Effect of self-determined intravenous infusion of hypertonic NaCl on Na appetite of sheep.

The time delay between a rapid, systemically produced change in sodium balance and a change of voluntary sodium intake was examined in sodium-deficient sheep with a parotid fistula. They were trained to barpress to replace a daily sodium deficit of 300–500 mmol. During basal conditions on different days, each delivery to a drinking cup consisted of either a small or a large amount of NaHCO? solution. In the experimental situation, the small amount of NaHCO? was delivered to the cup, but total sodium delivered was made to equal that of the large amount by automatic concurrent infusion of hypertonic NaCl iv with each delivery to the cup. As a control, the concurrent iv infusion was .15 M NaCl, which had little influence on sodium balance. A significant difference in the cumulative number of deliveries between the hypertonic and isotonic NaCl infusion conditions occurred by 10–20 min. It is concluded that systemic injections of hypertonic NaCl are effective within 10–20 min in reducing the sodium appetite of Na-depleted animals. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of desalivation on drinking and air licking induced by water deprivation and hypertonic saline injections.

Previous studies show that desalivate (DS) rats drink more water than controls when maintained on a diet of dry food, but drink less than controls after a period of water deprivation. In the present series of studies, a total of 14 male and 2 female naive hooded rats served as Ss. Results show that DSs ate less food than sham operates (SHs), indicating that DSs' body fluids probably do not become as hyperosmotic as those of the SHs. When Ss were maintained on a moist mash during water deprivation, subsequent water intake and air licking were about the same for DSs and SHs. After combined food and water deprivation, both groups air-licked at greatly reduced rates. After subcutaneous injections of hypertonic saline, DSs air-licked just as much as SHs. It is concluded that DSs drink less after water deprivation because they eat less dry food than SHs during deprivation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stimulation of prostaglandin output from rat stomach by hypertonic solutions

A whole-cell preparation of rat stomach put out appreciable amounts of immunoassayable PGE. Buffers made hypertonic with either sodium chloride or mannitol effected several-fold increases in PGE output, while a comparable osmotic concentration of urea seemed to produce much less stimulation. Enhancement of PGE output by saline--hypertonic buffers was concentration-dependent. It is suggested that the osmolarity of the gastric contents may play a role in regulating gastric PG biosynthesis.     

Effect of variation in dietary NaCl intake on total and fractional renal blood flow in the normal and mercury-intoxicated rat

The influence of parasympathetic and sympathetic nerves on the parotid gland of the rat was investigated. It was found that both divisions of the autonomic nerves evoke secretion and probably also motor effects in this gland. Secretion elicited on sympathetic stimulation was mediated both via alpha- and beta-adrenoceptors, while motor effects were mediated via alpha-adrenoceptors. On stimulation of the autonomic nerves a lower duct pressure was reached in the parotid than in the submaxillary gland, and on sympathetic nerve stimulation the flow of saliva always started later from the parotid than the submaxillary gland. These findings are discussed in the view of the different arrangement of the myoepithelial cells in the 2 glands.     

Dopamine and sodium appetite: Antagonists suppress sham drinking of NaC1 solutions in the rat.

Sodium (Na) ingestion in rats depleted of Na is a strong, motivated behavior that is enhanced further when depleted rats are sham drinking. Dopamine plays a critical role in motivation, including reward associated with consumption of palatable tastes. The present studies assessed the role of dopamine in real and sham drinking of NaCl solutions after Na depletion with the diuretic furosemide (10 mg/kg). Dopamine (D2) receptor antagonists were evaluated (Haloperidol [0.1 mg/kg] and raclopride [0.2 mg/kg]), for their effects on 2 sham and real drinking of 0.3 M NaCl. Sham drinking was markedly reduced by both antagonists whereas real drinking was unaffected. These effects did not appear to be due to malaise or suppression of motor behavior because drug-treated animals were able to increase ingestion substantially when offered less concentrated NaCl (0.1 M). These results suggest that the positive motivating properties of NaCl stimulation in depleted, sham-drinking rats are mediated by central D2 receptors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of drinking history on food-deprived drinking in the rat.

Investigated the role of drinking during development in 40 male hooded Long-Evans rats. Experimental Ss were deprived of water during rearing; ingestion of lettuce provided for sufficient fluids. Body weight, feeding, drinking, and urine volume over successive food deprivation periods were compared with normally reared controls. The lettuce-reared Ss drank less water and ate less lettuce when food deprived, but did not differ from normal Ss in drinking or in lettuce intake when food was available ad lib. It is suggested that lettuce-reared animals drink water principally in response to fluid deficits. Other research indicates that the drinking of normally reared rats anticipates fluid deficits and is not initiated by events related to the need for water. The present results suggest that this anticipatory drinking is acquired. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Periprandial self-intravenous drinking in the rat.

Describes 4 experiments in which self-injected intravenous (iv) drinking (SID) of intact and desalivated male albino Wistar rats (N = 29) was studied over long periods in relationship with continuously recorded feeding of powdered chow. Periprandial episodes of SID were similar to those of oral drinkers, but the preprandial anticipatory component was increased in these permanently dehydrated (oliguric) Ss. The elimination of hedonic factors together with the observed responses to calorically or osmotically modified diets available ad lib or in restricted schedules (1 or 2 meals a day) emphasized the regulatory role of periprandial drinking. Ss that received injections in parallel with their SID-paired partners showed a nonreliable meal onset following iv water receipt; generally, meals remained taken in an idiosyncratic pattern. In the absence of food, SID Ss continued the rhythm of iv water ingestion. Results are discussed with reference to regulatory nature of drinking and to biological oscillator models. (34 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Renal renin output during continuous intracarotid infusions of iso- and hypertonic sodium chloride solutions in the rat

1. Unreduced human subcomponent C1q was shown by electrophoresis on polyacrylamide gels run in the presence of sodium dodecyl sulphate to be composed of two types of non-covalently linked subunits of apparent mol.wts. 69 000 and 54 000. The ratio of the two subunits was markedly affected by the ionic strength of the applied sample. At a low ionic strength of applied sample, which gave the optimum value for the 54 000-apparent mol.wt. subunit, a ratio of 1.99:1.00 was obtained for the ratio of the 69 000-apparent mol.wt. subunit to the 5400-apparent-mol.wt. subunit. The amount of the 54 000-apparent-mol.wt. subunit detected in the expected position on the gel was found to be inversely proportional to increases in the ionic strength of the applled sample. 2. Human subcomponent C1q on reduction and alkylation, or oxidation, yields equimolar amounts of three chains designated A, B and C [Reid et al. (1972) Biochem. J. 130, 749-763]. The results obtained by Yonemasu & Stroud [(1972) Immunochemistry 9, 545-554], which showed that the 69 000-apparent-mol.wt. subunit was a disulphide-linked dimer of the A and B chains and that the 54 000-apparent-mol.wt. subunit was a disulphide-linked dimer of the C chain, were confirmed. 3. Gel filtration on Sephadex G-200 in 6.0M-guanidinium chloride showed that both types of unreduced subunit were eluted together as a single symmetrical peak of apparent mol.wt. 49 000-50 000 when globular proteins were used as markers. The molecular weights of the oxidized or reduced A, B and C chains have been shown previously to be very similar all being in the range 23 000-24 000 [Reid et al. (1972) Biochem. J. 130, 749-763; Reid (1974) Biochem. J. 141, 189-203]. 4. It is proposed that subcomponent C1q (mol.wt. 410000) is composed of nine non-covalently linked subunits, i.e. six A-B dimers and three C-C dimers. 5. A structure for subcomponent C1q is proposed and is based on the assumption that the collagen-like regions of 78 residues in each of the A, B and C chains are combined to form a triple-helical structure of the same type as is found in collagens.     

Mechanism of NaCl and water reabsorption in the proximal convoluted tubule of rat kidney

The role of chloride concentration gradients in proximal NaCl and water reabsorption was examined in superficial proximal tubules of the rat by using perfusion and collection techniques. Reabsorptive rates (Jv), chloride concentrations, and transtubular potential difference were measured during perfusion with solutions (A) simulating an ultrafiltrate of plasma; (B) similar to (A) except that 20 meq/liter bicarbonate was replaced with acetate; (C) resembling late proximal fluid (glucose, amino acid, acetate-free, low bicarbonate, and high chloride); and (D) in which glucose and amino acids were replaced with raffinose and bicarbonate was partially replaced by poorly reabsorbable anions (cyclamate,sulfate, and methyl sulfate). In tubules perfused with solutions A and B, Jv were 2.17 and 2.7 nl mm-1 min-1 and chloride concentrations were 131.5 +/- 3.1 and 135 +/- 395 meq/liter, respectively, indicating that reabsorption is qualitatively similar to free-flow conditions and that acetate adequately replaces bicarbonate. With solution C, Jv was 2.10 nl mm-1 min-1 and potential difference was +1.5 +/- 0.2 mV, indicating that the combined presence of glucose, alanine, acetate, and bicarbonate per se is not an absolute requirement. Fluid reabsorption was virtually abolished when tubules were perfused with D solutions; Jv was not significantly different from zero despite sodium and chloride concentrations similar to plasma; chloride concentration was 110.8 +/- 0.2 meq/liter and potential difference was -0.98 mV indicating that chloride was close to electrochemical equilibrium. These results suggest the importance of the chloride gradient to proximal tubule reabsorption in regions where actively reabsorbable solutes (glucose, alanine, acetate, and bicarbonate) are lacking and provide further evidence for a passive model of NaCl and water transport.     

Taxon composition and genetic variation of water frogs in the Mid-Rh?ne floodplain

Natural hemiclonal hybrid lineages of water frogs reproduce by hybridogenesis, excluding one parental genome in the germ line and mating with the coexisting same parental species. Two such sexual host-hybridogen systems occur in the Rh?ne valley: the L-E system in the north, the P-G system in the south. Although these hybridogenetic complexes may overlap along the Rh?ne river, there is no evidence for a contact zone in our samples: only Rana ridibunda and R. esculenta were identified using protein electrophoresis. Whether the absence of R. perezi reflects a more southern distribution or its exclusive occurrence in other habitats, remains to be tested. Comparison of somatic and gonadal tissues reveals that gametogenesis of R. esculenta is of the L-E type: gametes carry ridibunda genomes. R. ridibunda apparently is not native, but was introduced by humans, and the R. esculenta in our samples is probably an immigrant from nearby L-E systems.     

Self-administered intravenous infusion of hypertonic solutions and sodium appetite of sheep.

Studied the effects of self-administered iv infusion of hypertonic NaCl, mannitol, glucose, urea, or isotonic NaCl on Na appetite. 22 Merino-Cross sheep were trained to barpress to replace Na deficits of 300–500 mmol. During basal conditions, each delivery to a drinking cup was 15 ml of .6 M NaHCO? (9 mmol). In the experimental situation, an iv infusion was given automatically with each delivery to the drinking cup. Ingestion of NaHCO? solution was significantly reduced by all hypertonic solutions, the largest decrease being caused by hypertonic NaCl or mannitol. The decreased intake was observed within 10 (with infusion of hypertonic NaCl, mannitol, or glucose) or 20–40 (with urea infusion) minutes, irrespective of whether water was concurrently available to drink. At 20 min, plasma Na was increased by hypertonic NaCl, decreased by mannitol or glucose, and not changed by urea. CSF Na concentration was increased by all hypertonic solutions. In regard to the "turn-off" of Na appetite by systemic infusion, data are consistent with the theory of neural cells within the blood–brain barrier responsive to changes of Na concentration or osmolality in their environment. In contrast, water intake was stimulated by hypertonic NaCl or mannitol but not by urea or glucose. Results suggest that the sensors involved in thirst (e.g., osmoreceptors) are in an area of the brain lacking the blood–brain barrier. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of pitting corrosion in NaCl solutions on the statistics of fracture of beryllium

The effect of pitting corrosion, occurring in NaCl solutions, on the bending behavior of commercial beryllium was studied. Three concentrations of NaCl solutions (0.01, 0.1, and 1 M) were used in the experiments. Bend specimens were exposed to these solutions for a total of 168 hours. Weibull statistics were used to analyze the experimental bend-strength data and were applied to the failure strength, displacement to failure, and yield strength. Samples exposed to the 1 M NaCl solution exhibited a high Weibull modulus, with a higher retained mean failure strength and displacement to failure. On the other hand, the samples exposed to the 0.01 and 0.1 M NaCl solution exhibited significantly lower mechanical property values and Weibull moduli, accompanied by a larger scatter in the failure strength and displacement to failure. The engineering yield strength of the samples did not change significantly with exposure to the NaCl solutions, although there was an increase in the scatter of the values. These effects on the mechanical properties were attributed to a decreasing propensity for the formation of localized deep pits and an increasing propensity for uniform shallow pitting with increasing NaCl concentrations. Scanning electron microscopy (SEM) was primarily used for quantifying these corrosion pitting effects. In addition, atomic-force microscopy (AFM) and potentiodynamic polarization experiments were also conducted to provide supportive evidence for the differences in the pitting behavior of the beryllium with different NaCl concentrations.     

Comparison of hypertonic saline solutions and dextran in dialysis-induced hypotension

The efficacy of three hypertonic saline solutions for treating dialysis-induced hypotension in a randomized, blinded, crossover clinical trial of 10 patients (a minimum of three cycles per solution) was compared. Dialysis-induced hypotension, defined as a decrease in systolic blood pressure of at least 10 mm Hg or systolic blood pressure less than 100 mm Hg, was treated with an iv bolus of either 10 mL of 23% saturated hypertonic saline, 30 mL of 7.5% hypertonic saline, or 30 mL of 7.5% saline with 6% dextran 70, each containing similar osmolar loads of 80, 80, and 100 mosM, respectively. All three solutions raised systolic blood pressure within 5 min (mean pretreatment systolic blood pressure, 87 mm Hg; mean posttreatment systolic blood pressure, 101 mm Hg; P < 0.05). The magnitude of the increase was greater with saturated hypertonic saline (15 mm Hg) and dextran 70 (17 mm Hg) compared with that with hypertonic saline (9 mm Hg; P < 0.05). At 10 min, dialysis-induced hypotension was less frequent with saturated hypertonic saline (incidence, 9%) compared with hypertonic saline (45%). Beyond 10 min, however, there was a trend toward a lower incidence of further dialysis-induced hypotension with dextran 70. There were no side effects. Given equal osmole loads, the more concentrated solution produced a greater increase in systolic blood pressure. The addition of an oncotic agent such as dextran may prolong the blood pressure response beyond 10 min. It was concluded that hypertonic saline solutions safely and effectively treat dialysis-induced hypotension.     

Behavioral effects of chemicals in drinking water.

In Exp I, 42 Ss (mean age 30.4 yrs) tracked a moving target and monitored lights after receiving sublingual drops that contained either water, sodium nitrate (4.5, 45, 450, or 4,500 ppm), or sodium fluoride (.1, 1, 10, or 100 ppm). Dosage levels equaled, exceeded, or fell below those of municipal waters. In Exp II, 20 females performed this task after receiving sublingual drops of the same test substances in a repeated measures design; dosage levels equaled or exceeded levels found in municipal waters by 100 or 500 times. Neither type nor amount of chemical affected primary task performance; however, after receiving sublingual drops in Exp I, Ss paid less attention to lights on their right. In Exp II, Ss made more errors and had longer response latencies after they received moderate and very high concentrations of test substances. It is concluded that challenge testing is a safe but effective technique for provoking and studying reactions to chemicals when combined with a sensitive measure of sensorimotor performance. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Abdominal vagotomy disrupts food-related drinking in the rat.

In 2 experiments with a total of 41 Sprague-Dawley albino rats, Ss with complete subdiaphragmatic bilateral transection of the abdominal vagus (Vgx-C) showed disordered food-related drinking when drinking water in temporal association with a meal of dry food after 5-hr food deprivation and when drinking water in association with a liquid meal after 24-hr food deprivation. The Vgx-C Ss drank after significantly longer latencies and drank significantly less water in 1 hr than did sham-vagotomized (Sham) Ss after eating the same size meal (solid or liquid). Ss with incomplete vagal transection (Vgx-I) ate and drank like Shams. Water intake of Sham and Vgx-I Ss correlated positively with the meal size of solid food, but the water intake of Vgx-C Ss did not. The failure of Vgx-C Ss to drink water normally when food was ingested was not due to failure of a food stimulus to reach the intestine, because Vgx-C and Sham Ss emptied equivalent volumes of liquid food from the stomach into the intestine within 10 min of food entering the stomach. Results indicate that the abdominal vagus is an important neurological substrate for food-related drinking in the rat. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Long-term self-intravenous "drinking" in the rat.

Results of a series of experiments show that male Wistar albino rats, when water was available only by intravenous self-injection, learned to rehydrate by pressing a lever even after desalivation and for periods up to 90 days. It appears that hydromineral regulation was occurring about a new, lower set point for body fluid content which was necessary for the onset and maintenance of intravenous "drinking." The regulatory nature of the operant was confirmed by appropriate modulation of operant rate to amount of reinforcement per leverpress and in tonicity of self-injected fluid. There seemed to be some "motivational deficits," and these Ss did not respond for intravenous water as the oral controls did when challenged with traditional intra- and extracellular thirst stimuli. More complex stimuli (e.g., heat and salty food) led to compensatory responding. While interoceptors alone seemed capable of eliciting the defense of a homeostatic hydromineral balance, the control over the operant was less precise than for normal oral drinking. (57 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Water-intake volume regulation in the rat: Schedule-induced drinking compared with water-deprivation-induced drinking.

Hungry rats drink extremely large amounts of water when they are intermittently fed small amounts of food (schedule-induced polydipsia). The present 5 experiments examined whether such animals are motivated to drink for long durations, to ingest large amounts of fluid, or to do both. When drinking-tube apertures were decreased to slow the rate of water ingestion, each of 8 female Sprague-Dawley rats spent more time drinking than when larger apertures were used (averages of 11.5 vs 7.8 min, respectively). The mean volumes ingested were not different. These equal volumes were generated by adjustment of each drink duration in accordance with ingestion rate even during the first few drinks of the sessions and when the drinking tubes were frequently switched (every 1–3 min) during the sessions. During drinking induced by water deprivation when food was concurrently available, restriction of the tube apertures reduced intake volumes by 18–29%. However, when food was not concurrently available during water-deprivation-induced drinking, regulation of intake volumes was comparable with that found during schedule-induced polydipsia. Data pose difficulties for theories that ascribe a crucial role to the motor aspects of schedule-induced drinking. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Occurrence of uranium in drinking water in the U.S

Uranium is found in ground and surface waters due to its natural occurrence. In some cases, its presence is due to human activities such as mining and milling uranium. Thus, it is also found in drinking water. The range of concentrations existing in drinking water supplies in the U.S. is tabulated and examined. The range of isotopic abundances are also listed. Projections from the available data lead to estimates that of the 59,812 community drinking water supplies in the U.S., 25-650 would exceed a uranium concentration of 20 pCi/l., 100-2000 would exceed 10 pCi/l. and 2500-5000 would exceed 5 pCi/l.     

Abdominal vagotomy inhibits osmotically induced drinking in the rat.

Results of a study with 35 male Sprague-Dawley rats show that after complete bilateral transection of the abdominal vagus (Vgx-C9), with the hepatic branch left intact, Ss drank later and less than normal after cellular dehydration induced by hypertonic saline. When access to water was delayed for 1 hr after cellular dehydration, Vgx-C Ss initiated drinking quickly with normal latency, but (a) a gastric water preload was a more effective stimulus for drinking suppression in Vgx-C than in normal Ss; (b) gastric emptying of a water or phenol red solution preload was more rapid in Vgx-C than in normal Ss; and (c) when gastric emptying dysfunction in Vgx-C Ss was removed by having Ss sham drink, Vgx-C and normal Ss sham drank equivalent amounts of water. Thus, disordered preabsorptive satiety caused by abnormally rapid gastric emptying of water was a factor in the decreased drinking of Vgx-C rats after cellular dehydration. Disordered satiety for ingested water could not, however, account for the abnormal latency to initiate drinking after cellular dehydration in Vgx-C rats. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cholinergic and beta-adrenergic compounds in the control of drinking behavior in the rat.

Describes a series of studies with male Wistar rats (N = 220) in which injections of a- and b-adrenergic agonists and antagonists, as well as carbachol and angiotensin II amide, were either (a) made into the lateral hypothalamus through permanently implanted cannulas or (b) administered subcutaneously to observe drinking and eating behavior. In contrast to previous reports, intrahypothalamic injections of the b-adrenergic agonist isoprenaline hydrochloride failed to elicit drinking behavior. Both carbachol and angiotensin administered to the same site and subcutaneously-administered isoprenaline induced drinking behavior. Intrahypothalamic injections of isoprenaline reduced both deprivation-induced thirst and hunger. Prior injection of the b-adrenergic blocker propranolol hydrochloride eliminated the blocking effect of isoprenaline on hunger but not thirst. Drinking induced by intrahypothalamic injections of carbachol was reduced by prior injection of isoprenaline. It is concluded that isoprenaline administered intrahypothalamically has an inhibitory effect on both hunger and thirst. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)