The effect of temperature on the competitive inhibition of glucose transfer in human erythrocytes by phenolphthalein, phloretin and stilboestrol

Forsling, Mary L.; Widdas, W. F.

doi:10.1113/jphysiol.1968.sp008423

Cited by 16 publications

(4 citation statements)

References 11 publications

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“…Alternatively, the lack of inhibition may be attributed to the lower temperature used for trout kinetic measurements. Such temperature sensitivity of glucose transport inhibitors has previously been described (29). Thus the three-kinetic trout system was further characterized by genomic and gene expression analysis.…”

Section: Three-kinetic Slc5a-associated Glucose Absorption In Troutmentioning

confidence: 75%

Intestinal electrogenic sodium-dependent glucose absorption in tilapia and trout reveal species differences inSLC5A-associated kinetic segmental segregation

Subramaniam

Weber

Loewen

2019

American Journal of Physiology-Regulatory, Integrative and Comp

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Electrogenic sodium-dependent glucose transport along the length of the intestine was compared between the omnivorous Nile tilapia ( Oreochromis niloticus) and the carnivorous rainbow trout ( Oncorhynchus mykiss) in Ussing chambers. In tilapia, a high-affinity, high-capacity kinetic system accounted for the transport throughout the proximal intestine, midintestine, and hindgut segments. Similar dapagliflozin and phloridzin dihydrate inhibition across all segments support this homogenous high-affinity, high-capacity system throughout the tilapia intestine. Genomic and gene expression analysis supported findings by identifying 10 of the known 12 SLC5A family members, with homogeneous expression throughout the segments with dominant expression of sodium-glucose cotransporter 1 (SGLT1; SLC5A1) and sodium-myoinositol cotransporter 2 (SMIT2; SLC5A11). In contrast, trout’s electrogenic sodium-dependent glucose absorption was 20–35 times lower and segregated into three significantly different kinetic systems found in different anatomical segments: a high-affinity, low-capacity system in the pyloric ceca; a super-high-affinity, low-capacity system in the midgut; and a low-affinity, low-capacity system in the hindgut. Genomic and gene expression analysis found 5 of the known 12 SLC5A family members with dominant expression of SGLT1 ( SLC5A1), sodium-glucose cotransporter 2 (SGLT2; SLC5A2), and SMIT2 ( SLC5A11) in the pyloric ceca, and only SGLT1 ( SLC5A1) in the midgut, accounting for differences in kinetics between the two. The hindgut presented a low-affinity, low-capacity system partially attributed to a decrease in SGLT1 ( SLC5A1). Overall, the omnivorous tilapia had a higher electrogenic glucose absorption than the carnivorous trout, represented with different kinetic systems and a greater expression and number of SLC5A orthologs. Fish differ from mammals, having hindgut electrogenic glucose absorption and segment specific transport kinetics.

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Section: Three-kinetic Slc5a-associated Glucose Absorption In Troutmentioning

confidence: 75%

Intestinal electrogenic sodium-dependent glucose absorption in tilapia and trout reveal species differences inSLC5A-associated kinetic segmental segregation

Subramaniam

Weber

Loewen

2019

American Journal of Physiology-Regulatory, Integrative and Comp

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“…The phlorizin was solubilized in ethanol, and 100 μl was then added to the 8 ml incubation bath to achieve a concentration of 0.2 mM. Phloretin was used to inhibit GLUT2 activity at a dosage (1 mM) used previously (24, 32-33) and was also solubilized in ethanol and added to the incubation bath in 100 μl aliquots to achieve a concentration of 1 mM. Vehicle experiments using 100 μl of ethanol in the glucose test solution had been conducted previously and shown to cause no effect on transporter-mediated glucose uptake (24).…”

Section: Designmentioning

confidence: 99%

Mechanisms of Ileal Adaptation for Glucose Absorption after Proximal-Based Small Bowel Resection

Iqbal

Qandeel

Zheng

et al. 2008

Journal of Gastrointestinal Surgery

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INTRODUCTION The hexose transmembrane transporters SGLT1 and GLUT2 are present in low quantities in ileum where little glucose absorption occurs normally; however, glucose uptake in ileum is highly adaptable after small bowel resection. HYPOTHESIS Ileal adaptability for glucose absorption after jejunal resection is mediated predominately by upregulation of GLUT2. METHODS Rats underwent 70%, proximal-based jejunoileal resection. Transporter-mediated glucose uptake was measured in proximal and distal remnant ileum 1 and 4 wk postoperatively (n=6 rats, each) and in corresponding ileal segments in control and 1 wk sham laparotomy rats (n=6, each) without and with selective inhibitors of SGLT1 and GLUT2. In separate groups of rats (n=6, each), protein (Western blots), mRNA (RT-PCR), and villus height (histomorphology) were measured. RESULTS After 70% proximal intestinal resection, there was no dramatic change in protein or mRNA expression per cell of either SGLT1 or GLUT2, but median glucose uptake (nmol/cm/min) increased markedly from 52 (range, 28-63) in controls to 118 (range, 80-171) at 1 wk, and 203 (range, 93-248) at 4 wk (p≤0.04 each) correlating with change in villus height (p≤0.03). CONCLUSIONS Ileal adaptation for glucose transport occurs through cellular proliferation (hyperplasia) and not through cellular upregulation of glucose transporters.

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“…2). However, the half-saturation concentration for a competitive inhibitor is given by = CI(50°O)/(1 + CG/IG), (1) where C (50%) is the concentration of inhibitor reducing the glucose exit rate to 50 % of its uninhibited value, CG is the concentration of glucose in the outside medium and OG the half-saturation constant for glucose at the same temperature (Forsling & Widdas, 1968). Correcting for the outside glucose concentration (0.7 mm due to the added cell suspension) the halfsaturation constant for ethylidene glucose was 5 mM.…”

Section: Inhibition Of Glucose Exitmentioning

confidence: 99%

The permeation of human red cells by 4, 6‐O‐ethylidene‐α‐D‐glucopyranose (ethylidene glucose)

Baker¹,

Widdas²

1973

The Journal of Physiology

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SUMMARY1. The glucose derivative 4,6-0-ethylidene-ax-D-glucopyranose (ethylidene glucose) was found to inhibit glucose exit competitively but its penetration into human red cells was unaffected by glucose in the medium.2. In penetrating red cells ethylidene glucose followed diffusion type kinetics without any evidence of saturation up to 360 mm. Besides its penetration being unaffected by glucose, 105 M phloretin, which powerfully inhibits the facilitated transfer of hexoses, did not inhibit penetration.3. Red cells incubated with 1-fluoro-2,4-dinitrobenzene (FDNB) until glucose exit was reduced by 95 % showed no slowing of penetration by ethylidene glucose. 4. The potentiation of the development of FDNB inhibition by sugars in the incubating medium was absent when ethylidene glucose was used and there was a slight protective action. Cells pre-incubated with 76 mm ethylidene glucose did not show an uphill transfer from 4 mM-[14C]glucose in the outside medium in contrast to cells pre-incubated in 76 mm glucose or in 76 mm 3-0-methyl glucose.5. The possibility that ethylidene glucose penetrated human red cells by simple diffusion was supported by its penetration of guinea-pig red cells at similar rates, by the occurrence of osmotic haemolysis in isosmotic solutions which was unaffected by copper ions and by the relatively high ether/water partition of the compound.

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The effect of temperature on the competitive inhibition of glucose transfer in human erythrocytes by phenolphthalein, phloretin and stilboestrol

Cited by 16 publications

References 11 publications

Intestinal electrogenic sodium-dependent glucose absorption in tilapia and trout reveal species differences inSLC5A-associated kinetic segmental segregation

Intestinal electrogenic sodium-dependent glucose absorption in tilapia and trout reveal species differences inSLC5A-associated kinetic segmental segregation

Mechanisms of Ileal Adaptation for Glucose Absorption after Proximal-Based Small Bowel Resection

The permeation of human red cells by 4, 6‐O‐ethylidene‐α‐D‐glucopyranose (ethylidene glucose)

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