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Summary. Filtrability of erythrocytes obtained from uncontrolled Type I (insulin-dependent) diabetic patients is abnormal, but is corrected by insulin added in vivo or in vitro. As erythrocyte filtrability depends on several determinants, we chose to study a membrane property of erythrocytes from diabetic subjects. Membrane fluidity was studied by fluorescence polarization using a lipophilic probe, the diphenyl-hexatriene and the Coulter Epics V together with a laser Spectra-physics 2000. Fluorescence polarization values obtained for 31 normal subjects (0.253 +0.043 SD) and 31 uncontrolled Type 1 diabetic patients (0.231 + 0.043 SD) were significantly different (p < 0.01). Insulin (2.5.10 -9 mol/1) added in vitro increased Given a relationship between the lipid bilayer and membrane cytoskeleton proteins, this insulin-correctable abnormality of erythrocyte membrane fluidity may be an important determinant of the rheological behaviour of erythrocytes from diabetic patients.Keywords: Membrane, fluorescence polarization, erythrocytes, diabetes, insulin.The erythrocytes &uncontrolled Type 1 (insulin-dependent) diabetic patients have abnormal rheological properties [1][2][3][4]. Modifications in the erythrocyte membrane could be the cause of these theological abnormalities. Biochemical abnormalities have been described [5][6][7] in the membrane, and change in its viscosity have been demonstrated by the fluorescence polarization technique [7][8][9] or electron spin resonance [10]. However, these results have been challenged [11].We have previously observed that the poor filtrability of erythrocytes from uncontrolled Type 1 diabetic patients was rapidly corrected by insulin added in vivo or in vitro [3,4].The aim of this study was therefore to verify whether insulin directly modified the membrane fluidity assessed by fluorescence polarization if such an abnormality was found in cells from diabetic patients. For this purpose, ghosts prepared from erythrocytes originating from uncontrolled Type 1 diabetic patients and matched controls were incubated with and without insulin. Fluorescence polarization was studied with a lipophilic probe, the 1,6 diphenyl-l,3,5 hexatriene (DPH). Subjects and methodsThe subjects were 31 Type I (insulin-dependent) diabetic patients, 20 males and 11 females, aged 26 to 64 years (mean + SD = 44 _+ 16), uncontrolled at the time of the study. None of the patients were smokers, and women did not use oral contraceptive agents. Diabetes duration ranged from 1 to 26 years (mean + SD = 9.6 + 7 years). Two patients had macroproteinuria (i.e. > 500 mg/day) but serum creatinine did not exceed 100 btmol/l in any of the patients. Nine had background retinopathy at fundus examination after papillary dilatation. Patients with proliferative retinopathy or symptoms of cardiovascular disease were excluded from the study. Treatment consisted of two or three insulin injections per day except for two cases treated with one daily insulin injection. Glycosylated haemoglobin values, assessed by microchromatography at...

We had shown in non diabetic healthy subjects with Body Mass Index (BMI) varying largely, a significant correlation (r) between PAI activity levels and BMI : (r=0.66) and insulinemia (r=0.52).PAI levels were then studied in non diabetic Obese women (0)(n=50) and in age matched healthy women with normal BMI (N) (m ± SEM) = 0 versus N : BMI : 33.4± 0.8/ 20.2± 0.8 ; plasma insulin (Ins -uu/ml) : 22.7±1.5/12±1; Triglyceride(TG-mmol/1):1.240.09/0.8±0.1.The low value of euglobulin fibrinolytic activity (EFA) in Obese was due to high levels of PAI 1 : 0 versus N : EFA (mm) : 5.2 ±0.3/ 9 ±0.3 ; PAI activity (PAIact.- Verheijen's method-u/ml) :14 ± 2.1/5.04 ±0.6 -(p 0.01). In 10 0 and 10 N PAIact and PAI 1 antigen (PAI 1 Ag- Kruithof's method-ng/ml) were determined in parallel : 0 versus N : PAIact.: 29.4±3.8/ 5.8±0.9 ; PAI 1 Ag : 100±14.2/19.7 ±1.7, (p0.01). In Obesegroup correlations between, PAIact. and BMI (r=0.51), and insulin (r=0.69) and Triglyceride (r=0.48) were significant (p 0.01).When in Obese subjects, insulinemia was decreased by 24 hours Fast (n=10) or by 15 days Metformin treatment (1.7g/day) (n=9), PAI activity (measured on fibrin plates)decreased significantly in a parallel way : compared to initial values -after 24 hours Fast =Ins : 75 %, PAIact. 73% -after Metformin treatment=Ins :75%, PAIact. :57%, TG :73%.From these results, a direct action of insulin on the synthesis cells of PAI 1 could be evoked. An effect of Triglyceride levels cannot be excluded, the variation of Triglyceride, insulin, PAI levels being parallel.As hyperinsulinemia, hypertriglyceridemia are risk factors for atherothrombosis, as there is a link between insulin, triglyceride, PA Inhibitor 1 levels, the pathogenic role of hyperinsulinemia and hypertriglyceridemia in the development of atherothrombosis could be in part mediated by plasma hypofibrinolysis due to high level of PAI 1.

Erythrocytes from diabetic patients show abnormal rheology. Pentoxifylline, a methylxanthine, improves the abnormal deformability of diabetic erythrocytes, but its mechanism of action remains unclear. We have studied the effect of pentoxifylline on the lipid order of erythrocyte membranes from controls and patients with Type I diabetes. We studied the structural organization of membrane lipids in individual erythrocyte ghosts by fluorescence polarization using a cell sorter. Fluorescence polarization values (P) for 17 controls (P = 0.244) and 20 diabetic patients (P = 0.215) were significantly different. Pentoxifylline added in vitro had no effect on normal membranes, but significantly increased at 10(-5) mol X l-1 (P = 0.233), and normalized at 10(-4) mol X l-1 (P = 0.243), the P value of membrane ghosts from diabetics.