The exchange of C<sup>14</sup> glucose across the membrane of the human erythrocyte

Mawe, Richard C.; Hempling, H. G.

doi:10.1002/jcp.1030660110

Cited by 82 publications

(22 citation statements)

References 15 publications

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“…However, it has now proved possible to show that the exchange flux is not accelerated by an exchange process on the carrier surface as shown in eqn. (11) (Britton, 1964), and to obtain unambiguous values for the re-orientation rate ratio, p. Despite the doubt which attaches to earlier values of this ratio for the glucose carrier, it is reassuring that the value for p for the leucine carrier at 250 C (p = 3.05) is of the same order of magnitude as the values found for the glucose carriers (Levine & Stein, 1966;Mawe & Hempling, 1965 …”

Section: Discussionmentioning

confidence: 69%

The transport of L‐leucine in human erythrocytes: a new kinetic analysis

Hoare¹

1972

The Journal of Physiology

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SUMMARY1. Data on the transport of L-leucine into human erythrocytes at 250 C shows (a) that the carrier re-orientation process is rate determining, (b) that the binding of leucine to the carrier increases the rate of carrier re-orientation and (c) that the carrier is, at equilibrium, about equally distributed between the membrane surfaces at 250 C.2. These conclusions are reached through a new kinetic analysis of a simple carrier system, which involves no prior assumptions about the relative magnitudes of the rate constants, yet leads to usable kinetic equations. These equations allow the determination of the rate determining step, the calculation of the effect of bound substrate on the rate of carrier re-orientation and, in some cases, an estimate to be made of the equilibrium distribution of the carrier between the inner and outer membrane surfaces. rNTRODUCTION The transport of glucose, and, to a small extent, amino acids into the human erythrocyte has been used in establishing the basis of the present theory ofcarrier-mediated transport (reviewed, for example, by Stein, 1967). However, although complete kinetic schemes have been derived for a range of possible carrier mechanisms (Jacquez, 1961), these have always been simplified by a number of critical assumptions before being applied to experimental data. These assumptions have usually been concerned with the nature of the rate-determining step, and with the symmetry of the carrier with regard to the inner and outer surfaces of the membrane. Consequently, no definite information is available on these important features of the mechanism, and the conclusions which have been drawn are in some degree dependent on the validity of the original assumptions. In this paper, a new form of the kinetic equations for the general case is

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Section: Discussionmentioning

confidence: 69%

The transport of L‐leucine in human erythrocytes: a new kinetic analysis

Hoare¹

1972

The Journal of Physiology

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“…The observation has been made that glucose is transported out of human erythrocytes more rapidly in the presence of extracellular glucose than in its absence (34,35).…”

Section: Discussionmentioning

confidence: 99%

Hepatic organic anion uptake in the rat.

Scharschmidt¹,

Waggoner²,

Berk³

1975

J. Clin. Invest.

239

135

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A B S T R A CT(a) hepatic uptake determined by direct tissue measurement could be accurately estimated from the plasma disappearance data; (b) saturation of hepatic uptake with increasing dose was readily demonstrated for each of these three organic anions, and in each instance a plot of V versus dose took the form of a rectangular hyperbola analyzable in terms of Michaelis-Menten kinetics; (c) for BR, the saturable uptake process showed a V.a. more than 100 times the normal net transfer rate from plasma to bile; (d) hepatic uptake of BR, BSP, and ICG showed relatively selective, mutually competitive inhibition; glycocholic acid did not inhibit hepatic uptake of any of these substances; and (e) "countertransport" could be demonstrated for each of the three test substances. These data are compatible with the existence of a carrier-mediated transport process for hepatic uptake of each of these three organic anions and clarify the relationship of hepatic BR uptake to its overall transport from plasma to bile.

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“…In this method the samples were cooled rapidly from 38 to 00 C by injecting the cell suspension into nylon tubes, frozen into an ice cube. Mawe & Hempling (1965) proved that the error introduced was negligible. I8otopes.…”

Section: Methodsmentioning

confidence: 95%

Effects of hexoses and anions on the erythritol permeability of human red cells

Wieth¹

1971

The Journal of Physiology

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SUMMARY1. The effect of hexoses and of the anions chloride, thiocyanate, and salicylate on the permeability of human red cells to [14C]erythritol has been studied.2. It was confirmed that erythritol competes with glucose, mannose, and galactose for the hexose transfer system of the red cell membrane.Approximately 25 % of the erythritol influx was insensitive to the presence of hexoses or phloretin. Identical maximum degrees of inhibition were obtained with 0 3 M glucose and with phloretin (0.5 x 10-3M). In the absence of competing inhibitors the erythritol permeability, P, was 1-2 x 10-7 cm/sec at 380 C. At maximum inhibition P was 0 3 x 10-7cm/sec.3. Erythritol is able to penetrate the membrane by two pathways, only one of which is sensitive to hexoses. Both hexose-sensitive and hexoseinsensitive erythritol influx are well described by first-order diffusion kinetics. The affinity of erythritol for the hexose transfer system is very low, and the half saturation constants of hexoses can be determined from their ability to retard erythritol permeation. The following values were found for the half saturation of the transport system with hexoses at 380 C: glucose 6 mm, mannose 11 mm, and galactose 40 mM.4. Thiocyanate and salicylate reduce the hexose-sensitive fraction of erythritol influx, but the hexose-insensitive erythritol permeability is not affected when chloride is replaced by the foreign anions. This applies to the whole temperature range between 0 and 380 C, where the ionic permeabilities of red cells have been shown to be profoundly changed by thiocyanate and salicylate.

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The exchange of C¹⁴ glucose across the membrane of the human erythrocyte

Cited by 82 publications

References 15 publications

The transport of L‐leucine in human erythrocytes: a new kinetic analysis

The transport of L‐leucine in human erythrocytes: a new kinetic analysis

Hepatic organic anion uptake in the rat.

Effects of hexoses and anions on the erythritol permeability of human red cells

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The exchange of C14 glucose across the membrane of the human erythrocyte

Cited by 82 publications

References 15 publications

The transport of L‐leucine in human erythrocytes: a new kinetic analysis

The transport of L‐leucine in human erythrocytes: a new kinetic analysis

Hepatic organic anion uptake in the rat.

Effects of hexoses and anions on the erythritol permeability of human red cells

Contact Info

Product

Resources

About

The exchange of C¹⁴ glucose across the membrane of the human erythrocyte