Role of a glycocalyx on coronary arteriole permeability to proteins: evidence from enzyme treatments

2000 ◽  
Vol 278 (4) ◽  
pp. H1177-H1185 ◽  
Author(s):  
Virginia H. Huxley ◽  
Donna A. Williams
Keyword(s):  
Muscle Tone ◽  
Enzyme Treatment ◽  
Solute Flux ◽  
Miniature Swine ◽  
Solute Permeability ◽  
Endothelial Cell Surface ◽  
Porcine Serum ◽  
Before And After ◽  
Barrier Resistance ◽  
Coronary Arterioles

Whereas the glycocalyx of endothelial cells has been shown to influence solute flux from capillary microvessels, little is known about its contribution to the movement of macromolecules across the walls of other microvessels. We evaluated the hypothesis that a glycocalyx contributes resistance to protein flux measured in coronary arterioles. Apparent solute permeability ( P s) to two proteins of different size and similar charge, α-lactalbumin (α-lactalb) and porcine serum albumin (PSA), was determined in arterioles isolated from the hearts of 43 female Yucatan miniature swine. P s was assessed in arterioles with an “intact” glycocalyx under control conditions and again after suffusion with adenosine (Ado, 10− 5 M, n = 42 arterioles, N = 29 pigs). In a second set of experiments ( n = 21 arterioles, N = 21 pigs) arteriolar P s was determined before and after perfusion with enzyme (pronase or heparinase), which was used to digest the glycocalyx. P s was assessed a third time on those microvessels after exposure to Ado. Consistent with the hypothesis, P s for PSA ([Formula: see text]) and P sfor α-lactalb ([Formula: see text]) increased from basal levels following enzyme treatment. Subsequent suffusion with Ado, a significant metabolite known to alter coronary vascular smooth muscle tone and permeability, resulted in a significant reduction of basal [Formula: see text] in both untreated and enzyme-treated arterioles. Furthermore, in untreated arterioles, [Formula: see text] was unchanged by Ado suffusion, whereas Ado induced a pronounced reduction in[Formula: see text] of enzyme-treated vessels. These data demonstrate that in intact coronary arterioles an enzyme-sensitive layer, most likely at the endothelial cell surface, contributes significantly to net barrier resistance to solute flux.

scholarly journals Sexual dimorphism in the permeability response of coronary microvessels to adenosine

2005 ◽  
Vol 288 (4) ◽  
pp. H2006-H2013 ◽  
Author(s):  
Virginia H. Huxley ◽  
JianJie Wang ◽  
Stevan P. Whitt
Keyword(s):  
Sexual Dimorphism ◽  
Serum Albumin ◽  
Adult Male ◽  
Volume Regulation ◽  
Solute Flux ◽  
Male And Female ◽  
Porcine Serum ◽  
Males And Females ◽  
Gender Influences ◽  
Coronary Arterioles

Gender influences volume regulation via several mechanisms; whether these include microvascular exchange, especially in the heart, is not known. In response to adenosine (Ado), permeability ( Ps) to protein of coronary arterioles of female pigs decreases acutely. Whether Ado induces similar Ps changes in arterioles from males or whether equivalent responses occur in coronary venules of either sex has not been determined. Hypotheses that 1) basal Ps properties and 2) Ps responses to vasoactive stimuli are sex independent were evaluated from measures of Ps to two hydrophilic proteins, α-lactalbumin and porcine serum albumin (PSA), in arterioles and venules isolated from hearts of adult male and female pigs. Consistent with hypothesis 1, basal Ps values of both microvessel types were independent of sex. Contrary to hypothesis 2, Ps responses to Ado varied with sex, protein, and vessel type. Confirming earlier studies, Ado induced a ∼20% decrease in Ps to both proteins in coronary arterioles from females. In arterioles from males, Ado did not change Ps for α-lactalbumin ([Formula: see text], 3 ± 13%), whereas Ps for PSA ([Formula: see text]) decreased by 27 ± 8% ( P < 0.005). In venules from females, Ado elevated [Formula: see text] by 44 ± 20% ( P < 0.05), whereas in those from males, Ado reduced [Formula: see text] by 24 ± 5% ( P < 0.05). The variety of outcomes is consistent with transvascular protein and protein-carried solute flux being regulated by multiple sex-dependent mechanisms in the heart and provides evidence of differences in exchange homeostasis of males and females in health and, likely, disease.

scholarly journals Simulation of S-Entropy Production during the Transport of Non-Electrolyte Solutions in the Double-Membrane System

Entropy ◽  
2020 ◽  
Vol 22 (4) ◽  
pp. 463
Author(s):  
Andrzej Ślęzak ◽  
Wioletta M. Bajdur ◽  
Kornelia M. Batko ◽  
Radomir Šcurek
Keyword(s):  
Entropy Production ◽  
Transport Theory ◽  
Membrane System ◽  
Electrolyte Solutions ◽  
Solute Flux ◽  
Initial Moment ◽  
Hydraulic Permeability ◽  
Transport Parameters ◽  
Double Membrane ◽  
Solute Permeability

Using the classical Kedem–Katchalsky’ membrane transport theory, a mathematical model was developed and the original concentration volume flux (Jv), solute flux (Js) characteristics, and S-entropy production by Jv, ( ( ψ S ) J v ) and by Js ( ( ψ S ) J s ) in a double-membrane system were simulated. In this system, M1 and Mr membranes separated the l, m, and r compartments containing homogeneous solutions of one non-electrolytic substance. The compartment m consists of the infinitesimal layer of solution and its volume fulfills the condition Vm → 0. The volume of compartments l and r fulfills the condition Vl = Vr → ∞. At the initial moment, the concentrations of the solution in the cell satisfy the condition Cl < Cm < Cr. Based on this model, for fixed values of transport parameters of membranes (i.e., the reflection (σl, σr), hydraulic permeability (Lpl, Lpr), and solute permeability (ωl, ωr) coefficients), the original dependencies Cm = f(Cl − Cr), Jv = f(Cl − Cr), Js = f(Cl − Cr), ( Ψ S ) J v = f(Cl − Cr), ( Ψ S ) J s = f(Cl − Cr), Rv = f(Cl − Cr), and Rs = f(Cl − Cr) were calculated. Each of the obtained features was specially arranged as a pair of parabola, hyperbola, or other complex curves.

Effects of pharyngeal lubrication on the opening of obstructed upper airway

1992 ◽  
Vol 72 (6) ◽  
pp. 2311-2316 ◽  
Author(s):  
H. Miki ◽  
W. Hida ◽  
Y. Kikuchi ◽  
T. Chonan ◽  
M. Satoh ◽  
...  
Keyword(s):  
Hypoglossal Nerve ◽  
Muscle Tone ◽  
Upper Airway ◽  
Intraluminal Pressure ◽  
Lower Airway ◽  
Before And After ◽  
Airway Opening ◽  
Cervical Trachea ◽  
Artificial Surfactant ◽  
Stimulation Of

We examined the effect of electrical stimulation of the hypoglossal nerve and pharyngeal lubrication with artificial surfactant (Surfactant T-A) on the opening of obstructed upper airway in nine anesthetized supine dogs. The upper airway was isolated from the lower airway by transecting the cervical trachea. Upper airway obstruction was induced by applying constant negative pressures (5, 10, 20, and 30 cmH2O) on the rostral cut end of the trachea. Peripheral cut ends of the hypoglossal nerves were electrically stimulated by square-wave pulses at various frequencies from 10 to 30 Hz (0.2-ms duration, 5–7 V), and the critical stimulating frequency necessary for opening the obstructed upper airway was measured at each driving pressure before and after pharyngeal lubrication with artificial surfactant. The critical stimulation frequency for upper airway opening significantly increased as upper airway pressure became more negative and significantly decreased with lubrication of the upper airway. These findings suggest that greater muscle tone of the genioglossus is needed to open the occluded upper airway with larger negative intraluminal pressure and that lubrication of the pharyngeal mucosa with artificial surfactant facilitates reopening of the upper airway.

scholarly journals Characterization and Prebiotic Potential of Longan Juice Obtained by Enzymatic Conversion of Constituent Sucrose into Fructo-Oligosaccharides

Molecules ◽  
2018 ◽  
Vol 23 (10) ◽  
pp. 2596 ◽  
Author(s):  
Yongxia Cheng ◽  
Haibo Lan ◽  
Lei Zhao ◽  
Kai Wang ◽  
Zhuoyan Hu
Keyword(s):  
Soluble Sugar ◽  
Monosaccharide Composition ◽  
Water Soluble ◽  
Lactobacillus Delbrueckii ◽  
Soluble Solids ◽  
Enzyme Treatment ◽  
Bacteria Growth ◽  
Before And After ◽  
Soluble Polysaccharide

The prebiotic potential of longan juice obtained by a commercial Viscozyme L for conversion of constituent sucrose to fructo-oligosaccharide was investigated. The physicochemical properties and carbohydrate composition of the longan juice was evaluated before and after enzymatic treatment. The stimulation effects of the treated longan juice on probiotic bacteria growth were also studied in vitro. The results showed that total soluble solids, yield and clarity of longan juice were all significantly improved after enzyme treatment. The water-soluble polysaccharide content, including pectin, was significantly increased. Compared with the natural longan pulp, the enzyme treated juice showed a significant decrease in sucrose content. Substantial fructo-oligosaccharides including 1-kestose and nystose were synthesized after enzyme treatment. The molecular weight distribution and the monosaccharide composition of the water-soluble polysaccharide were significantly changed by enzyme treatment. The treated longan juice and its ethanol-soluble sugar fraction promoted the growth of Streptococus thermophiles, Lactobacillus acidophilus and Lactobacillus delbrueckii, showing a good potential of the treated longan juice for producing functional foods and nutraceuticals.

scholarly journals Preparation of defect free TFC FO membranes using robust and highly porous ceramic substrate

2018 ◽  
Vol 1 (4) ◽  
Author(s):  
Jincai Su ◽  
Yanyan Wei ◽  
Hui Li
Keyword(s):  
Osmotic Pressure ◽  
Interfacial Polymerization ◽  
Pure Water ◽  
Porous Ceramic ◽  
Water Flux ◽  
Solute Flux ◽  
Structural Parameter ◽  
Solute Permeability ◽  
Draw Solution ◽  
Surface Pores

In this study, robust and defect-free thin film composite (TFC) forward osmosis (FO) membranes have been successfully fabricated using ceramic hollow fibers as the substrate. Polydopamine (PDA) coating under controlled conditions is effective to reduce the surface pores of the substrate and make the substrate smooth enough for the interfacial polymerization. The pure water permeability (A), solute permeability (B) and structural parameter (S) of the resultant FO membrane are 0.854 L·m-2h-1bar-1 (LMH/Bar) 0.186 L·m-2h-1 (LMH) and 1720 µm, respectively. The water flux and reverse draw solute flux are measured using NaCl and proprietary ferric sodium citrate (FeNaCA) draw solutions at low and high osmotic pressure ranges. With increasing the osmotic pressure, higher water flux is obtained but its increase is not directly proportional to the increase in the osmotic pressure. At the membrane surface, the effect of dilutive concentration polarization is much less serious for FeNaCA draw solutions. At an osmotic pressure of 89.6 bar, the developed TFC membrane generates water fluxes of 11.5 and 30.0 LMH using NaCl and synthesized FeNaCA draw solutions. The corresponding reverse draw solute flux is 7.0 g·m-2h-1 (gMH) for NaCl draw solution but it is not detectable for FeNaCA draw solution. This means that the developed TFC FO membranes are defect free and their surface pores are at molecular level. The performance of the developed TFC FO membranes are also demonstrated for the enrichment of BSA protein.

scholarly journals Toxicity associated with ingestion of a polyacrylic acid hydrogel dog pad

2018 ◽  
Vol 30 (5) ◽  
pp. 708-714 ◽  
Author(s):  
David C. Dorman ◽  
Melanie L. Foster ◽  
Brooke Olesnevich ◽  
Brad Bolon ◽  
Aude Castel ◽  
...  
Keyword(s):  
Motor Activity ◽  
Polyacrylic Acid ◽  
Muscle Tone ◽  
Clinical Signs ◽  
High Dose ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Before And After ◽  
Acute Neurotoxicity ◽  
Disposable Diapers

Superabsorbent sodium polyacrylate polymeric hydrogels that retain large amounts of liquids are used in disposable diapers, sanitary napkins, and other applications. These polymers are generally considered “nontoxic” with acute oral median lethal doses (LD50) >5 g/kg. Despite this favorable toxicity profile, we identified a novel toxic syndrome in dogs and rats following the ingestion of a commercial dog pad composed primarily of a polyacrylic acid hydrogel. Inappropriate mentation, cerebellar ataxia, vomiting, and intention tremors were observed within 24 h after the ingestion of up to 15.7 g/kg of the hydrogel by an adult, castrated male Australian Shepherd mix. These observations prompted an experimental study in rats to further characterize the toxicity of the hydrogel. Adult, female Sprague Dawley rats ( n = 9) were assessed before and after hydrogel ingestion (2.6–19.2 g/kg over 4 h) using a functional observation battery and spontaneous motor activity. Clinical signs consistent with neurotoxicity emerged in rats as early as 2 h after the end of hydrogel exposure, including decreased activity in an open field, hunched posture, gait changes, reduced reaction to handling, decreased muscle tone, and abnormal surface righting. Hydrogel-exposed rats also had reduced motor activity when compared with pre-exposure baseline data. Rats that ingested the hydrogel did not develop nervous system lesions. These findings support the conclusion that some pet pad hydrogel products can induce acute neurotoxicity in animals under high-dose exposure conditions.

Mechanism of thrombin-induced vasodilation in human coronary arterioles

2003 ◽  
Vol 284 (4) ◽  
pp. H1080-H1086 ◽  
Author(s):  
John J. Bosnjak ◽  
Ken Terata ◽  
Hiroto Miura ◽  
Atsushi Sato ◽  
Alfred C. Nicolosi ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Right Atrial ◽  
Tetraethylammonium Chloride ◽  
Protein Activation ◽  
Protein Receptor ◽  
No Release ◽  
Before And After ◽  
Clotting Cascade ◽  
Tetrabutylammonium Chloride ◽  
Coronary Arterioles

Thrombin (Thromb), activated as part of the clotting cascade, dilates conduit arteries through an endothelial pertussis toxin (PTX)-sensitive G-protein receptor and releases nitric oxide (NO). Thromb also acts on downstream microvessels. Therefore, we examined whether Thromb dilates human coronary arterioles (HCA). HCA from right atrial appendages were constricted by 30–50% with endothelin-1. Dilation to Thromb (10−4–1 U/ml) was assessed before and after inhibitors with videomicroscopy. There was no tachyphylaxis to Thromb dilation (maximum dilation = 87.0%, ED50 = 1.49 × 10−2). Dilation to Thromb was abolished with either hirudin or denudation but was not affected by PTX. Neither N ω-nitro-l-arginine methyl ester ( n = 7), indomethacin ( n = 9),1H-[1,2,4] oxadiazolo-[4,3-a]quinoxalin-1-one ( n = 6), tetraethylammonium chloride ( n = 5), nor iberiotoxin ( n = 4) reduced dilation to Thromb. However, KCl (maximum dilation = 89 ± 5 vs. 20 ± 10%; P < 0.05; n = 7), tetrabutylammonium chloride (maximum dilation = 79 ± 7 vs. 21 ± 4%; P < 0.05; n = 5), and charybdotoxin (maximum dilation = 89 ± 4 vs. 10 ± 2%; P < 0.05; n = 4) attenuated dilation to Thromb. In contrast to animal models, Thromb-induced dilation in human arterioles is independent of Gi-protein activation and NO release. However, Thromb dilation is endothelium dependent, is maintained on consecutive applications, and involves activation of K+ channels. We speculate that an endothelium-derived hyperpolarizing factor contributes to Thromb-induced dilation in HCA.

Hypothalamus and respiratory minute volume

1960 ◽  
Vol 198 (6) ◽  
pp. 1304-1306 ◽  
Author(s):  
Edward S. Redgate
Keyword(s):  
Blood Pressure ◽  
High Frequency ◽  
Muscle Tone ◽  
Minute Volume ◽  
Reflex Pathways ◽  
Before And After ◽  
Significant Depression ◽  
Volume Decrease ◽  
Frequency Current ◽  
Respiratory Reflex

Minute volume of respiration was measured in 21 cats. Hypodermic tubing and electrodes were implanted in the hypothalamus. Minute volume of respiration was measured before and after depression of the hypothalamus by coagulation with high frequency current or by microinjection of 4% thiopental into sites in the hypothalamus. Depression of the hypothalamus was followed by a 20–30% decrease in minute volume. The results were statistically significant. Depression of the thalamus by coagulation or microinjection of thiopental was not followed by a significant change in minute volume. Intravenous injection of the amount of thiopental injected into the hypothalamus did not alter minute volume. Minute volume decrease was often associated with blood pressure and muscle tone decreases, but in several cases, minute volume decreases were independent of blood pressure and muscle tone. The evidence supports the argument that tonic discharges from the hypothalamus increase the excitability of respiratory reflex pathways and effect increased minute volume.

scholarly journals Effects of solvent and solute drag on transmembrane diffusion.

1982 ◽  
Vol 79 (3) ◽  
pp. 507-528 ◽  
Author(s):  
J T Van Bruggen ◽  
B Chalmers ◽  
M Muller
Keyword(s):  
Solute Drag ◽  
Tracer Diffusion ◽  
The Other ◽  
Solute Flux ◽  
Solvent Drag ◽  
Solution Flow ◽  
Solute Permeability ◽  
Drag Forces ◽  
Transmembrane Diffusion

The present study compares and quantitates both solvent drag and solute drag forces in a system with both heteropore and homopore membranes. It is shown that tracer solute permeability can be increased if solution flow or driver solute flux is in the direction of tracer diffusion. Either force can decrease tracer permeability if the force can decrease tracer permeability if the force is opposite to the direction of tracer diffusion. The two forces can be additive or one force may reduce the effect of the other force. In the particular system quantitated, solute drag is shown to be some 300 times more effective than solvent drag on a mole-to-mole basis. The use of a number of solute pairs on other homopore and heteropore membranes confirms the finding that the two drag forces can be analyzed or manipulated in a variety of systems.

Serotonin Syndrome: Early Management with Cyproheptadine

2001 ◽  
Vol 35 (7-8) ◽  
pp. 870-873 ◽  
Author(s):  
William W McDaniel
Keyword(s):  
Serotonin Syndrome ◽  
Muscle Tone ◽  
Symptomatic Relief ◽  
Vital Signs ◽  
Signs And Symptoms ◽  
Test Dose ◽  
Index Patient ◽  
Early Management ◽  
Rapid Reversal ◽  
Before And After

OBJECTIVE: T o report a psychiatric patient who developed serotonin syndrome after a medication overdose and whose marked mydriasis was quickly reversed by administration of cyproheptadine. This phenomenon was confirmed when other cases of serotonin syndrome were studied. METHOD: In the index patient as well as in three subsequent cases of serotonin syndrome, pupil diameter, muscle tone, mental status, and vital signs were monitored before and after a test dose of cyproheptadine as medications were discontinued and antiserotonergic therapy begun. RESULTS: In each patient, cyproheptadine produced rapid reversal of mydriasis within one hour of the initial dose. Other signs of serotonin syndrome remitted more slowly. As the signs and symptoms of serotonin syndrome remitted and pupils returned to normal size and reactiveness, cyproheptadine therapy seemed to produce mydriasis after each dose. Cessation of therapy after this point did not result in recurrence of symptoms. One patient developed serotonin syndrome twice. Two patients developed serotonin syndrome during treatment with medications that are partial serotonin antagonists (mirtazapine and nefazodone). CONCLUSIONS: Rapid reversal of mydriasis in serotonin syndrome by cyproheptadine may serve as a specific suppressive test for the condition, and possibly may add to our understanding of the syndrome. Treatment with cyproheptadine is not thought to abbreviate the illness, but provides symptomatic relief while symptoms persist.

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