Membrane Fluidity Is Different in Intact Erythrocytes and Ghost Membranes

Tong, Pc; Thomas, T.H.; Wilkinson, Robert W.

doi:10.1006/bmmb.1994.1044

Cited by 6 publications

(8 citation statements)

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“…1% packed cell volume with 2 2 10 ÿ 6 mol L ÿ 1 DPH or TMA-DPH as we have described previously [11]. 1% packed cell volume with 2 2 10 ÿ 6 mol L ÿ 1 DPH or TMA-DPH as we have described previously [11].…”

Section: Methodsmentioning

confidence: 94%

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Erythrocyte membrane fluidity in adult polycystic kidney disease: difference between intact cells and ghost membranes

Vareesangthip¹,

Thomas²,

Tong

et al. 1996

Eur J Clin Investigation

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In adult polycystic kidney disease (APCKD) the cytoskeleton of renal tubular cells is abnormal. In erythrocytes the cytoskeleton affects the fluidity of membrane lipids. The authors determined fluorescence anisotropy in intact erythrocytes and erythrocyte ghosts in 12 APCKD patients and 12 normal subjects. In APCKD whole erythrocytes had a much lower core-region anisotropy, which indicated higher membrane fluidity than normal (mean 0 center dot 175 vs. 0 center dot 224, P < 0 center dot 01). This abnormality was not detected in erythrocyte ghosts, which suggests that preparation of ghosts altered membrane lipid organization. This could be directly due to ghosting or secondary to the loss of cytoskeletal effects, which may be abnormal in APCKD.

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Section: Methodsmentioning

confidence: 94%

“…4 with 0 . 67 mg mL ÿ 1 membrane protein and 2 2 10 ÿ 6 mol L ÿ 1 DPH or TMA-DPH as we have described previously [11].…”

Section: Methodsmentioning

confidence: 99%

Erythrocyte membrane fluidity in adult polycystic kidney disease: difference between intact cells and ghost membranes

Vareesangthip¹,

Thomas²,

Tong

et al. 1996

Eur J Clin Investigation

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“…The details of the assay used to measure anisotropy are described in detail in a previous report from our group [17]. Briefly erythrocytes were first washed with isotonic phosphate buffered saline and fluorescence anisotropy was measured in a 3 ml aliquot of a 0.1 % packed cell volume suspension of cells.…”

Section: Methodsmentioning

confidence: 99%

“…It has since been demonstrated that the process of ghosting disrupts the lipid bilayer, reducing anisotropy, possibly by an effect on cell membrane modulating cytoskeletal structures [17]. This effect can be mimicked by thiol group alkylation with N-ethylmaleimide (NEM) which alkylates a number of proteins including several within the cytoskeleton [18,19], which is itself a part of a structural and functional unit with the cell membrane.…”

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confidence: 99%

Abnormal regulation of cell membrane fluidity in diabetic nephropathy

1998

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Diabetic nephropathy is a condition that appears to arise from an interaction between poor glycaemic control [1] and inherited factors [2]. Insulin-dependent diabetic (IDDM) patients with nephropathy are characteristically hypertensive, have diabetic retinopathy, are relatively insulin resistant and have raised levels of serum triglycerides [3±6]. In addition, rates of activity of cell membrane cation transporters, such as the sodium-hydrogen exchanger [7,8] and the sodium-lithium countertransporter (Na-Li CT) [9±11] are increased in patients with diabetic kidney disease. The very close association of these abnormalities suggests a common aetiology. Na-Li CT has a large inherited component [12] and, although it appears to have no pathophysiological role, may be an inherited marker for an abnormality Diabetologia (1998) Summary An abnormality of the physical properties of the cell membrane may underlie the defect that unites the clinical and biochemical abnormalities found in subjects with diabetic nephropathy. The cell membrane is linked both structurally and functionally with the cytoskeleton. The fluorescence anisotropy, a measure of membrane fluidity, was studied at baseline and after modulation of cytoskeletal proteins by thiol group alkylation with N-ethylmaleimide (NEM). 1,6-diphenyl-1,3,5-hexatriene (DPH) was used to assess anisotropy in the deep hydrophobic regions of the lipid bilayer and trimethylammoniumdiphenylhexatriene (TMA-DPH) was used to assess the superficial, relatively hydrophilic regions. We compared 17 subjects with insulin-dependent diabetes mellitus (IDDM) and nephropathy with 17 control subjects with IDDM and 24 non-diabetic control subjects. Median TMA-DPH anisotropy (0.271 (0.239±0.332) vs 0.269 (0.258±0.281) vs 0.275 (0.246± 0.287)) and DPH anisotropy (0.221 (0.193±0.261) vs 0.227 (0.197±0.253) vs 0.226 (0.193±0.245)) were similar in erythrocytes from the three groups. However after alkylation of protein thiol groups with NEM clear differences emerged. In the control subjects with and without IDDM there was a significant fall in TMA-DPH anisotropy compared to the subjects with diabetic nephropathy in whom the addition of NEM had no effect (DTMA-DPH anisotropy ±0.005 (±0.020± + 0.006) vs ±0.005 (±0.011± + 0.016) vs + 0.002 (±0.010 ± + 0.008) p < 0.001). This finding was confirmed when the deep regions of the lipid bilayer were assessed using DPH (DDPH anisotropy ±0.017 (±0.029 ± ± 0.007.) vs ±0.015 (±0.029 ± + 0.001) vs + 0.003 (±0.021 ± + 0.018) p < 0.001). We conclude that cytoskeletal modulation of the physical properties of the cell membrane lipids by proteins is abnormal in subjects with diabetic nephropathy. Such an abnormality could explain some of the clinical and metabolic abnormalities found in this condition. [Diabetologia (1998) 41: 337±342]

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“…The red cells were washed twice with 150 mmol/L NaCl, lysed hypotonically in 5 mmol/L phosphate buffer, pH 8, and centrifuged at 20 000 g for 20 min at 4°C. The resultant membranes were washed with phosphate buffers of decreasing molarity to remove the hemoglobin, according to Burton (14).…”

Section: Methodsmentioning

confidence: 99%