Electrical characteristics of snake distal tubules: studies of I-V relationships

1980 ◽  
Vol 239 (5) ◽  
pp. F402-F411 ◽  
Author(s):  
B. M. Koeppen ◽  
K. W. Beyenbach ◽  
W. H. Dantzler ◽  
S. I. Helman
Keyword(s):  
Chemical Potential ◽  
Distal Tubule ◽  
Ringer Solution ◽  
Open Circuit ◽  
Transepithelial Resistance ◽  
Constant Current ◽  
Toad Urinary Bladder ◽  
Current Voltage ◽  
Distal Tubules

Distal tubules of Thamnophis spp. were perfused in vitro with Ringer solution containing either 16 or 150 mM Na and bathed with 150 mM Na Ringer. Current-voltage relationships were obtained by injecting pulses of constant current, Io, into the tubule lumen and recording changes in voltage, delta Vo, at the proximal end of the perfused tubule segment. The Io-Vo plots showed a distinct break at a voltage E1 (approximately 85 mV) that was greater than the open-circuit voltage, VToc, and similar to values of ENa, the transepithelial driving force for Na transport estimated by other methods. The resistance of the shunt pathway, Rs, was estimated from the values of the transepithelial resistance after luminal addition of 10(-5) M amiloride, which caused a rapid fall of the VToc to 0 mV with concurrent increases of the transepithelial resistance. These estimates of Rs were the same as the values of E1/I1 obtained from the Io-Vo plots. The VToc, RT, and Rs were independent of the bath [Na] and were not influenced by the addition of amiloride to the bath. As in frog skin and toad urinary bladder, the ENa and Rs of the snake distal tubule can be estimated from studies of their Io-Vo plots, and the E1 appears to be independent of the transepithelial chemical potential for Na.

Mechanism of acidification along cortical distal tubule of the rat

1994 ◽  
Vol 266 (2) ◽  
pp. F218-F226 ◽  
Author(s):  
R. Fernandez ◽  
M. J. Lopes ◽  
R. F. de Lira ◽  
W. F. Dantas ◽  
E. J. Cragoe Junior ◽  
...  
Keyword(s):  
Channel Blocker ◽  
Exchange Resin ◽  
Rat Kidney ◽  
Specific Inhibitor ◽  
Distal Tubule ◽  
Ringer Solution ◽  
Na Channel ◽  
Bafilomycin A1 ◽  
Bicarbonate Reabsorption ◽  
Distal Tubules

The cellular mechanism of luminal acidification (bicarbonate reabsorption) was studied in cortical distal tubules of rat kidney. The stopped-flow microperfusion technique was applied to early distal (ED) and late distal (LD) segments, perfused with bicarbonate Ringer solution to which specific inhibitors were added, to measure bicarbonate reabsorption [HCO3 flux (JHCO3)]. pH and transepithelial potential difference (Vt) were recorded by double-barreled H+ exchange resin/reference (1 M KCl) electrodes. Amiloride increased stationary pH and reduced Vt in both early and late segments. Hexamethylene-amiloride (HMA), a specific Na(+)-H+ exchange blocker, reduced JHCO3 in both segments (ED by 43.6 and LD by 40.3%) without affecting Vt. Benzamil, an Na(+)-channel blocker, reduced Vt by 75.9 in ED and 74.9% in LD but had no significant effect on acidification in both segments. The specific inhibitor of H(+)-ATPase, bafilomycin A1, inhibited LD JHCO3 at a concentration of 2 x 10(-7) M by 49%, but ED was inhibited by 24% only at 2 x 10(-6) M. Sch-28080, an inhibitor of gastric H(+)-K(+)-ATPase, reduced JHCO3 by 35% in LD of K(+)-depleted rats but not in control rats and had no effect on ED. These data indicate that, in ED, bicarbonate reabsorption is mediated mostly by Na(+)-H+ exchange. In LD, there is evidence for contribution of Na(+)-H+ exchange, vacuolar H(+)-ATPase, and H(+)-K(+)-ATPase (in K(+)-depleted rats) to bicarbonate reabsorption.

Release of cyclic AMP by toad urinary bladder

1975 ◽  
Vol 228 (3) ◽  
pp. 954-958 ◽  
Author(s):  
S Urakabe ◽  
JS Handler ◽  
J Orloff
Keyword(s):  
Epithelial Cells ◽  
Urinary Bladder ◽  
Cyclic Amp ◽  
Cell Membrane ◽  
Water Permeability ◽  
Ringer Solution ◽  
Mucosal Surface ◽  
Toad Urinary Bladder ◽  
Solution Bathing

Cyclic AMP accumulates in the Ringer solution bathing the toad urinary bladder in vitro. At least 4 times more cyclic AMP is released into the solution bathing the serosal surface than into the solution bathing the mucosal surface. Most of the cyclic AMP originates in the epithelial cells rather than the stroma. Vasopressin increased the content of cyclic AMP in the epithelial cells and increases the amount of cyclic AMP in the Ringer solution. Since there is not an increase in medium cyclic AMP when cell cyclic AMP levels are increased by theophylline, it is suggested that theophylline may reduce the permeability of the cell membrane to cyclic AMP. Finally, it is demonstrated that 10 mM NaF increase the amount of cyclic AMP in the epithelial cells and in the solution bathing the bladder, but block the effect of vasopressin on water permeability, presumably at a step subsequent to the formation of cyclic AMP.

Novel Micro-Photodiodes for Retina Stimulation

2000 ◽  
Vol 609 ◽  
Author(s):  
M. Rojahn ◽  
M.B. Schubert
Keyword(s):  
Amorphous Silicon ◽  
Ganglion Cells ◽  
Light Exposure ◽  
Open Circuit ◽  
In Vitro Tests ◽  
Buffer Solution ◽  
Long Term Stability ◽  
Current Voltage

ABSTRACTWe present a new design of micro-photodiodes for in-vitro tests to electrically stimulate the ganglion cells of chicken and rat retinae upon light exposure of the photodiodes. Based on amorphous silicon, our laterally series connected double-stacked micro-photodiodes provide an open circuit voltage of 2.3 volts. Photolithographic steps as well as etching procedures for patterning the back contact, the amorphous silicon layers and the front contact are described. We analyse current- voltage-measurements performed with direct contact of the metal needles of a micro-positioning system to the device's electrodes. In order to test the performance of an individual micro-photodiode in an electrolyte environment, the stimulation electrode of the device is also contacted with a micro-droplet of buffer solution. Further improvement is needed, mainly addressing the problem of long-term stability of the device in electrolyte environments.

scholarly journals Rab-GAP TBC1D4 (AS160) is dispensable for the renal control of sodium and water homeostasis but regulates GLUT4 in mouse kidney

2015 ◽  
Vol 309 (9) ◽  
pp. F779-F790 ◽  
Author(s):  
Marianna Di Chiara ◽  
Bob Glaudemans ◽  
Dominique Loffing-Cueni ◽  
Alex Odermatt ◽  
Hadi Al-Hasani ◽  
...  
Keyword(s):  
Glucose Uptake ◽  
Glucose Transporter ◽  
Insulin Response ◽  
Physiological Role ◽  
Distal Tubule ◽  
Rab Gtpase ◽  
Thick Ascending Limb ◽  
Water Restriction ◽  
Distal Tubules

The Rab GTPase-activating protein TBC1D4 (AS160) controls trafficking of the glucose transporter GLUT4 in adipocytes and skeletal muscle cells. TBC1D4 is also highly abundant in the renal distal tubule, although its role in this tubule is so far unknown. In vitro studies suggest that it is involved in the regulation of renal transporters and channels such as the epithelial sodium channel (ENaC), aquaporin-2 (AQP2), and the Na+-K+-ATPase. To assess the physiological role of TBC1D4 in the kidney, wild-type (TBC1D4+/+) and TBC1D4-deficient (TBC1D4−/−) mice were studied. Unexpectedly, neither under standard nor under challenging conditions (low Na+/high K+, water restriction) did TBC1D4−/−mice show any difference in urinary Na+and K+excretion, urine osmolarity, plasma ion and aldosterone levels, and blood pressure compared with TBC1D4+/+mice. Also, immunoblotting did not reveal any change in the abundance of major renal sodium- and water-transporting proteins [Na-K-2Cl cotransporter (NKCC2) NKCC2, NaCl cotransporter (NCC), ENaC, AQP2, and the Na+-K+-ATPase]. However, the abundance of GLUT4, which colocalizes with TBC1D4 along the distal nephron of TBC1D4+/+mice, was lower in whole kidney lysates of TBC1D4−/−mice than in TBC1D4+/+mice. Likewise, primary thick ascending limb (TAL) cells isolated from TBC1D4−/−mice showed an increased basal glucose uptake and an abrogated insulin response compared with TAL cells from TBC1D4+/+mice. Thus, TBC1D4 is dispensable for the regulation of renal Na+and water transport, but may play a role for GLUT4-mediated basolateral glucose uptake in distal tubules. The latter may contribute to the known anaerobic glycolytic capacity of distal tubules during renal ischemia.

scholarly journals Cellular actions of thiazide diuretics in the distal tubule.

1990 ◽  
Vol 1 (5) ◽  
pp. 832-836
Author(s):  
B A Stanton
Keyword(s):  
Apical Membrane ◽  
Basolateral Membrane ◽  
Distal Tubule ◽  
Thiazide Diuretics ◽  
Exchange Inhibitor ◽  
Disulphonic Acid ◽  
Tubule Cells ◽  
Distal Tubules ◽  
Tubule Fluid

Thiazide diuretics inhibit electroneutral NaCl reabsorption across the distal tubule of the salamander, Amphiuma, and hyperpolarize the basolateral membrane voltage (Vbl) of distal tubule cells. The objective of this study was to determine whether thiazides hyperpolarize Vbl by reducing intracellular Cl- activity (Acl). To this end, distal tubules were perfused in vitro, and electrophysiological techniques were used to measure Acl and Vbl. Hydrochlorothiazide in tubular fluid reduced ACl from 17.0 to 12.6 mM and hyperpolarized Vbl by 16 mV. Reduction of Cl- in tubular fluid from 84 to 8 mM also decreased Acl from 16.1 to 9.9 mM and hyperpolarized Vbl by 12 mV. Because a previous study suggested that electroneutral NaCl reabsorption is mediated by Na+/H(+)-Cl-/HCO3- exchangers in the apical membrane, the Cl-/HCO3- exchange inhibitor, 4,4-diisothiocyanostilbene-2-2-disulphonic acid (DIDS) was added to tubule fluid. DIDS reduced Acl from 15.0 to 11.6 and hyperpolarized Vbl by 10 mV. DIDS and hydrochlorothiazide were not additive, inhibition of Na+/H+ exchange by amiloride (10(-3) M) and Na+ replacement with N-methyl-D-glucamine also reduced Acl from 17.4 to 12.9 and hyperpolarized Vbl by 16 mV. The hyperpolarization of Vbl in each experiment is referable to the fall in Acl. These data show that thiazide diuretics regulate ACl and that the hyperpolarization of Vbl is referable to the thiazide-induced reduction of Acl.

Na+-dependent H+ and Cl- transport in in vitro frog gastric mucosa

1980 ◽  
Vol 238 (5) ◽  
pp. G403-G413 ◽  
Author(s):  
T. E. Machen ◽  
W. L. McLennan
Keyword(s):  
Time Course ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Ringer Solution ◽  
Open Circuit ◽  
Cl Transport ◽  
Coupled Process ◽  
Separate System ◽  
Energy Dependent

Na+ dependency of H+ and Cl- transport in resting and stimulated gastric mucosae was investigated. We measured transepithelial potential difference (PD), short-circuit current (Isc), conductance, H+ secretion (JH), and unidirectional fluxes of 36Cl- (muscosal (m) to serosal (s), JClm leads to s and JCLs leads to m) during Isc conditions in Ussing-type chambers. Resting tissues: Na+-free serosal solution (choline replacement), but not mucosal, Ringer solution caused PD and Isc to decrease to zero with a time course identical to that observed with Cl--free solutions. Conductance also decreased by more than 50%. Isc = JCLs leads to m--JCLm leads to 8 = JClnet during control ([Na+] = 105 mM), and Na+-free conditions. When [Na+] = 50 mM (choline replacement) Isc (=JClnet) was reduced by approximately 25%; when K+ replaced Na+, Isc (=JClnet) was reduced by approximately 65%. The dependence of Isc on [Na+] (choline replacement) was sigmoidal indicating that there may be two sites at which Na+ activates Cl- secretion. Plots of 1/Isc vs. 1/[Cl-] with different [NA+] indicated, that the affinity of the Cl- "carrier" may be affected by [Na+]. stimulated tissues: Na+-free (choline replacement) solutions caused PD, Isc, and JClnet all to decrease to zero but sometimes Na+-containing mucosal solution caused JH to increase back to 50% of control, whereas Isc increased by only 16%. Na+-free effects were not reversed by 1 mM dibutyryl cAMP plus 0.1 mM isobutyl methylxanthine in the serosal solution. As [Na+] was increased, Isc (sigmoidal) and JH (monotonic) both increased. K+ replacement of Na+ caused a larger decrease in Isc than when choline was used; JH remained constant if [Na+] greater than or equal to mM. We have proposed that the energy-dependent step for active Cl- transport occurs at the serosal membrane in a Na+-coupled process. Cl- that accompanies JH during open-circuit conditions may utilize a separate system.

Luminal Na concentration and the electrical properties of the snake distal tubule

1980 ◽  
Vol 239 (5) ◽  
pp. F412-F419 ◽  
Author(s):  
K. W. Beyenbach ◽  
B. M. Koeppen ◽  
W. H. Dantzler ◽  
S. I. Helman
Keyword(s):  
Electrical Properties ◽  
Driving Force ◽  
Open Circuit Voltage ◽  
Series Resistance ◽  
Short Circuit ◽  
Distal Tubule ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Shunt Resistance ◽  
Distal Tubules

In previous studies of isolated perfused distal tubules of Thamnophis spp., elevation of luminal [Na] from 16 to 150 mM resulted in a transient hyperpolarization of the open-circuit voltage, VToc. To characterize further this response, studies were done to examine the concurrent changes of the transepithelial resistance, RT. After elevation of luminal [Na] from 16 to 150 mM. the VToc increased sharply from a mean of 38.5 to 61.2 mV and the RT decreased from a mean of 22.3 to 15.8 k omega x cm. Thereafter, the VToc declined slowly below control values, and the RT increased well above control values. The short-circuit current calculated as VToc/RT changed in parallel with the VToc, increasing at first (from 1.8 to 4.1 microA/cm) and then falling to about 0.2 microA/cm. Luminal addition of 10(-5) M amiloride caused th VToc leads to 0 and the RT to increase during control and all phases of the transient. On the assumption that RT during amiloride perfusion is the same as the shunt resistance, Rs, the values of the transepithelial driving force, ENa, and its series resistance, RNa, were calculated. An analysis of the data in this way indicated that the principal changes in the epithelium could be attributed to alterations of the RNa and not the ENa or Rs.

Growth Kinetics of Quantum Size ZnO Particles

1998 ◽  
Vol 536 ◽  
Author(s):  
E. M. Wong ◽  
J. E. Bonevich ◽  
P. C. Searson
Keyword(s):  
Growth Kinetics ◽  
Ostwald Ripening ◽  
Chemical Potential ◽  
Colloidal Suspensions ◽  
Green Emission ◽  
Blue Shift ◽  
Constant Current ◽  
Mass Model ◽  
Zno Particles ◽  
Kinetics Of

AbstractColloidal chemistry techniques were used to synthesize ZnO particles in the nanometer size regime. The particle aging kinetics were determined by monitoring the optical band edge absorption and using the effective mass model to approximate the particle size as a function of time. We show that the growth kinetics of the ZnO particles follow the Lifshitz, Slyozov, Wagner theory for Ostwald ripening. In this model, the higher curvature and hence chemical potential of smaller particles provides a driving force for dissolution. The larger particles continue to grow by diffusion limited transport of species dissolved in solution. Thin films were fabricated by constant current electrophoretic deposition (EPD) of the ZnO quantum particles from these colloidal suspensions. All the films exhibited a blue shift relative to the characteristic green emission associated with bulk ZnO. The optical characteristics of the particles in the colloidal suspensions were found to translate to the films.

OSMOTIC INHIBITION OF THE NATRIFERIC RESPONSE OF THE TOAD URINARY BLADDER TO VASOPRESSIN

1975 ◽  
Vol 67 (1) ◽  
pp. 119-125
Author(s):  
P. J. BENTLEY
Keyword(s):  
Urinary Bladder ◽  
Water Movement ◽  
Short Circuit ◽  
Electrical Potential ◽  
Short Circuit Current ◽  
Toad Bladder ◽  
Toad Urinary Bladder ◽  
Electrical Potential Difference ◽  
Osmotic Gradient

SUMMARY The electrical potential difference and short-circuit current (scc, reflecting active transmural sodium transport) across the toad urinary bladder in vitro was unaffected by the presence of hypo-osmotic solutions bathing the mucosal (urinary) surface, providing that the transmural flow of water was small. Vasopressin increased the scc across the toad bladder (the natriferic response), but this stimulation was considerably reduced in the presence of a hypo-osmotic solution on the mucosal side, conditions under which water transfer across the membrane was also increased. This inhibition of the natriferic response did not depend on the direction of the water movement, for if the osmotic gradient was the opposite way to that which normally occurs, the response to vasopressin was still reduced. The natriferic response to cyclic AMP was also inhibited in the presence of an osmotic gradient. Aldosterone increased the scc and Na+ transport across the toad bladder but this response was not changed when an osmotic gradient was present. The physiological implications of these observations and the possible mechanisms involved are discussed.

scholarly journals Online State-of-Charge Estimation Based on the Gas–Liquid Dynamics Model for Li(NiMnCo)O2 Battery

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 324
Author(s):  
Haobin Jiang ◽  
Xijia Chen ◽  
Yifu Liu ◽  
Qian Zhao ◽  
Huanhuan Li ◽  
...  
Keyword(s):  
Stress Test ◽  
Robustness Analysis ◽  
Open Circuit ◽  
Combined Cycle ◽  
State Of Charge ◽  
Constant Current ◽  
Estimation Accuracy ◽  
Accurate Estimation ◽  
Battery Management System ◽  
Liquid Dynamics

Accurately estimating the online state-of-charge (SOC) of the battery is one of the crucial issues of the battery management system. In this paper, the gas–liquid dynamics (GLD) battery model with direct temperature input is selected to model Li(NiMnCo)O2 battery. The extended Kalman Filter (EKF) algorithm is elaborated to couple the offline model and online model to achieve the goal of quickly eliminating initial errors in the online SOC estimation. An implementation of the hybrid pulse power characterization test is performed to identify the offline parameters and determine the open-circuit voltage vs. SOC curve. Apart from the standard cycles including Constant Current cycle, Federal Urban Driving Schedule cycle, Urban Dynamometer Driving Schedule cycle and Dynamic Stress Test cycle, a combined cycle is constructed for experimental validation. Furthermore, the study of the effect of sampling time on estimation accuracy and the robustness analysis of the initial value are carried out. The results demonstrate that the proposed method realizes the accurate estimation of SOC with a maximum mean absolute error at 0.50% in five working conditions and shows strong robustness against the sparse sampling and input error.

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