The Use of the Human Erythrocyte as a Model for Studying the Action of Diuretics on Sodium and Chloride Transport

1978 ◽  
Vol 54 (6) ◽  
pp. 679-683 ◽  
Author(s):  
B. A. Brooks ◽  
A. F. Lant
Keyword(s):  
Transport System ◽  
Human Erythrocyte ◽  
Chloride Transport ◽  
Transport Systems ◽  
Na Transport ◽  
Cl Transport ◽  
Henle's Loop ◽  
Low Concentrations ◽  
Biochemical Action ◽  
Chemical Analogue

1. The Na+ and Cl− transport systems of human erythrocytes have been compared for their sensitivities to diuretics known to act in the ascending limb of Henle's loop. In addition, chemical analogues of ‘loop’ compounds and also diuretics which act in other areas of the nephron have been examined. 2. The Na+ transport system lacks specificity with respect to inhibition by ‘loop’ diuretics and also a related chemical analogue studied at equivalent concentrations. 3. The Cl− transport system is inhibited, at low concentrations, by diuretics known to act in the ascending limb of Henle's loop. 4. Erythrocyte Cl− transport offers a useful model with which to study the biochemical action of diuretics.

Effects of arginine vasopressin on the thin ascending limb of Henle's loop of hamsters

1982 ◽  
Vol 243 (2) ◽  
pp. F167-F172 ◽  
Author(s):  
M. Imai ◽  
E. Kusano
Keyword(s):  
Adenylate Cyclase ◽  
Arginine Vasopressin ◽  
Chloride Transport ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Renal Tubules ◽  
Thick Ascending Limb ◽  
Cl Transport ◽  
Henle's Loop ◽  
Perfusion Studies

Arginine vasopressin (AVP) has been shown to stimulate active Cl transport across the medullary thick ascending limb of Henle's loop (MAL) in association with an increase in adenylate cyclase activity. To determine whether the failure to demonstrate active Cl transport across the thin ascending limb of Henle's loop (TAL) in previous in vitro perfusion studies was due to the absence of AVP in the preparation, we examined the effect of AVP on adenylate cyclase activity and Cl transport in the hamsters TAL. AVP (1 mU/ml) increased adenylate cyclase activity in the hamster TAL (20.7 +/- 5.2 control vs. 46.2 +/- 10.1 fmol . mm-1 . 30 min-1, n = 6, P less than 0.05) but not in the descending limb (27.8 +/- 7.0 control vs. 20.4 +/- 2.7, n = 4, P less than 0.05). When both MAL and TAL were perfused, a lumen-positive transepithelial voltage (Vt) was observed. The Vt was increased by adding 1 or 10 mU/ml AVP to the bath. When only the TAL was perfused, the Vt was not different from zero. Similar results were obtained in mouse renal tubules. In other experiments, AVP did not affect the diffusion potential generated when a transepithelial NaCl gradient was present. AVP or dibutyryl cAMP caused little or no change in efflux of radioactive chloride across the hamster TAL. These findings suggest that electrogenic chloride transport is not demonstrable in the TAL even in the presence of AVP. The physiologic role of AVP-sensitive adenylate cyclase in the TAL remains to be established.

Interaction between sodium and chloride transport in canine tracheal mucosa

1979 ◽  
Vol 46 (1) ◽  
pp. 111-119 ◽  
Author(s):  
F. J. Al-Bazzaz ◽  
Q. Al-Awqati
Keyword(s):  
Hormonal Regulation ◽  
Chloride Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Na Transport ◽  
Tracheal Mucosa ◽  
Electrically Conductive ◽  
Ussing Chambers ◽  
Cl Secretion ◽  
Cl Transport

Canine tracheal mucosae were dissected and mounted as flat sheets in Ussing chambers. Unidirectional isotope fluxes of 22Na and 36Cl were performed across paired mucosae from the same animal. The average spontaneous potential difference was 42 + 1.2 mV (mean +/- SE) lumen negative. The short-circuit current (SCC) 3.09 +/- 0.36 mueq/cm2.h was accounted for by a net Cl secretion of 2.46 +/- 0.26 mueq/cm2.h toward the mucosa and net Na absorption of 0.46 +/- 0.13 mueq/cm2.h toward submucosa. Removal of Cl depressed SCC but had no effect on unidirectional or net Na transport (n = 7). By contrast, removal of Na (n = 6) or the addition of ouabain (n = 7) abolished net Cl secretion and greatly reduced SCC. Theophylline (n = 6) added to the submucosal bath no significant effect on Na transport but stimulated SCC and Cl secretion, suggesting hormonal regulation of Cl transport. The results suggest that the active transport of Na and Cl in this epithelium occur by electrically conductive pathways, i.e., the transport is “electrogenic.” Further it appears that Na transport is independent of the presence of Cl but that Cl transport depends on some parameter of active Na transport.

scholarly journals An explanation of the asymmetric binding of sugars to the human erythrocyte sugar-transport systems

1973 ◽  
Vol 135 (3) ◽  
pp. 539-541 ◽  
Author(s):  
J. E. G. Barnett ◽  
G. D. Holman ◽  
K. A. Munday
Keyword(s):  
Transport System ◽  
Human Erythrocyte ◽  
Sugar Transport ◽  
Transport Systems

6-O-Alkyl-d-galactoses competitively inhibit the erythrocyte sugar-transport system when added to the outside of the cells, but not to the inside. n-Propyl β-d-glucopyranoside competitively inhibits the system on the inside of the cells, but not on the outside. A model for sugar transport is proposed.

Chloride transport inhibition by piretanide and MK-196 in bullfrog corneal epithelium

1981 ◽  
Vol 240 (1) ◽  
pp. F25-F29
Author(s):  
O. A. Candia ◽  
H. F. Schoen ◽  
L. Low ◽  
S. M. Podos
Keyword(s):  
Corneal Epithelium ◽  
Electrical Resistance ◽  
Chloride Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Na Transport ◽  
Cl Transport ◽  
Apical Side ◽  
Diuretic Agents ◽  
Cl Permeability

Two new diuretic agents, piretanide and MK-196, inhibited short-circuit current (SCC) across the isolated frog corneal epithelium. The effect is explained as an inhibition of active Cl transport. A definite decrease in SCC and an increase in electrical resistance was observed with both diuretics in concentrations as low as 10(-6) M. Piretanide, at 10(-4) M, reduced the SCC by 90%, reduced th unidirectional forward Cl flux from 0.60 to 0.28 mueq x h-1 x cm-2, and increased the resistance by 60%. There was no effect on the Cl backflux. At 10(-4) M, MK-196 reduced the SCC by 83% and increased the resistance by 72%, from 1.68 to 2.91 k omega x cm2. Replacement of Cl by SO4 in the bathing solutions resulted in a larger increase in resistance, from 1.68 to 3.80 k omega x cm2. The diuretics had no effect on active Na transport across the corneal epithelium. After the permeability of the apical side was increased by amphotericin B, the drugs could not inhibit the Cl-originated SCC. These results suggest that piretanide and MK-196 selectively inhibit active Cl transport in the cornea by blocking Cl permeability of the apical side of the epithelial cells.

Source and distribution of factors in locust nervous system which stimulate rectal Cl− transport

1985 ◽  
Vol 63 (1) ◽  
pp. 37-41 ◽  
Author(s):  
J. Proux ◽  
B. Proux ◽  
J. Phillips
Keyword(s):  
Chloride Transport ◽  
Short Circuit ◽  
Active Form ◽  
Short Circuit Current ◽  
Neurosecretory Cells ◽  
Neuroendocrine Cells ◽  
Response Curves ◽  
Ussing Chambers ◽  
Cl Transport ◽  
Low Concentrations

Corpus cardiacum (CC) of locusts contains a potent stimulant of rectal Cl transport, i.e., chloride transport stimulating hormone (CTSH). Extracts of other locust tissues which contain neuroendocrine cells were assayed for their ability to stimulate Cl-dependent, short-circuit current (Isc) across recta mounted in Ussing chambers. Dose–response curves indicated that only brain (particularly the pars intercerebralis, PI) contained substantial stimulatory activity, but this was still at very low concentrations compared with CTSH activity in CC. Destruction of either the PI or the nerve tract from PI to CC (i.e., NCC I) reduced CTSH levels in the CC. In contrast, destruction of lateral neurosecretory cells (NSCs) of the brain had no effect. The results suggest that CTSH is synthesized in NSCs of the PI and is transported down NCC I to the CC where it may mature to a more active form.

Effect of Ca2+ on Cl- transport in thin ascending limb of Henle's loop

1988 ◽  
Vol 254 (2) ◽  
pp. F232-F239 ◽  
Author(s):  
Y. Kondo ◽  
K. Yoshitomi ◽  
M. Imai
Keyword(s):  
Small Reduction ◽  
Na Transport ◽  
Ph Titration ◽  
Cl Transport ◽  
Titration Curves ◽  
Henle's Loop ◽  
Diffusion Voltage ◽  
Bathing Fluid ◽  
Cl Permeability

Effects of ambient Ca2+ concentration on Cl- transport across the thin ascending limb of Henle's loop (TAL) were examined by the in vitro microperfusion technique. When Ca2+ concentration in the bathing fluid was decreased from 1.5 mM to nominally 0 mM at 37 degrees C, the relative permeability of Cl- to Na+ (PCl/PNa) estimated from the NaCl diffusion voltage changed from 2.44 +/- 0.20 to 1.27 +/- 0.16 (n = 7, P less than 0.01). When Ca2+ concentration of the luminal fluid was reduced, PCl/PNa was unchanged. When Ca2+ concentration in the bathing fluid was changed from 4.5 to nominally 0 mM, the lumen-to-bath flux coefficient for 36Cl (K36Cl(l----b)) was decreased, whereas the value for 22Na was unchanged, indicating that the reduction of Ca2+ concentration in the bathing fluid selectively inhibits Cl- transport without affecting Na+ transport. By contrast, at 23 degrees C, the elimination of Ca2+ from the bathing fluid caused only a small reduction of PCl/PNa. Although at 23 degrees C acidification of the bathing fluid caused only little or no decrease in Cl- permeability, the elimination of Ca2+ from the bathing fluid under acid pH markedly suppressed the (K36Cl(l----b)) (10(-7) cm2/s). The pH titration curves of relative Cl- permeability examined at three different Ca2+ concentrations at 37 degrees C revealed that the interaction between proton and Ca2+ was noncompetitive. Addition of quin 2-AM, which reduced intracellular Ca2+ concentration, to the bath caused an irreversible suppression of Cl- permeability, suggesting that the decrease in intracellular Ca2+ concentration also inhibits the Cl- transport across the TAL.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Evidence for two asymmetric conformational states in the human erythrocyte sugar-transport system

1975 ◽  
Vol 145 (3) ◽  
pp. 417-429 ◽  
Author(s):  
J E Barnett ◽  
G D Holman ◽  
R A Chalkley ◽  
K A Munday
Keyword(s):  
Glucose Transport ◽  
Transport System ◽  
Human Erythrocyte ◽  
Partition Coefficients ◽  
External Medium ◽  
Sugar Transport ◽  
Conformational States ◽  
Glucose Transport System ◽  
Oil Water

6-O-methyl-, 6-O-propyl-, 6-O-pentyl- and 6-O-benzyl-D-galactose, and 6-O-methyl-, 6-O-propyl- and 6-O-pentyl-D-glucose inhibit the glucose-transport system of the human erythrocyte when added to the external medium. Penetration of 6-O-methyl-D-galactose is inhibited by D-glucose, suggesting that it is transported by the glucose-transport system, but the longer-chain 6-O-alkyl-D-galactoses penetrate by a slower D-glucose-insensitive route at rates proportional to their olive oil/water partition coefficients. 6-O-n-Propyl-D-glucose and 6-O-n-propyl-D-galactose do not significantly inhibit L-sorbose entry or D-glucose exit when present only on the inside of the cells whereas propyl-beta-D-glucopyranoside, which also penetrates the membrane slowly by a glucose-insensitive route, only inhibits L-sorbose entry or D-glucose exit when present inside the cells, and not when on the outside. The 6-O-alkyl-D-galactoses, like the other nontransported C-4 and C-6 derivatives, maltose and 4,6-O-ethylidene-D-glucose, protect against fluorodinitrobenzene inactivation, whereas propyl beta-D-glucopyranoside stimulates the inactivation. Of the transported sugars tested, those modified at C-1, C-2 and C-3 enhance fluorodinitrobenzene inactivation, where those modified at C-4 and C-6 do not, but are inert or protect against inactivation. An asymmetric mechanism is proposed with two conformational states in which the sugar binds to the transport system so that C-4 and C-6 are in contact with the solvent on the outside and C-1 is in contact with the solvent on the inside of the cell. It is suggested that fluorodinitrobenzene reacts with the form of the transport system that binds sugars at the inner side of the membrane. An Appendix describes the theoretical basis of the experimental methods used for the determination of kinetic constants for non-permeating inhibitors.

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