typical curves showed a rapid emptying within 2-5 min after start of the meal, followed by a more varied emptying and a subsequent steady emptying in the basic phase. Duplicate tests showed acceptable reproducibility. The initial emptying varied among individuals, whereas the basic emptying did not vary significantly. Combined evacuation/isotope gastric emptying studies showed that the external counting technique produced results comparable to those obtained by evacuation. Short-lasting spikes and plateau-like dislocations were observed in the curves, indicating peristalsis and duodenogastric reflux, respectively. The observed data are comparable with those obtained in man when using a gamma camera. Gastric emptying tests, carried out during continuous infusion of distilled water, 20% soya bean oil, or 25% glucose into various parts of the proximal gastrointestinal tract, showed that in dogs inhibitory 'receptors' for fat and glucose were located in the small intestine distal to the ligament of Treitz.

The Effect of Bicarbonate and Distilled Water on Sickle Cell Trait Hematuria and in Vitro Studies on the Interaction of Osmolality and pH on Erythrocyte Sickling in Sickle Cell Trait

The effect of intravenously administered distilled water was examined alone and during alkalization in a patient with gross hematuria associated with the sickle cell trait. On each of 4 occasions hematuria ceased promptly after the infusion of distilled water. Bicarbonate therapy also consistently decreased hematuria.In vitro studies on erythrocytes from another patient with sickle ceil trait and hematuria demonstrated that slight increases in urinary pH similar to those that occur in the urine during alkalization can reverse or prevent erythrocyte sickling in the sickle cell trait.If patients with the sickle cell trait are hydrated adequately and have a good rate of urine flow distilled water can be given intravenously with virtually no danger of acute tubular necrosis secondary to erythrocyte hemolysis.

Evidence for both luminal and systemic factors in the control of rat intestinal epithelial replacement.

1. Isolation of a self-emptying sac of rat small intestine in vivo halved the cell production rate in the crypts of Lieberkühn as measured by colchicine blockade. 2. Starvation for 48 h of rats with isolated intestinal sacs caused a further halving of cell production rate in the sac. 3. Infusion of distilled water into isolated intestinal sacs for 72 h caused a similar degree of stimulation of cell production in sacs in fed and starved rats, suggesting that the fall in cell production rate on starving a rat bearing an isolated sac is not due to t-e non-availability of the substances required for cell synthesis. 4. The possible contribution of innervation of the gut, and of systemic hormonal influences, on intestinal epithelial replacement is discussed.

Failure to trigger intravascular coagulation by water-induced haemolysis in rabbits.

Massive haemolysis induced by infusion of distilled water into rabbits did not produce signs of intravascular coagulation in healthy rabbits, nor did haemolysis accentuate thromboplastin induced DIC. Some possible mechanisms for these unexpected findings are briefly discussed.