Hyperosmotic Saline Research Articles

Temperature changes and chondrocyte death during drilling in a bovine cartilage model and chondroprotection by modified irrigation solutions.

Drilling into cartilage/bone is often required for orthopaedic surgery. While drilling into bone has been studied, the response of cartilage has received little attention. We have measured cartilage and drill bit temperatures during drilling and quantified the zone of chondrocyte death (ZCD) around the hole in the presence/absence of irrigation solutions. Drilling was performed using a 1.5-mm orthopaedic drill bit applied to bovine metatarsophalangeal joints and temperatures recorded by infrared camera. Osteochondral explants were then incubated with 5-chloromethylfluorescein diacetate (CMFDA) and propidium iodide (PI) to label living/dead chondrocytes respectively. The width of the ZCD was quantified by confocal laser scanning microscopy (CLSM) and image analysis. Without irrigation, the ZCD following drilling for two seconds was 135 ± 15μm and this increased (>fourfold, P < 0.001) with five seconds of drilling. Irrigation reduced the ZCD following drilling for both two and five seconds (P < 0.05, P < 0.001 respectively) to the same level (approx. 60μm). Without irrigation, drill bit and cartilage temperature increased rapidly to >265 and 119°C respectively, whereas the camera saturated at >282°C during drilling for five seconds. With irrigation, the drill bit temperature was significantly reduced during drilling for two and five seconds (approx. 90°C) with negligible change in cartilage temperature. Drilling while irrigating with hyperosmotic saline (600mOsm) reduced (P < 0.01) the ZCD compared to saline, whereas chondrocyte death was increased (P < 0.01) by Ca(2+) saline (5mM). Reducing temperature during drilling by irrigation markedly suppressed, but did not abolish chondrocyte death. Optimising the irrigation solution by raising osmolarity and reducing Ca(2+) content significantly reduced chondrocyte death during drilling and may be clinically beneficial.

Understanding the cellular mechanism for inhaled hyperosmotic saline therapy for patients with cystic fibrosis. Focus on “Effect of apical hyperosmotic sodium challenge and amiloride on sodium transport in human bronchial epithelial cells from cystic fibrosis donors”

since the first clinical trials on inhaled hyperosmotic saline therapy (HS) in cystic fibrosis (CF) patients ([3][1], [9][2]), HS has proven to substantially improve a number of critical measures of lung function and, thus, is now considered a first-line therapy for these patients ([2][3]). One

Impaired muscarinic type 3 (M3) receptor/PKC and PKA pathways in islets from MSG-obese rats

Monosodium glutamate-obese rats are glucose intolerant and insulin resistant. Their pancreatic islets secrete more insulin at increasing glucose concentrations, despite the possible imbalance in the autonomic nervous system of these rats. Here, we investigate the involvement of the cholinergic/protein kinase (PK)-C and PKA pathways in MSG β-cell function. Male newborn Wistar rats received a subcutaneous injection of MSG (4 g/kg body weight (BW)) or hyperosmotic saline solution during the first 5 days of life. At 90 days of life, plasma parameters, islet static insulin secretion and protein expression were analyzed. Monosodium glutamate rats presented lower body weight and decreased nasoanal length, but had higher body fat depots, glucose intolerance, hyperinsulinemia and hypertrigliceridemia. Their pancreatic islets secreted more insulin in the presence of increasing glucose concentrations with no modifications in the islet-protein content of the glucose-sensing proteins: the glucose transporter (GLUT)-2 and glycokinase. However, MSG islets presented a lower secretory capacity at 40 mM K(+) (P < 0.05). The MSG group also released less insulin in response to 100 μM carbachol, 10 μM forskolin and 1 mM 3-isobutyl-1-methyl-xantine (P < 0.05, P < 0.0001 and P < 0.01). These effects may be associated with a the decrease of 46 % in the acetylcholine muscarinic type 3 (M3) receptor, and a reduction of 64 % in PKCα and 36 % in PKAα protein expressions in MSG islets. Our data suggest that MSG islets, whilst showing a compensatory increase in glucose-induced insulin release, demonstrate decreased islet M3/PKC and adenylate cyclase/PKA activation, possibly predisposing these prediabetic rodents to the early development of β-cell dysfunction.

Evaluación del cloruro de sodio, eugenol y zeolita en el confinamiento de Ancistrus triradiatus

The use of sodium chloride (1 and 2 g/L), eugenol (0.1 and 0.5 mg/L), and zeolite (clinoptilolite, 7 g/L for 12 h and 10 g/L for 48 h of confinement), and also mixtures of salt plus eugenol (1 g/L and 0.5 mg/L, respectively) and eugenol plus zeolite (0.5 mg/L and 7 or 10 g/L, respectively) were evaluated in the confinement of Ancistrus triradiatus for 12 and 48h. Water parameters as concentration of dissolved oxygen, pH, temperature, conductivity, and concentrations of total ammonia, non-ionized ammonia and nitrite were monitored. The blood glucose concentration was measured before the confinement started and at 0, 24, and 48 hours after the confinement period finished. A stress resistance test was conducted right after the confinement time was completed by exposing the fish to a hyperosmotic saline solution for one hour, recording the number of fish that maintained the swimming axis at intervals of 5 minutes. The mortality at the end of both confinement periods (12 and 48 hours), and its cumulative percentage rate during the following 7 days were also recorded. The use of sodium chloride 1 and 2 g/L in confinement times of 12 h, and 1 g/L in confinement time of 48 hours increased the resistance to confinement-induced stress, and reduced mortality of the animals. The use of eugenol and zeolite did not improve the response to the stress, nor contribute to the reduction of mortality of the animals, while exposure to the mixtures of salt plus eugenol and eugenol plus zeolite increased the mortality so they are not recommended in the confinement of A. triradiatus.

抗利尿ホルモン不適合分泌症候群を呈したFisher症候群と咽頭・頸部・上腕型Guillain-Barré症候群の合併例

A 69-year-old woman complained of diplopia and truncal titubation after upper respiratory infection. She presented with mydriasis and external opthalmoplegia of bilateral eyes, ataxia, hyporeflexia and cervical-brachial muscle weakness. The protein abnormally increased (49 mg/dl) in the cerebrospinal fluid, and the serum anti-GQ1b and anti-GT1a IgG antibodies were positive. The blood sodium level was 128 mmol/l indicating hyponatremia. She had low plasma osmolarity (251 mOsm/kg), high urine osmolarity (357 mOsm/kg) and high urine sodium level (129 mmol/l), while the blood level of antidiuretic hormone was not able to be measured. She was diagnosed to have Fisher syndrome (FS), pharyngeal-cervical-brachial variant of Guillain-Barré syndrome (PCB) and syndrome of inappropriate secretion of antidiuretic hormone (SIADH). The hyponatremia improved with hyperosmotic saline infusion and restriction of water intake. Intravenous immunoglobulin therapy (IVIg) was effective only for ataxia, but the other symptoms mostly remained unchanged for a month. The serum anti-GQ1b IgG antibody was still positive even after one month. We performed high-dose intravenous steroid-pulse therapy. Then the mydriasis, external opthalmoplegia and cervical-brachial muscle weakness were immediately improved. This was a rare case of FS and PCB complicated with SIADH. IVIg, not steroid therapy, is generally chosen for FS since FS is considered as a variant of Guillain-Barré syndrome and steroid is not effective for Guillain-Barré syndrome as was proven by double-blind study. We suppose that the combined therapy of IVIg and steroid would be effective in patients with complicated symptoms and multiple antibodies.

CARDIOVASCULAR EFFECTS AFTER GLUTAMATE MICROINJECTION INTO THE RVLM OF MSG OBESE CONSCIOUS RATS

Obesity is a precursor condition of several diseases, among them hypertension. The sympathoexcitatory neurons of the rostral ventrolateral medulla (RVLM), which directly innervate sympathetic preganglionic neurons in the intermediolateral cell columns of the spinal cord, are a possible target for cardiovascular modulation by obesity, and glutamatergic neurotransmission has an important role. Thus, the aim of this study was to determine the effect of glutamate microinjection into the RVLM in control and MSG obese rats. Obesity was induced by intradermal administration of 4 mg/g of monosodium glutamate (MSG) or hyperosmotic saline (control = CTR) in the first 5 days of life in male Wistar rats. At 90 days old, the animals were submitted to guide cannulae implantation to the RVLM for unilateral microinjection of L‐glutamate (5 nmol/100 nl) in conscious state for recording for mean arterial pressure (MAP) and heart rate (HR). There was no difference in MAP and HR at baseline among the experimental groups (CTR: 112 ± 2 mmHg, 362 ± 14 bpm; MSG: 106 ± 3 mmHg, 389 ± 13 bpm). Unilateral microinjection of l‐glutamate produced an increase in MAP in CTR and MSG groups, however, the magnitude of this response was higher in obese rats (CTR: 44 ± 3; MSG: 56 ± 2, p=0,02). The excitation of the RVLM with glutamate decreased HR to levels that were not statistically different between groups (CTR: −26 ± 19 bpm; MSG: −45 ± 37 bpm). The present results suggest that MSG obese rats may have elevated sympathetic nerve activity originated from the activity of RVLM neurons.

Capacitance increases of dissociated tilapia prolactin cells in response to hyposmotic and depolarizing stimuli

Prolactin (PRL) is the major hormonal mediator of adaptation to hyposmotic conditions. In tilapia ( Oreochromis mossambicus), PRL cells are segregated to the rostral pars distalis of the anterior pituitary facilitating the nearly pure culture of dissociated PRL cells. Membrane capacitance ( C m) was recorded at 1 Hz or higher for tens of minutes as a surrogate monitor of PRL secretion by exocytosis from cells under perforated patch clamp. The study compares secretory responses to trains of depolarizing clamps (100 at 2.5 Hz, from −70 to +10 mV for 100 ms) to the physiological stimulus, exposure to hyposmotic medium, here a switch from 350 to 300 mOsm saline ([Ca 2+] 15 mM). Two-thirds of cells tested with each stimulus responded. In response to depolarizing clamps, C m increased linearly at an average rate of 7.2 fF/s. The increase was also linear in response to hyposmotic perfusion, but the average rate was 0.68 fF/s. Response to depolarization was reversibly blocked in Ca 2+-omitted saline, or in saline with 30 μM Cd 2+. It was unaffected by 0.1 μM tetrodotoxin. By contrast, responses were reduced but not absent during perfusion of hyposmotic saline with Ca 2+-omitted; 30 μM Cd 2+ appeared to enhance the hyposmotic response. BAPTA-AM eliminated responses to both stimuli, confirming that secretion was dependent on increases of intracellular [Ca 2+]. Together with previous observations from this laboratory of [Ca 2+] i with simultaneous collection and immunoassay of perfusate for PRL, we conclude that depolarization and hyposmotic stimuli initiate secretion by independent mechanisms.

Hyperosmolarity protects chondrocytes from mechanical injury in human articular cartilage

The aim of this study was to determine whether exposure of human articular cartilage to hyperosmotic saline (0.9%, 600 mOsm) reduces in situ chondrocyte death following a standardised mechanical injury produced by a scalpel cut compared with the same assault and exposure to normal saline (0.9%, 285 mOsm). Human cartilage explants were exposed to normal (control) and hyperosmotic 0.9% saline solutions for five minutes before the mechanical injury to allow in situ chondrocytes to respond to the altered osmotic environment, and incubated for a further 2.5 hours in the same solutions following the mechanical injury. Using confocal laser scanning microscopy, we identified a sixfold (p = 0.04) decrease in chondrocyte death following mechanical injury in the superficial zone of human articular cartilage exposed to hyperosmotic saline compared with normal saline. These data suggest that increasing the osmolarity of joint irrigation solutions used during open and arthroscopic articular surgery may reduce chondrocyte death from surgical injury and could promote integrative cartilage repair.

Effects of vagotomy, splanchnic nerve lesion, and fluorocitrate on the transmission of acute hyperosmotic stress signals to the supraoptic nucleus

The response to hyperosmotic stresses in the abdominal cavity is regulated, in part, by vasopressin (VP)-secreting neurons in the supraoptic nucleus (SON). How osmotic stress signals are transmitted to the brain is incompletely understood, and whether the transmission routes for osmotic stress signals differ between acute and chronic stresses is unknown. Here we investigated the role of the vagus, splanchnic nerves, and astrocytes in the SON in transducing acute hyperosmotic-stress signals from the abdominal cavity. We found that acute administration of hyperosmotic saline triggered the activation of neurons as well as astrocytes in the SON and the adjoining ventral glia limitans (SON-VGL). Severing the subdiaphragmatic vagal nerve (SDV) prevented the normal response of cells in the SON to HS treatment and attenuated the release of VP into the bloodstream. Lesioning the splanchnic nerves (SNL) diminished HS-induced release of VP, but to a much lesser extent than SDV. Furthermore, SNL did not significantly affect the up-regulation of Fos in SON neurons or the up-regulation of Fos and GFAP in SON and SON-VGL astrocytes that normally occurred in response to HS and did not affect HS-induced expansion of the SON-VGL. Inhibiting astrocytes with fluorocitrate (FCA) prevented the response of the SON to HS and attenuated the release of VP, similarly to SDV surgery. These results suggest that the vagus is the principle route for the transmission of hyperosmotic signals to the brain and that astrocytes in the SON region are necessary for the activation of SON neurons and the release of VP into the bloodstream.

Role of hypo-osmotic saline drops in ocular comfort during contact lens wear

To determine whether hypo-osmotic saline drops can improve contact lens associated discomfort and dryness by decreasing contact lens osmolality. Fifteen symptomatic subjects wore Lotrafilcon A lenses bilaterally for 6h on two different days. According to randomisation, hypo-osmotic (280mmol/kg) or hyper-osmotic (380mmol/kg) saline drops were applied four times during each day and ocular symptoms, tear film and contact lens parameters, and contact lens osmolality were assessed. Sixty percent of the subjects preferred the hypo-osmotic saline drops, compared to 33%, who preferred the hyper-osmotic ones. Subjects experienced significantly less dryness and lens awareness with hypo-osmotic saline drops compared to hyper-osmotic ones (p<0.05). Using the hypo-osmotic drops, there was a trend for decreased contact lens osmolality from 379 to 343mmol/kg (p=0.06). There were no differences in lipid layer, non-invasive tear film break-up time, lens surface wettability, lens water content after wear, lens movement on eye or ocular staining and indentation between saline drops (all p>0.05). Interestingly, the difference in contact lens osmolality between drops did not reflect the osmolality difference between the two saline drops. Hypo-osmotic saline drops were preferred by a greater number of subjects and contact lens osmolality tended to be lower with the use of hypo-osmotic saline. Hypo-osmotic drops have the potential to decrease contact lens osmolality which in turn may help improve ocular comfort. This has possible impact on the practitioners' choice of the lens rewetting drop recommended and the design of future lens rewetting drops.

Hyperhydration In Resting Trained Males

Hyperhydration of euhydrated resting athletes using hyperosmotic saline solutions is rarely studied. Hyperosmotic saline solutions are often studied for rehydration. PURPOSE: To compare the retention of 3 hyperosmotic saline solutions and ability to increase total body water of resting athletes. METHODS: Nine aerobically trained, male subjects; age 21 + 1.5 yr, 177 +5.8 cm, 74 +8.2 kg, and 14 +2.9 % body fat, gave informed concent to participate in a repeated-measures, single-blinded, cross-over design study. Subjects were randomly assigned to group A,B,or C. Treatment order was; A,B,C; B,C,A, or C,A,B. Trials were 3hr conducted > 3da apart. Subjects followed behavioral/dietary guidelines 72hr before testing. Urine density (1.015-1.040) verified euhydration status. The base solution for treatments made from a 50% diluted sports drink, contained; 100mg Na, 90mg K, and 7g CHO. NaCl was added to make 3 saline solutions: S30-30 mmol/L (0.91g NaCl) (the full strength sports drink): S60-60 mmol/L (1.8g NaCl), and S90- 90 mmol/L (3.6g NaCl). Treatment volume (1.4±0.14L) was determined as 3% of subjects estimated total body water. Urine output, urine density, plasma osmolality, Hct, and Hb were measured hourly. Subjects remained seated except to empty bladders. RESULTS:Table 1CONCLUSION: Drinking 1.4L of a 30mmol/L Na solution (equal to a sports drink with the most Na) produced a net loss of body water. Drinking 1.4L of the 60 and 90mmol/L solutions allowed subjects to retain 25% (341mL) and 35% (479mL), and may be ergogenic for some athletes.

Dissecting and Recording from The C. Elegans Neuromuscular Junction

Neurotransmission is the process by which neurons transfer information via chemical signals to their post-synaptic targets, on a rapid time scale. This complex process requires the coordinated activity of many pre- and post-synaptic proteins to ensure appropriate synaptic connectivity, conduction of electrical signals, targeting and priming of secretory vesicles, calcium sensing, vesicle fusion, localization and function of postsynaptic receptors and finally, recycling mechanisms. As neuroscientists it is our goal to elucidate which proteins function in each of these steps and understand their mechanisms of action. Electrophysiological recordings from synapses provide a quantifiable read out of the underlying electrical events that occur during synaptic transmission. By combining this technique with the powerful array of molecular and genetic tools available to manipulate synaptic proteins in C. elegans, we can analyze the resulting functional changes in synaptic transmission. The C. elegans NMJs formed between motor neurons and body wall muscles control locomotion, therefore, mutants with uncoordinated locomotory phenotypes (known as unc s) often perturb synaptic transmission at these synapses 1. Since unc mutants are maintained on a rich supply of a bacterial food source, they remain viable as long as they retain some pharyngeal pumping ability to ingest food. This, together with the fact that C. elegans exist as hermaphrodites, allows them to pass on mutant progeny without the need for elaborate mating behaviors. These attributes, coupled with our recent ability to record from the worms NMJs 2,3,7 make this an excellent model organism in which to address precisely how unc mutants impact neurotransmission. The dissection method involves immobilizing adult worms using a cyanoacrylic glue in order to make an incision in the worm cuticle exposing the NMJs. Since C. elegans adults are only 1 mm in length the dissection is performed with the use of a dissecting microscope and requires excellent hand-eye coordination. NMJ recordings are made by whole-cell voltage clamping individual body wall muscle cells and neurotransmitter release can be evoked using a variety of stimulation protocols including electrical stimulation, light-activated channel-rhodopsin-mediated depolarization 4 and hyperosmotic saline, all of which will be briefly described.

Dissecting and Recording from The C. Elegans Neuromuscular Junction

Neurotransmission is the process by which neurons transfer information via chemical signals to their post-synaptic targets, on a rapid time scale. This complex process requires the coordinated activity of many pre- and post-synaptic proteins to ensure appropriate synaptic connectivity, conduction of electrical signals, targeting and priming of secretory vesicles, calcium sensing, vesicle fusion, localization and function of postsynaptic receptors and finally, recycling mechanisms. As neuroscientists it is our goal to elucidate which proteins function in each of these steps and understand their mechanisms of action. Electrophysiological recordings from synapses provide a quantifiable read out of the underlying electrical events that occur during synaptic transmission. By combining this technique with the powerful array of molecular and genetic tools available to manipulate synaptic proteins in C. elegans, we can analyze the resulting functional changes in synaptic transmission. The C. elegans NMJs formed between motor neurons and body wall muscles control locomotion, therefore, mutants with uncoordinated locomotory phenotypes (known as unc s) often perturb synaptic transmission at these synapses 1. Since unc mutants are maintained on a rich supply of a bacterial food source, they remain viable as long as they retain some pharyngeal pumping ability to ingest food. This, together with the fact that C. elegans exist as hermaphrodites, allows them to pass on mutant progeny without the need for elaborate mating behaviors. These attributes, coupled with our recent ability to record from the worms NMJs 2,3,7 make this an excellent model organism in which to address precisely how unc mutants impact neurotransmission. The dissection method involves immobilizing adult worms using a cyanoacrylic glue in order to make an incision in the worm cuticle exposing the NMJs. Since C. elegans adults are only 1 mm in length the dissection is performed with the use of a dissecting microscope and requires excellent hand-eye coordination. NMJ recordings are made by whole-cell voltage clamping individual body wall muscle cells and neurotransmitter release can be evoked using a variety of stimulation protocols including electrical stimulation, light-activated channel-rhodopsin-mediated depolarization 4 and hyperosmotic saline, all of which will be briefly described.

Comparison of Exhaled Breath Condensate and Sputum Induced by Hyperosmotic Saline Inhalation as Indicators of Airway Inflammation Associated with Bronchial Asthma

RATIONALE: Testing of sputum induced by hypertonic saline inhalation has been established as a useful indicator of airway inflammation associated with bronchial asthma. Although exhaled breath condensate(EBC) can be collected simply and noninvasively, it is unclear whether it can serve as a valid indicator of airway inflammation.

Altered renal sodium handling in spontaneously hypertensive rats (SHR) after hypertonic saline intracerebroventricular injection: Role of renal nerves

The mechanism by which blood pressure rises in the SHR strain remains to be elucidated. Also, there is a surprising lack of experimental data on the natriuretic mechanisms induced by intracerebroventricular (ICV) injection of hyperosmotic saline (HoS) in SHR. In normotensive animals ICV injection of HoS causes coordinated responses including natriuresis and inhibition of renal sympathetic nerve activity. In the present study, we hypothesized that presumable blunting of the sympathoinhibitory response to centrally injected HoS may contribute to a lack of suppression of efferent renal nerve outflow in SHR. To test this hypothesis, the present study evaluates the influence of renal denervation after central HoS injection at increasing concentration on urinary sodium handling in SHR compared with age-matched normotensive WKy rats. The study confirmed previous data showing pronounced natriuretic response to centrally HoS stimuli but also demonstrated that the creatinine clearance ( C Cr) and fractional sodium excretion responses diminished as graded NaCl concentrations were increased in WKy rats but not in SHR. In SHR, increased FE Na obtained by central administration of 0.90 M NaCl was produced by increases in proximal (FEP Na) and post-proximal fractional urinary sodium rejection without changes in C Cr, indicating a direct tubular effect. Renal denervation caused significant antinatriuresis by decreased C Cr and increased FEP Na reabsorption in WKy but not in SHR. This study suggests that natriuresis observed only after higher centrally HoS stimuli with a rightward shift of dose–response curve provides evidence of a down-regulation of target organ responsiveness of periventricular areas of genetic hypertensive rats.

Decreased gastric mechanodetection, but preserved gastric emptying, in CCK-1 receptor-deficient OLETF rats

Obese CCK-1 receptor-lacking Otsuka Long Evans Tokushima fatty (OLETF) rats are hyperphagic relative to control, nonmutant Long Evans Tokushima Otsuka (LETO) rats. This study sought to assess whether the overeating observed in OLETF rats is associated with changes in gastric emptying rates or detection of gastric volume. We performed experiments in both 12- and 29-wk-old OLETF and LETO rats to address possible alterations in gastric functions during the development of increased body weight and blood glucose abnormalities in OLETF rats. Gastric emptying of a 5-g solid chow test meal was not significantly different between strains at either 1, 2, or 4 h postmeal. When rats with ad libitum access to chow were tested, there were no significant differences in gastric emptying between strains at any time period despite OLETF rats consuming significantly more chow than LETO rats. Similar to solid food, 5-min gastric emptying of a 5-ml isosmotic and hyperosmotic saline or glucose load was not significantly different between strains. When the stomach was distended with a 15-ml semisolid chow load, there was no significance difference in emptying at either 1 or 2 h. No significant differences in gastric emptying were detected between 12- and 29-wk-old rats under any conditions. Both young and old OLETF rats, however, reduced sham intake significantly less compared with LETO rats during a brief period of gastric distension by 5- or 10-ml balloon inflation. Finally, OLETF rats showed decreased Fos expression in the nucleus of the solitary tract relative to LETO rats after an 8-ml gastric distension. These findings demonstrate that OLETF rats do not express deficits in controlling gastric emptying rates; however, they exhibit decreased behavioral and vagal responsiveness to gastric distension that may contribute to the increased meal size in these animals.

Osmoregulation and tissue water regulation in the freshwater red crab Dilocarcinus pagei (Crustacea, Decapoda), and the effect of waterborne inorganic lead

Inorganic lead has been measured in high concentrations in certain streams in Brazil. This study has evaluated the osmoregulatory effects of lead on the native freshwater red crab Dilocarcinus pagei. In order to probe its osmoregulatory and tissue volume regulatory capabilities and how it would be affected by lead, the crab has been submitted to individual and combined salt and chemical stresses (Pb 2+). Male crabs were exposed for 10 days to either: (1) control (freshwater, FW), (2) brackish water of salinity 15 (BW), (3) inorganic lead in freshwater (FWPb), and (4) inorganic lead in brackish water (BWPb), 2.7 mgPb/L. In vivo, whole crabs lost weight transiently when exposed to Pb 2+, both in FW and in BW. Haemolymph osmolality and ion concentrations increased and remained elevated upon exposure of crabs to BW, with or without Pb 2+, showing a trend to hyper-conformation. In vitro, muscle weight decreased in isosmotic conditions upon exposure to Pb 2+. Na +, Cl −, and ninhydrin positive substances (NPS) were increased in muscle exposed to hyperosmotic saline, well above what would be expected from simple efflux of water, suggesting a partial regulatory volume increase (RVI) capacity. This partial RVI involves the Na +, K +, 2Cl −-cotransporter and the Na +/H + exchanger on Na + and Cl − uptake, as judged from further decreases in muscle weight in the presence of the respective inhibitors. A breakdown of proteins into NPS seems to follow the uptake of inorganic ions. Pb 2+ has affected water and ion movements in D. pagei both in the whole animal and in the isolated tissue. This study has highlighted the relevance of evaluating tissue volume regulation in aquatic animals confronted with metal polluted waters.

(Artigo 11 publicado v.28 n.2) Resposta glicogenolítica à agonistas adrenérgicos no fígado de ratos tratados com glutamato monossódico (MSG)

Administration of MSG to neonate rats causes lesions in the arcuate nucleus (AN), followed by a syndrome of neuroendocrine dysfunction characterized by obesity and decreased sympathetic activity. The aim of the present investigation was to examine the responses of hepatic glycogenolysis to α- and β-adrenergic agonists in rats’ treatment with MSG. Male Wistar rats received subcutaneous injections of MSG (4 mg g-1 body weight) or hyperosmotic saline (controls) during five days after birth. Ninety days after treatment, the livers of the MSG or controls rats were perfused in situ with epinephryne and α- and β-adrenergic agonists. Epinephryne, Isoproterenol and phenylephrine increased glycogenolysis in the MSG-treated rats, compared to the controls (50 ± 2.8 Vs 17 ± 0.89 μmol min-1 g-1 of liver, p < 0.0001; 64 ± 0.15 Vs 37 ± 0.39, p < 0.0001; 35 ± 2.48 Vs 27 ± 0.98, p < 0.05, respectively). Results indicated that the lesion in the AN increased glycogen catabolism to adrenergic agonists, possibly, due to the reduced activity of the sympathetic-adrenal axis

Control of renal endothelin release by medullary osmolarity

Exposure of renal tubular epithelial cells to high Na+ concentrations or hyperosmotic solutions enhances endothelin-1 (ET-1) production and release in vitro. Whilst providing a plausible mechanism for the increased urinary ET-1 excretion observed during high salt intake, it is not known whether infusion of hyperosmotic saline into the renal medulla would produce a similar effect in vivo. Therefore we tested the hypothesis that acute renal medullary interstitial infusion of a hyperosmotic NaCl solution will enhance urinary excretion of ET-1 in anesthetized rats. Isosmotic saline (NaCl at 284 mOsmol/kg H2O; 0.5 ml/h) was infused into the medullary interstitium of the left kidney during a 1 h equilibration period and 30 min baseline period, followed by either isosmotic or hyperosmotic NaCl (1714 mOsmol/kg H2O) for two further 30 min periods. Compared to isosmotic NaCl, infusion of hyperosmotic NaCl into the renal medulla significantly increased the rate of ET-1 excretion in the urine (P<0.05; from 0.30±0.02 to 0.49±0.03 fmol/min), increased urine flow (P<0.05) and increased the rate of Na+ excretion (P<0.05) without affecting mean arterial pressure. To determine whether the stimulus for ET-1 release was osmolarity per se or NaCl specifically, the experiment was repeated in separate groups of rats using mannitol rather than NaCl. Compared to an isosmotic mannitol solution (300 mOsmol/kg H2O), infusion of hyperosmotic mannitol (1820 mOsmol/kg H2O) significantly increased the rate of ET-1 excretion (P<0.05; from 0.54±0.03 to 0.94±0.12 fmol/min). Thus exposure of the renal medulla to hyperosmotic concentrations of NaCl stimulates renal ET-1 release in vivo. High osmolarity, rather than NaCl concentration per se, appears to act as the stimulus for this effect, consistent with the hypothesis that medullary osmolarity is an important regulator of renal medullary endothelin synthesis.

Hyperosmolar Saline Is a Proinflammatory Stress on the Mouse Ocular Surface

To investigate whether hyperosmolar stress stimulates production of inflammatory mediators and activates the mitogen-activated protein kinase (MAPK) signaling pathways, c-jun n-terminal kinases (JNKs), extracellular-regulated kinases (ERKs), and p38 on the mouse ocular surface. 129SvEv/CD-1 mixed mice were treated with a balanced salt solution (BSS) (305 mOsM) or a hyperosmotic saline solution (HOSS) (500 mOsM). Untreated age-matched mice were used as controls. The concentrations of interleukin 1beta (IL-1beta) and tumor necrosis factor alpha (TNF-alpha) were measured by enzyme-linked immunosorbent assay. Gelatinase activity was determined by in situ zymography. Corneal and conjunctival epithelia were lysed for Western blot with MAPK antibodies or used for semiquantitative reverse transcription and polymerase chain reaction and gene array. Compared with age-matched controls and mice treated with BSS, the concentration of IL-1beta in tear fluid washings and the concentrations of IL-1beta and TNF-alpha and gelatinolytic activity in the corneal and conjunctival epithelia were significantly increased in mice treated with HOSS for 2 days. The expressions of IL-1beta, TNF-alpha, and matrix metalloproteinase 9 (MMP-9) messenger RNA by the corneal and conjunctival epithelia were also notably stimulated in mice treated with HOSS. The levels of phosphorylated JNK1/2, ERK1/2, and p38 MAPKs in the corneal and conjunctival epithelia were slightly increased in mice treated with BSS, but markedly increased in mice treated with HOSS. These results show that the hyperosmolarity stimulates expression and production of IL-1beta, TNF-alpha, and MMP-9 and activates JNK, ERK, and p38 MAPK signaling pathways on the mouse ocular surface. These findings suggest that hyperosmolar stress, as it may occur in dry eye, promotes ocular surface inflammation.