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Introduction: Atopic dermatitis (AD) is a chronic, inflammatory skin disorder with eczematous and pruritic lesions. Topical moisturisers and either topical corticosteroids or calcineurin inhibitors are usually recommended. Restoring the skin barrier function alleviates AD symptoms. Objective: To evaluate the efficacy of a new moisturiser compared to commercially available products in an AD murine model. Methods: Experimental AD was induced with topical applications of 2,4-DiNitroChloroBenzene (DNCB) on the shaved back skin of BALB/c mice from Day 1 to Day 38. Mice were randomized to either Vehicle/-, DNCB/-, or DNCB/Eczekalm (test product), DNCB/Atopiclair®, or DNCB/Lipikar (reference products) groups. Once daily application of either Eczekalm or Atopiclair® or Lipikar on the AD lesion was performed from Day 32 to Day 38. The AD severity index (ADSI) and animal behaviour were monitored throughout the study. The trans-epidermal water loss (TEWL) was measured on the sacrifice day (Day 39). Results: At Day39, ADSI in the DNCB/Eczekalm, DNCB/Lipikar, and DNCB/Atopiclair® groups were significantly lower by -70%, -68%, and -57%, respectively, as compared to DNCB/- (p Conclusion: Eczekalm treatment significantly reduced the inflammatory effects due to AD and itching episodes and restored the skin barrier function.

Resume Cet essai clinique randomise, croise, a demontre la securite et l’efficacite d’un dispositif medical de neurostimulation electrique transcutanee rechargeable (TENS) chez des sujets souffrant de douleurs articulaires et musculosquelettiques chroniques. Cette etude montre une diminution de la consommation des antalgiques non morphiniques, des anti-inflammatoires et des antalgiques morphiniques, lorsque l’on compare, sur deux periodes de 28 jours, la prise medicamenteuse a visee antalgique chez les patients lorsqu’ils utilisent le TENS et lorsqu’ils ne prennent que leur traitement antalgique habituel. Le soulagement des douleurs chroniques chez les patients lorsqu’ils utilisent le TENS a egalement ete evalue. Outre la rapidite d’action du TENS au cours de l’application, la remanence de l’effet antalgique semble perdurer plusieurs heures apres l’application, ce qui a pu contribuer a l’epargne therapeutique et a l’attenuation de la gene fonctionnelle occasionnee par les douleurs chroniques au quotidien. Son efficacite, statistiquement et cliniquement significative, rapide et durable, sur le soulagement de la douleur, permettant de diminuer la prise d’antalgiques, son caractere non invasif et sa tolerance, ainsi que sa simplicite d’utilisation, font du dispositif d’electrotherapie rechargeable TENS, teste dans cette etude, une solution antalgique non pharmacologique susceptible d’etre associee ou de remplacer les traitements pharmacologiques dans la prise en charge des douleurs articulaires et musculosquelettiques chroniques.

SummaryAims Guidelines propose additional therapy to statin to treat elevated triglycerides (TG) and low high-density lipoprotein cholesterol (HDLC) in dyslipidemic patients. We evaluated the effects of new fixed-dose combinations (FDC) of fenofibrate/simvastatin on plasma lipids versus simvastatin or fenofibrate monotherapies. Methods Subjects with mixed dyslipidemia at high or very high cardiovascular risk on stable statin therapy for at least 3 months were included in a randomized, double-blind, active-control, parallel-group study. Patients were treated with FDC fenofibrate/simvastatin 145/20 mg or 145/40 mg, simvastatin 20 mg or 40 mg, or fenofibrate 145 mg for 12 weeks. Plasma lipids, C-reactive protein, and cystatin C were measured before and after treatments. Differences in % changes were compared between FDC fenofibrate/simvastatin and monotherapies. Results Significant differences between FDC fenofibrate/simvastatin and simvastatin monotherapies were observed for the % change of TG (LS mean difference [two-sided 95% CI]: −32.2% [−38.6%, −25.8%], P

Gout is a painful disorder and is common in type 2 diabetes. Fenofibrate lowers uric acid and reduces gout attacks in small, short-term studies. Whether fenofibrate produces sustained reductions in uric acid and gout attacks is unknown.In the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) trial, participants aged 50-75 years with type 2 diabetes were randomly assigned to receive either co-micronised fenofibrate 200 mg once per day or matching placebo for a median of 5 years follow-up. We did a post-hoc analysis of recorded on-study gout attacks and plasma uric acid concentrations according to treatment allocation. The outcomes of this analysis were change in uric acid concentrations and risk of on-study gout attacks. The FIELD study is registered with ISRCTN, number ISRCTN64783481.Between Feb 23, 1998, and Nov 3, 2000, 9795 patients were randomly assigned to fenofibrate (n=4895) or placebo (n=4900) in the FIELD study. Uric acid concentrations fell by 20·2% (95% CI 19·9-20·5) during the 6-week active fenofibrate run-in period immediately pre-randomisation (a reduction of 0·06 mmol/L or 1 mg/dL) and remained -20·1% (18·5-21·7, p0·0001) lower in patients taking fenofibrate than in those on placebo in a random subset re-measured at 1 year. With placebo allocation, there were 151 (3%) first gout events over 5 years, compared with 81 (2%) among those allocated fenofibrate (HR with treatment 0·54, 95% CI 0·41-0·70; p0·0001). In the placebo group, the cumulative proportion of patients with first gout events was 7·7% in patients with baseline uric acid concentration higher than 0·36 mmol/L and 13·9% in those with baseline uric acid concentration higher than 0·42 mmol/L, compared with 3·4% and 5·7%, respectively, in the fenofibrate group. Risk reductions were similar among men and women and those with dyslipidaemia, on diuretics, and with elevated uric acid concentrations. For participants with elevated baseline uric acid concentrations despite taking allopurinol at study entry, there was no heterogeneity of the treatment effect of fenofibrate on gout risk. Taking account of all gout events, fenofibrate treatment halved the risk (HR 0·48, 95% CI 0·37-0·60; p0·0001) compared with placebo.Fenofibrate lowered uric acid concentrations by 20%, and almost halved first on-study gout events over 5 years of treatment. Fenofibrate could be a useful adjunct for preventing gout in diabetes.None.

Diabetic retinopathy (DR) is one of the leading risk factors and causes of blindness worldwide. Tight glucose and blood pressure control has been shown to significantly decrease the risk of development as well as the progression of retinopathy and represents the cornerstone of medical management of DR. The two most threatening complications of DR are diabetic macular edema (DME) and proliferative diabetic retinopathy (PDR). Photocoagulation is standard treatment for both DME and PDR. However, some patients suffer permanent visual loss despite therapy. Treatment with fibrates first showed reduction in hard exudates, an effect subsequently shown with statins in short term studies, in particular two randomized studies in patients with macular edema. In the FIELD study which pre-specified microvascular outcomes, fenofibrate reduced laser treatment for DME or PDR by 31%: 164 (3.4%) patients on fenofibrate vs. 238 (4.9%) on placebo (p < 0.001). In the ophthalmology sub-study of FIELD, the composite exploratory endpoint of 2-step progression of ETDRS retinopathy grade, macular edema or laser treatment was significantly reduced by 34%: 53 (11.1%) patients on fenofibrate vs. 75 (16.1%) on placebo (p=0.022). Conversely, there was no reduction in laser treatment or reduced progression of retinopathy in two large scale studies of statins where cardiovascular events were significantly reduced. Neither class of lipid-lowering drugs consistently improved visual acuity. In the ACCORD-EYE study, the combination of fenofibrate and simvastatin reduced by 40% the rate of progression of diabetic retinopathy compared with simvastatin alone. Other studies are needed to establish the place of lipid lowering drugs in the treatment of macular edema and the prevention of vision loss.

Purpose: Urinary peptidome changes and discrimination for potential renal glomerular and tubular damage after 6 wk of fenofibrate treatment were evaluated in 26 healthy subjects. Experimental design: Peptide profiling was performed in urine samples before and after treatment using high-resolution capillary electrophoresis coupled with electrospray ionization mass spectrometry. Results: A panel of 88 fenofibrate-sensitive peptides was detected with a frequency of ≥50% before and after treatment. This was reduced to 36 peptides by repeating the comparison ten times by randomly excluding samples at each time-point. Nineteen peptides were consistent and reliable biomarkers after an additional comparison with an age and sex-matched subject control group. Levels of peptides identified as fragments of Collagen α-1 (I), Collagen α-1 (XVII), Collagen α-2 (VIII) or sodium/potassium-transporting ATPase subunit gamma were reduced after fenofibrate treatment. Classification scores for renal tubular and glomerular damages determined by support vector machine based biomarker models increased after treatment but remained below pathological score cutoff values. Conclusions and clinical relevance: Fenofibrate treatment led to minor modifications of the urinary proteomic profile in a way that does not create safety issues affecting glomerular and tubular functions. Urinary peptide profiling proved to be appropriate to monitor drug pharmacological effects in a clinical setting.

Objective The association between polymorphisms in candidate genes related to lipoprotein metabolism and the reduction in plasma triglyceride (TG) in response to fenofibrate treatment was evaluated in subjects with type 2 diabetes treated with micronized fenofibrate (200 mg/day) for at least 3 years in the Diabetes Atherosclerosis Intervention Study. Methods The cholesteryl ester transfer protein Taq1B, LPL S447X, hepatic lipase -514 C-->T, peroxisome-proliferator-activated receptors alpha (PPARA) L162V and G/C intron 7 polymorphisms and the apolipoprotein E2/E3/E4 alleles were genotyped using PCR and restriction enzyme digestion. Subjects were divided into high TG-responders (with >30% TG relative reduction after treatment) and low TG-responders. Results The frequency of the PPARA intron 7 G/G genotype was higher in high TG-responders than in low TG-responders (85% vs. 69%, P 30% after fenofibrate treatment in patients with type 2 diabetes. (C) 2004 Lippincott Williams Wilkins

Background— The Diabetes Atherosclerosis Intervention Study showed that treatment with fenofibrate decreases progression of coronary atherosclerosis in subjects with type 2 diabetes. We determined whether on-treatment plasma lipid concentrations and LDL particle size contribute to the favorable effect of fenofibrate on the progression of coronary artery disease (CAD). Methods and Results— A total of 418 subjects with type 2 diabetes were randomly assigned to 200 mg micronized fenofibrate daily or placebo. The mean follow-up time was 39.6 months. LDL peak particle diameter (LDL size) was determined by polyacrylamide gradient gel electrophoresis from 405 subjects at baseline and at the end of the study. Progression of CAD was measured with quantitative coronary angiography. LDL size increased significantly more in the fenofibrate group than in the placebo group (0.98±1.04 versus 0.32±0.92 nm, P r =−0.16, P =0.002) and decreases in minimum ( r =−0.11, P =0.030) and mean ( r =−0.10, P =0.045) lumen diameter. High on-treatment LDL cholesterol, apolipoprotein B, and triglyceride concentrations were also associated with the progression of CAD. In regression analyses, small LDL size added to the effect of LDL cholesterol and apolipoprotein B on the progression of CAD. Similar associations were observed in the fenofibrate group, whereas in the placebo group, lipoprotein variables were not significantly correlated with the progression of CAD. Conclusions— Changes in LDL size and plasma lipid levels account for part of the antiatherogenic effect of fenofibrate in type 2 diabetes.

This study evaluated the postprandial (PP) response to an oral fat load in 28 male patients with type 2 diabetes (mean HbA1c of 5.1%), all receiving metformin and performing physical exercise, compared with healthy subjects. The effects of micronized fenofibrate (200 mg once daily) on triglycerides (TG) and retinyl palmitate (RP) responses, lipoprotein mass concentrations, post-heparin lipase activities and coagulation factors were investigated after a 16-week double-blind, placebo-controlled period. Higher and delayed TG response after the oral fat load (P0.001) corresponding to increases in both intestinally and endogenous TG-rich lipoproteins and lower lipoprotein lipase (LPL) activity 30 and 60 min post-heparin injection (P0.05) were observed in the patients as compared with controls. Fasting PAI-1 activity, 6 h PP Factor VII and PAI-1 activities were higher in patients (P=0.036, P=0.032 and P=0.017, respectively). After fenofibrate treatment, TG and RP responses and peak LPL activity were no more significantly different from controls at baseline. Compared with placebo, fasting TG-rich lipoproteins and HDL(3) mass concentrations were significantly lower and higher, respectively; PP chylomicrons and very low density lipoprotein (VLDL) mass concentrations were lower; fasting and PP fibrinogen levels were significantly reduced after fenofibrate treatment. Diabetes control was unchanged throughout the study. Fenofibrate normalized the abnormal PP response and improved the fasting lipoprotein abnormalities in patients with type 2 diabetes and optimal glucose control.

Cross-sectional data suggest that bezafibrate increases betaine excretion in dyslipidemic patients.We aimed to demonstrate that fenofibrate induces increased betaine excretion in normal subjects and explore whether other 1-carbon metabolites and osmolytes are similarly affected.Urine was collected from 26 healthy adults before and after treatment with fenofibrate (145 mg/day for 6 weeks). Excretions of betaine, N,N-dimethylglycine, free choline, myo-inositol, taurine, trimethylamine-N-oxide, carnitine, and acetylcarnitine were measured by liquid chromatography with mass spectrometric detection.Fenofibrate increased the median betaine excretion from 7.5 to 25.8 mmol/mole creatinine (median increase 3-fold), P.001. The median increase in N,N-dimethylglycine excretion was 2-fold (P.001). Median choline excretion increased 12% (significant, P = .029). Participants with higher initial excretions tended to have larger increases (P.001 in all 3 cases). Fenofibrate did not significantly change the median excretions of myo-inositol, taurine, trimethylamine-N-oxide, and carnitine. The excretion of acetylcarnitine decreased 4-fold on treatment, with no correlation between the baseline and after-treatment excretions. Changes in all urine components tested, except trimethylamine-N-oxide, positively correlated with changes in betaine excretion even when the median excretions before and after were not significantly different.Fibrates increase betaine, and to a lesser extent N,N-dimethylglycine and choline, excretion. Other osmolytes are not elevated. Because the increase in betaine excretion depends on the baseline excretion, large increases in excretion in the metabolic syndrome and diabetes (where baseline excretions are high) could be expected. Replacement with betaine supplements may be considered.

Peroxisome proliferator-activated receptors (PPARs), with three existing isoforms (PPAR α, PPAR β/δ, and PPAR γ), belong to the nuclear receptors subfamily. The PPAR machinery involves the binding of natural (fatty acids and prostaglandins), synthetic (mainly fibrates for PPAR α and thiazolidinediones for PPAR γ and new dual and pan-PPAR agonists), and selective PPAR modulators, coactivators, and corepressors with enzymatic activities and various metabolic transformations turning PPARs toward activation or to degradation. Among PPAR activators in clinical development for type 1 or type 2 diabetes and dyslipidemia, some have been discontinued for safety reasons or for no additional benefit over existing drugs. Knowing the pleiotropic effects of PPAR agonists, search for new natural PPAR ligands and clinical development of new target indications represent the main future of this class of drugs.

The aim of the present study was to investigate the effect of saturated, monounsaturated and polyun-saturated non-esterified fatty acids (NEFA) on lipoprotein fluidity by using the electron spin resonance (ESR) method. The fluidity of the lipid phase of lipoproteins was evaluated by calculating from ESR spectra the S parameter of three different positional isomers of spin-labeled stearic acid incorporated into the lipoprotein. In non-enriched lipoproteins, S values were higher in high-density lipoprotein 3 (HDL3) than in low-density lipoprotein (LDL) indicating that the surface of HDL, was more ordered. Prior incubation of lipoprotein particles with NEFA significantly reduced S values, indicating an increased lipoprotein fluidity as compared with non-supplemented homologous samples. In NEFA-enriched lipoproteins, the modifications in fluidity were shown to be dependent on the structure of the NEFA acyl carbon chains. Medium-chain fatty acids [lauric (12:0) and myristic (14:0) acids] appeared to be better fluidizing molecules as compared with both. shorter [octanoic (8:O) and decanoic (10:0) acids] and longer [palmitic (16:0) and stearic (18:0)acids] homologues. In addition, introducing at least one double bond in the acyl carbon chain significantly increased the ability of NEFA to reduce S as compared with saturated homologues. In both LDL and HDL3, the extent of the modifications of the molecular mobility at the lipoprotein surface was dependent on the final NEFA/lipoprotein ratio. In conclusion, these results suggest that the ability of NEFA to modulate the activity of the cholesteryl ester transfer protein might relate in part to alterations in fluidity at the lipoprotein surface.

Fibrates or PPAR alpha agonists, in particular fenofibrate, are known to increase homocysteine levels (Hcy). A 3 to 5 micromol/L increase in Hcy is commonly observed within the first few weeks of fenofibrate treatment; it then persists in plateau when treatment is continued and is reversible upon its cessation. Since its description in 1999, this pharmacological effect attracted a great deal of attention as epidemiological studies in most populations have shown that elevated Hcy levels i.e.Hcy> or =15 micromol/L are associated with an increased risk of cardiovascular events (CVD), venous thromboembolic events (VTE) and possibly cognitive disorders and bone fractures. Chronic kidney disease is also associated with elevated Hcy levels and since fenofibrate increases creatinine levels by about 10-12 micromol/L, a relationship between Hcy and creatinine was postulated. Animal studies have shown that the Hcy increase is PPARalpha dependent but to date animal or human studies have not provided a clear mechanism. In particular, fenofibrate treatment does not change vitamin B levels; however, vitamin B supplements reduce fenofibrate-induced Hcy elevation but not the concomitant cysteine elevation. Similarly, the increase in creatinine with fenofibrate only partially accounted for by a reduction in glomerular filtration rate (GFR) since creatinine production is also increased by 5-10%. In the FIELD study, a placebo-controlled study in 9795 patients with type 2 diabetes, fenofibrate over 5 years reduced non-fatal cardiovascular events and microvascular events such as albuminuria, the need for laser treatment for proliferative retinopathy or maculopathy and amputations but did not reduce fatal events. The increase in Hcy was indeed much larger that what would be explained by creatinine elevation and independent from baseline kidney function. Although baseline Hcy and creatinine levels were associated with subsequent risk of CVD, as suggested by epidemiology, their respective elevation was not. Of interest, after withdrawal of fenofibrate, a potential renoprotective effect was unmasked, as estimated GFR was 5 ml/min/1.73 m2 higher in previous fenofibrate-allocated patients than in previous placebo-allocated patients. There was no suggestion that Hcy elevation was associated with VTE (which were increased by an unknown mechanism) or bone disorders. In conclusion, the discrepancy between the role of baseline Hcy levels in epidemiology and the absence of effect when altering its levels by either decreasing them with vitamin B supplements or increasing them with fenofibrate, suggests that the risk factor(s) behind homocysteine should be found. Nevertheless, other studies are also needed to understand the mechanism and the implications of the moderate homocysteine and creatinine elevations with fenofibrate and other PPARalpha agonists.

Fibrates are widely prescribed lipid-lowering drug in the treatment of dyslipidemia. Their main clinical effects, mediated by peroxisome proliferative activated receptor (PPAR) alpha activation, are a moderate reduction in total cholesterol and low-density lipoprotein cholesterol (LDL-C) levels, a marked reduction in triglycerides (TG) and an increase in high-density lipoprotein cholesterol (HDL-C), usually dependent of their baseline levels and dyslipidemia type. A beneficial effect on cardiovascular outcomes but also on inflammatory and thrombogenesis pathways as well as antioxidant properties have been evidenced conferring other pleiotropic effects to fibrates. Diabetic retinopathy, nephropathy and neuropathy are the major microvascular complications of Type 2 diabetes mellitus (T2DM) and their presence can accentuate the risk of cardiovascular disease. Hyperglycemia, hypertension, genetic susceptibility among other risk factors play a significant role in the development and progression of these complications. Plasma lipid abnormalities are also involved in the pathogenesis of microvascular diseases suggesting a potential benefit of lipid lowering drugs in their prevention. Clofibrate was the first fibrate in the 60's to show an improvement in the retinal hard exudation in subjects with diabetic retinopathy. Recently, in the Fenofibrate Intervention in Event Lowering in Diabetes (FIELD) study fenofibrate treatment demonstrated a significant 30% reduction in the need for laser therapy in patients with and without known diabetic retinopathy, and more particularly in the first course of laser treatment for both macular edema and proliferative retinopathy. In addition, fenofibrate treatment was associated with less albuminuria progression and reduced risk of non traumatic distal amputations. These results, along with previous evidence of positive effects on microvascular complications, suggest that fibrates, and particularly fenofibrate, offer good opportunity to prevent the most serious complications of diabetes.

Fenofibrate was associated with increases in serum creatinine concentrations. The effect of short-term fenofibrate treatment on kidney function was investigated in subjects with normal kidney function.Double-blind, crossover, placebo-controlled.24 middle-aged subjects with normal kidney function (estimated creatinine clearanceor = 80 mL/min).Subjects were treated with fenofibrate (160-mg/d tablet) and placebo in two 6-week periods separated by a washout.The primary outcome measure was glomerular filtration rate measured by means of inulin clearance, with a test of noninferiority to rule out a change in the 95% confidence interval (CI) greater than 20%. Secondary outcomes included effective renal plasma flow measured by means of para-aminohippurate (PAH) clearance, creatinine clearance, creatinine secretion (ratio of creatinine to inulin clearance), serum cystatin C and uric acid, and urinary excretion of creatinine. Glomerular and tubular damage was evaluated by using albumin and retinol-binding protein levels and N-acetyl-beta-d-glucosaminidase activity.Inulin clearance was unchanged after fenofibrate (change [Delta] between treatments on 6-week values, 0.8 mL/min; 95% CI, -10.5 to 12.2; P = 0.9), but PAH clearance decreased (Delta, -33; 95% CI, -66 to -1; P = 0.05). Changes in inulin and PAH clearances were not greater than 20%. Plasma creatinine level increased (Delta, 0.11 mg/dL; 95% CI, 0.05 to 0.18; P0.05), and creatinine clearance decreased (Delta, -9.5 mL/min; 95% CI, -14.4 to -4.7; P0.001). Creatinine secretion and urinary creatinine excretion were unchanged (Delta, -0.05; 95% CI, -0.11 to 0.02; P = 0.2; Delta, 0.37 g/24 h; 95% CI, -0.13 to 0.88; P = 0.1, respectively). Plasma cystatin C level increased (Delta, 0.18 mg/L; 95% CI, 0.03 to 0.34; P = 0.02) and serum uric acid level decreased (Delta, -0.7 mg/dL; 95% CI, -1.2 to -0.3; P = 0.1). Urinary albumin and retinol-binding protein levels were unchanged, but urinary N-acetyl-beta-d-glucosaminidase activity increased (Delta, 20.0 mumol/h/mmol creatinine; 95% CI, 9.3 to 30.7; P = 0.001).Short treatment duration and inclusion of healthy subjects precludes conclusions about effects of longer term use in patients with kidney disease. Small changes in glomerular filtration rate may be difficult to detect by using clearance methods. Interference with the creatinine assay cannot be excluded.Short-term fenofibrate treatment did not alter glomerular filtration rate by more than 20% in subjects with normal kidney function, but a smaller decrease cannot be ruled out. Increased serum creatinine levels may be caused by decreased creatinine clearance. The explanation for decreased creatinine clearance and increased serum creatinine levels in this study is not clear.

Microalbuminuria is an early marker of diabetic nephropathy and an independent risk factor for cardiovascular disease. In the Diabetes Atherosclerosis Intervention Study (DAIS), treatment of people with type 2 diabetes with micronized fenofibrate for an average of 38 months reduced the progression of angiographically evaluated coronary artery disease and improved lipoprotein level abnormalities compared with placebo. The aim of this analysis is to study the influence of the treatment on changes in urinary albumin excretion.Microalbuminuria was measured on 2 to 3 occasions by using timed overnight samples at baseline and yearly thereafter in 314 DAIS participants (77 women, 237 men; average age, 56 years); all except 3 participants had either a normal albumin excretion rate (20 microg/min; n = 214) or microalbuminuria (albumin, 20 to 200 microg/min; n = 97) before randomization. Tabulated shifts (between normal, microalbuminuria, and macroalbuminuria) from baseline to last observed values were compared between treatment groups by means of chi-square or Fisher's exact test.Fenofibrate significantly reduced the worsening of albumin excretion (fenofibrate, 8% versus placebo, 18%; P0.05). This effect was caused mostly by reduced progression from normal albumin excretion to microalbuminuria: 3 of 101 participants in the fenofibrate group versus 20 of 113 participants in the placebo group (P0.001). Overall, changes in albumin excretion were independent of age or changes in lipid or creatinine levels, weight, or blood pressure.Improvement in lipid profiles with fenofibrate in patients with type 2 diabetes was associated with reduced progression from normal albumin excretion to microalbuminuria.

OBJECTIVE The purpose of the present study was to investigate liver microsomal membrane fluidity simultaneously with membrane fatty acid composition and desaturase activities in spontaneously hypertensive rats (SHR). DESIGN AND METHODS The membrane fluidity was determined, after electron spin resonance (ESR) measurement, in SHR compared with normotensive Wistar-Kyoto (WKY) rats, by calculating the order parameter S from ESR spectra of 5-nitroxide stearate and 10-nitroxide stearate, used as spin-labelled fatty acids. Desaturase activities were measured by incubating SHR and WKY rat liver microsomes with [14C]-radiolabeled fatty acids as substrates for desaturation reactions. The fatty acid composition of liver microsomal membranes was determined by gas-liquid chromatography. RESULTS Whereas no significant difference between S of 5-nitroxide stearate was observed for SHR and WKY rats, S of 10-nitroxide stearate was significantly lower in SHR than it was in WKY rat microsomal membrane, indicating that the core microsomal membrane fluidity was higher in SHR. Significant differences between fatty acid compositions were observed for SHR and WKY rat microsomal membranes. Delta9 and n-6 delta6 microsomal desaturase activities were significantly lower in SHR. CONCLUSION These results suggest that the higher liver core microsomal membrane fluidity observed in SHR might be dependent on the increased proportion of mono-unsaturated fatty acids. Such observed modifications and the alterations in delta9 and n-6 delta6 desaturase activities suggest that an impaired polyunsaturated fatty acid biosynthesis is related to changes in microsomal membrane fluidity in hypertension.