Symmetry and Non-Linearity of osmotic Flow Across Rectal Cuticle of the Desert Locust

1971 ◽  
Vol 54 (2) ◽  
pp. 317-328
Author(s):  
J. E. PHILLIPS ◽  
C. BEAUMONT
Keyword(s):  
Permeability Coefficient ◽  
Rectal Wall ◽  
Tritiated Water ◽  
Diffusion Permeability ◽  
Desert Locust ◽  
Osmotic Flow ◽  
Osmotic Permeability ◽  
Single File ◽  
Flux Measurements

1. A method for measuring osmotic flow of water across rectal cuticle of the desert locust in vitro is described. 2. The osmotic permeability coefficient decreases as the average osmolality of the two bathing solutions increases, probably due to dehydration of the cuticle. This is supported by a corresponding decrease in the diffusion permeability coefficient, as measured by flux of tritiated water in the absence of osmotic flow. 3. Osmotic permeability is at least fifty times greater than diffusion permeability. This supports the hypothesis that osmotic flow occurs by bulk flow or single-file diffusion through pores. Isotopic flux measurements during net flow support this view. 4. The osmotic permeability of the cuticle differs by less than 25 % if at all, in the two directions of flow; that is, rectification or ‘valve-like’ behaviour is not significant. 5. The cuticle represents only 2.6 to 13 % of the total resistance to osmotic flow across the whole rectal wall and is not responsible for the asymmetry of the latter. 6. Application of Beament's model for water transport to the rectal wall of insects can be excluded in the case of the desert locust.

Transition of permeability properties along the descending limb of long-loop nephron

1988 ◽  
Vol 254 (3) ◽  
pp. F323-F328 ◽  
Author(s):  
M. Imai ◽  
J. Taniguchi ◽  
K. Yoshitomi
Keyword(s):  
Permeability Coefficient ◽  
Lower Portion ◽  
Reflection Coefficients ◽  
Osmotic Permeability ◽  
Functional Transition ◽  
Diffusion Voltage ◽  
Negative Diffusion

The isolated segments of the hamster descending limb of the long-loop nephron (LDL) were perfused in vitro to demonstrate the axial heterogeneity with respect to permeability properties. When a NaCl gradient from the lumen to bath was present, the lumen-negative diffusion voltage (VD) was generated in the upper portion (LDLU). When the VD was measured stepwise along the axis of tubules, the magnitude of the VD decreased in the portion within 0.5 mm before the border between the outer and inner medulla in most cases, indicating that a gradual functional transition to the lower portion (LDLL) occurs along the descending limb. The lumen-to-bath flux coefficients (K1----b) for Na+ were 14.3 +/- 3.7 X 10(-7) and 2.4 +/- 0.8 X 10(-7) cm2/s in the LDLU and LDLL, respectively. The K1----b for urea were 1.7 +/- 0.6 X 10(-7) and 7.9 +/- 4.1 X 10(-7) cm2/s, respectively. The LDLL was highly permeable to water, with osmotic permeability coefficient being 1,693 +/- 517 X 10(-9) cm2.s-1.atm-1. The reflection coefficients for NaCl and urea were not different from unity. From these observations, we conclude that the functional transition occurs along the LDL from the segment with a high Na+ permeability to that with a low Na+ permeability.

scholarly journals Diffusion and Osmotic Permeability of Ion Exchange Membrane MK-40 Using Sodium Chloride Solution

2021 ◽  
Vol 29 (4) ◽  
Author(s):  
Mohammed Qader Gubari ◽  
Haider Mohammed Zwain ◽  
Nadezda Vyacheslavovna Alekseeva
Keyword(s):  
Sodium Chloride ◽  
Cation Exchange ◽  
Permeability Coefficient ◽  
Elevated Temperatures ◽  
Diffusion Permeability ◽  
Membrane Properties ◽  
Nacl Solution ◽  
Osmotic Permeability ◽  
Exchange Membrane ◽  
Over Time

Cation exchange membrane (MK-40) is a commercial membrane with a fixed group that is an important part of the electrodialysis (ED) process. Sodium chloride (NaCl) diffusion and osmotic permeability for MK-40 was studied. A cell containing two compartments was used to analyse the properties of the MK-40 membrane fixed between them. Furthermore, the influence of temperature, NaCl concentration, and operating time on MK-40 properties was investigated. The results showed that the highest diffusion permeability coefficient of NaCl was 7.37×10-9 (m2/s), and the maximum osmotic permeability coefficient of distilled water was 43.8×10-9 (m2/s) at NaCl solution concentration of 0.1 M and 50oC. Generally, the permeability was constant beyond 60 min of operational time. Additionally, the minimum diffusion permeability coefficients of the MK-40 membrane fell by about 22% over time when the concentration of NaCl solution was 1 M at 25oC. To conclude, membrane properties in the ED process depend on the two electrodes (a cathode and an anode), without the diffusion of salts particles. Meanwhile, the most important properties of cation exchange membranes (CEMs) used in electrodialysis are increased membrane efficiency when water and salts transport decrease through CEMs, which leads to a decrease in energy consumption. Thus, the MK-40 membrane showed a good properties due to its low diffusion permeability for concentrated NaCl solution at elevated temperatures and minimum reduction in diffusion permeability of concentrated NaCl solution over time.

scholarly journals Antidiuretic Action of a Corpus Cardiacum Factor (CTSH) on Long-Term Fluid Absorption Across Locust Recta in Vitro

1984 ◽  
Vol 113 (1) ◽  
pp. 409-421 ◽  
Author(s):  
B. PROUX ◽  
J. PROUX ◽  
J. E. PHILLIPS
Keyword(s):  
Active Transport ◽  
Chloride Transport ◽  
Rectal Wall ◽  
Fluid Absorption ◽  
Corpus Cardiacum ◽  
Osmotic Permeability ◽  
Antidiuretic Action ◽  
Stimulation Of

Long-term fluid absorption (Jv) by everted rectal sacs from locusts is stimulated by both corpus cardiacum (CC) extracts and cAMP in a dosedependent manner. This hormonal antidiuretic activity (ADH) is present in both nervous and glandular lobes of CC. This distribution is similar to that of chloride transport stimulating hormone (CTSH) but not to that of other factors previously reported from this gland. As expected if ADH were due to CTSH acting on electrogenic Cl− transport, CC extracts also increased the electropotential across rectal sacs, and the stimulation of fluid absorption ceased in Cl-free salines. CC extracts also caused recta to absorb fluid against larger osmotic gradients, suggesting that the antidiuretic factor acts on the ion-dependent active transport of fluid rather than on the osmotic permeability of the rectal wall.

Water and ion handling in the rat cecum

1990 ◽  
Vol 259 (5) ◽  
pp. G786-G791 ◽  
Author(s):  
E. Escobar ◽  
C. Ibarra ◽  
E. Todisco ◽  
M. Parisi
Keyword(s):  
Permeability Coefficient ◽  
Driving Force ◽  
Water Movement ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Chemical Gradient ◽  
Osmotic Permeability ◽  
Rat Cecum ◽  
Good Agreement

The minute-by-minute net water movement (Jw) in the rat cecum was correlated with the transepithelial potential difference (PD), short-circuit current (Isc), and the unidirectional Na+, Cl-, and Rb+ fluxes, with the following results. 1) Jw was a linear function of the applied hydrostatic or osmotic transepithelial gradients (hydrostatic permeability coefficiency = 0.164 +/- 0.018 cm/s, n = 13; osmotic permeability coefficient = 0.0014 +/- 0.0002 cm/s, n = 6). 2) A fraction of this absorptive Jw (0.17 +/- 0.03 microliter.min-1.cm-2, n = 13) was independent of the presence of any osmotic, hydrostatic, or chemical gradient. 3) This fraction was Na+ dependent, associated with an amiloride-insensitive PD and net Na+ (2.37 +/- 0.68 mu eq.h-1.cm-2, n = 6) and Cl- influxes (3.45 +/- 1.46 mu eq.h-1.cm-2, n = 6), measured under short-circuit conditions. No net Rb+ movement was detected. 4) The absorptive Jw increased when HCO3- was replaced by tris(hydroxymethyl)aminomethane (Tris+) buffer or Cl- by SO4(2-). A good agreement between the observed and the expected Jw (assuming isosmotic reabsorption) was observed in the absence of HCO3-. 5) The presence of an osmotic but not a hydrostatic transepithelial gradient generated a transepithelial PD. These results show that water movement across the rat cecum in vitro is the result of a combination of hydrostatic-, osmotic-, and transport-associated transfers. Concerning this last driving force, the observed results indicate that the transport-related Jw results from the addition of an absorptive Jw, coupled to a nonelectrogenic NaCl entry, plus a secretory Jw probably coupled to HCO3- secretion.

scholarly journals Comparative Evaluation of Cleaning Efficacy of Three Different Single File Systems: An In Vitro Study

2021 ◽  
pp. 26-31
Author(s):  
Deebah Choudhary
Keyword(s):  
File Systems ◽  
In Vitro Study ◽  
Single File ◽  
Working Length ◽  
Group 3 ◽  
Group 2 ◽  
Cleaning Efficacy ◽  
Scanning Electron ◽  
Group 1

Aim: The aim of this study was to evaluate the canal cleaning efficacy of these three file systems using scanning electron microscopy. Place and Duration of Study: The study was conducted in the Department of Conservative dentistry and Endodontics, Institute of Dental Sciences Sehora, between October 2020 and December 2020. Materials and Methods: Access cavity preparation was performed on sixty extracted human mandibular premolar teeth and working length was determined. The samples were randomly divided into three groups (n=20) depending upon the file system used i.e. Group 1 (Reciproc Blue), Group 2 (Waveone Gold) and Group 3 (F360). Samples were split into two halves by creating longitudinal grooves on the buccal and lingual surfaces. The samples were sputter-coated with gold and examined under scanning electron microscope at 5000X. The dentinal wall of root canal at coronal, middle and apical thirds of each sample were evaluated for the presence of determining the canal cleanliness and then analyzed using a five-score index. Results: The results of this study revealed that Group 1 (Reciproc Blue) exhibited better cleaning efficacy than samples of Group 2 (WaveOne Gold) and Group 3 (F360) at different locations in the canal i.e. coronal, middle and apical. The mean debris present was highest in coronal area for both group 2 and group 3 i.e. 2.1 and least was seen in apical area of group 1 i.e. 0.3. (p<0.05) Conclusion: Reciproc Blue single-file showed highest cleaning efficacy followed by Waveone Gold and F360. Reciproc file also showed effective cleaning in the apical third of the canal.

Studies on Chitin Synthesis in the Desert Locust

1962 ◽  
Vol 39 (1) ◽  
pp. 129-140 ◽  
Author(s):  
D. J. CANDY ◽  
B. A. KILBY
Keyword(s):  
Schistocerca Gregaria ◽  
In Vivo Studies ◽  
Desert Locust ◽  
Uridine Diphosphate ◽  
In Vitro Experiments ◽  
Chitin Synthesis ◽  
Acetyl Coenzyme A ◽  
Phosphohexose Isomerase

1. In vivo studies on 5th instar and adult locusts revealed that chitin formation in thorax, abdomen, hind leg and wing was greatest during the first few days after moulting. 2. Wing extracts were used for in vitro experiments, and evidence was obtained for the presence of the following enzymes: hexokinase, phosphohexose isomerase, glutamine transaminase, phosphoglucosamine transacetylase, acetyl coenzyme-A synthetase, phosphoacetylglucosamine mutase and uridine diphosphate N-acetylglucosamine pyrophosphorylase. 3. The results are discussed, and a tentative scheme is presented for the biosynthesis of chitin in the wing of Schistocerca gregaria.

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