Circulating oxidized low-density lipoprotein and common carotid artery intima-media thickness in a random sample of middle-aged men

Circulating oxidized low-density lipoprotein (oxLDL) has been suggested to play an important role in atherosclerosis development. According to previous observations, oxLDL correlates with clinically manifest coronary and carotid artery disease. We investigated the association between the oxLDL concentration measured directly in plasma and common carotid artery intima-media thickness (IMT) in a population-based, case-control study in middle-aged men from Southern Finland. oxLDL was determined in 214 men by a commercially available sandwich ELISA test (Mercodia). Carotid artery IMT was measured at 12 standardized segments by B-mode ultrasonography (at the near and far wall of the left and right common carotid arteries, bifurcations and internal carotid arteries), and the overall mean maximum IMT (MMaxIMT) was calculated. The MMaxIMT of the carotid arteries was significantly associated with circulating oxLDL (r_s=0.16, p=0.018). In a stepwise multiple regression model with MMaxIMT as dependent variable and systolic blood pressure, smoking, oxLDL, HDL cholesterol and apolipoprotein B as covariates, systolic blood pressure (=0.22, p<0.001), oxLDL (=0.15, p=0.022) and smoking (=0.17, p=0.014) showed an independent association with IMT (R²=0.10, p<0.001). Our results show that oxLDL measured directly from plasma is independently associated with subclinical carotid artery atherosclerosis in middle-aged men.     

Lower wall shear rate of the common carotid artery in treated type 2 diabetes mellitus with metabolic syndrome

Arterial sites with low wall shear stress (WSS) are more prone to the development of atherosclerotic plaques, as was observed in carotid arteries in subjects with atherosclerosis risk factors. Type 2 diabetes mellitus (DM), hypertension, hyperlipidemia and other components of the metabolic syndrome, are associated with high risk for symptomatic cerebrovascular disease. It was shown by others that untreated type 2 DM is associated with lower WSS in common carotid arteries. However, the cardiovascular risk of type 2 DM could be modified by therapy. The aim of our study was to test the hypothesis that treated type 2 DM subjects with metabolic syndrome still have lower WSS in common carotid arteries than healthy controls. We enrolled 26 compensated DM subjects with metabolic syndrome, treated by metformin, statins and ACEI for more than 6 months, and 22 aged-comparable healthy controls. Wall shear rate (WSR) was used as a measure of WSS. A linear 3-11 MHz probe was used to measure blood velocity and internal diameter in the common carotid arteries. We compared observed values of WSR adjusted for age by ANCOVA. Wall shear rate was significantly lower in DM group than in control subjects: peak (systolic) values of wall shear rate were 410+/-130 s(-1) vs. 487+/-111 s(-1) (p<0.005). DM subjects had significantly lower WSR, because of both thinner lumen and slower blood flow velocities. Lower WSR was accompanied by higher IMT (0.73+/-0.12 mm vs. 0.64+/-0.11 mm, p<0.001). Treated subjects with compensated type 2 DM with metabolic syndrome still have atherogenic hemodynamic profile. These findings might help to understand faster progression of atherosclerosis in diabetic subjects with metabolic syndrome despite up-to-date medication.     

Increased carotid thickness in subjects with recently-diagnosed diabetes from rural cameroon

Background

We have recently shown a high prevalence of diabetes and obesity in rural Cameroon, despite an improved lifestyle. Diabetes in rural Africa remains underdiagnosed and its role in increasing risk of atherosclerosis in these populations is unknown. We investigated the prevalence of carotid atherosclerosis and cardiovascular risk factors in a population of subjects with recently-diagnosed diabetes from rural Cameroon.

Methodology/Principal Findings

In a case-control study, carotid intima-media thickness (IMT) was measured in 74 subjects with diabetes (diagnosed <2 years), aged 47–85 and 109 controls comparable for age and sex. Subjects were recruited during a health campaign conducted in April 2009. Blood glucose control (HbA1c, fasting blood glucose) and major cardiovascular risk factors (complete lipid panel, blood pressure) were also measured. Mean carotid IMT was higher in subjects with diabetes than healthy controls at each scanned segment (common, internal carotid and bulb) (P<0.05), except the near wall of the left bulb. Vascular stiffness tended to be higher and pressure-strain elastic modulus of the left carotid was increased in subjects with diabetes than controls (P<0.05), but distensibility was similar between the two groups. At least one plaque >0.9 mm was found in 4%, 45.9% and 20% of diabetic subjects at the common, bulb or internal carotid, respectively. Only 25% of patients had an HbA1c<7%, while over 41.6% presented with marked hyperglycemia (HbA1c>9%). The prevalence of diabetic subjects with abnormal levels of LDL-cholesterol, triglycerides, HDL-cholesterol or blood pressure was 45%, 16.6%, 15% and 65.7%, respectively.

Conclusions

Carotid thickness is increased in subjects with diabetes from a rural area of Cameroon, despite the relatively recent diagnosis. These findings and the high rate of uncontrolled diabetes in this population support the increasing concern of diabetes and cardiovascular diseases in African countries and indicate the need for multifaceted health interventions in urban and rural settings.     

Age-dependent relationship between the carotid intima-media thickness, baroreflex sensitivity, and the inter-beat interval in normotensive and hypertensive subjects

The interrelationship between baroreflex sensitivity expressed in ms/mm Hg (BRS) or in Hz/mm Hg (BRSf), carotid wall thickness (IMT), and age was investigated in hypertensive and normotensive subjects with respect to the mean inter-beat interval (IBI) and blood pressure (BP). BP monitoring was performed in 25 treated hypertensives (Hy; 47.4+/-9.2 years of age) and 23 normotensives (Norm; 44.5+/-8.1 years). IMT was measured by ultrasonography. BRS and BRSf were determined by the spectral method (five-minute non-invasive beat-to-beat recording of BP and IBI, Finapres, controlled breathing at a frequency of 0.33 Hz). Significant differences between Hy and Norm were detected in IMT (Hy: 0.624+/-0.183, Norm: 0.522+/-0.070 mm; p<0.01), BRS (Hy: 3.5+/-1.6, Norm: 5.7+/-2.3 ms/mm Hg; p<0.01), BRSf (Hy: 0.005+/-0.002, Norm: 0.009+/-0.004 Hz/mm Hg; p<0.01), systolic BP (Hy: 131+/-21, Norm: 116+/-17 mm Hg; p<0.01) and diastolic BP (Hy: 77+/-16, Norm: 64+/-12 mm Hg; p<0.01). A significant correlation was found between age and IMT (Norm: 0.523, p<0.05; Hy+Norm: 0.419, p<0.01), age and BRS (Norm: -0.596, p< 0.01; Hy+Norm: -0.496, p<0.01), age and BRSf (Norm: -0.555, p<0.01; Hy: -0.540, p <0.01; Hy+Norm: -0.627, p<0.01), age and IBI (Hy: 0.478, p<0.05), age and diastolic BP (Hy: -0.454, p<0.05), BRS and IMT (Hy+Norm: -0.327, p<0.05) and BRSf and IMT (Hy+Norm: -0.358, p<0.05). Hypertensive patients have increased IMT and decreased BRS and BRSf. The positive correlation between age and IMT and the negative correlation between age and BRS and BRSf are in agreement with the hypothesis that the age-dependent decrease of baroreflex sensitivity corresponds to the age-related structural changes of the carotid wall. Using two indices of baroreflex sensitivity, BRS and BRSf, we could show that baroreflex sensitivity in hypertensives is lower not only due to thickening of the carotid wall, but also due to aging.     

Relationship between adult height and body weight and risk of carotid atherosclerosis assessed in terms of carotid intima-media thickness: The Nagasaki Islands study

Background

Previous studies have reported an inverse association between height and risk of cardiovascular disease. However, evidence is limited for the association between risk of atherosclerosis and height. Further, although the association between atherosclerosis and body mass index (BMI) is reportedly positive, there have been no reports of studies on associations between height and atherosclerosis in relation to BMI.

Methods

We conducted a cross-sectional study of Japanese men aged 30 to 89 years undergoing general health check-ups.

Results

Of the 1,337 men, 312 were diagnosed with carotid atherosclerosis (carotid intima-media thickness (CIMT) ≥ 1.1 mm), but no significant association was found between height and carotid atherosclerosis for the entire study group. Stratification by BMI status of those analytical findings disclosed a significant inverse association between height and carotid atherosclerosis among overweight (BMI ≥ 25 kg/m²) but not among non-overweight (BMI < 25 kg/m²) men. The classical cardiovascular risk factors-adjusted odds ratio (OR) and 95% confidence interval (CI) of carotid atherosclerosis for an increment of one SD (standard deviation) in height (6.70 cm) were 0.71 (0.54 to 0.94) for overweight (BMI ≥ 25 kg/m²) and 1.05 (0.87 to 1.27) for non-overweight (BMI < 25 kg/m²) men.

Conclusion

Independent from classical cardiovascular risk factors, height was found to be inversely associated with carotid atherosclerosis for overweight but not for non-overweight men.     

Increased carotid artery intima-media thickness and myeloperoxidase level in children with newly diagnosed juvenile idiopathic arthritis

IntroductionJuvenile idiopathic arthritis (JIA) is a frequent childhood rheumatic disease characterized by chronic inflammation. The latter has been related to impairment of arterial functional-structural properties, atherogenesis and later cardiovascular events. The objective of this study was to examine intima-media thickness (IMT) and the parameters of arterial stiffness in children with JIA at diagnosis and their correlation with JIA subtype and markers of inflammation and atherosclerosis.MethodsThirty-nine newly diagnosed patients with JIA (26 girls; mean age, 13.2 ± 2.6 years) and 27 healthy controls (9 girls; mean age, 13.6 ± 3.4 years) were included in the study. Twelve patients had oligoarthritis, fifteen had extended oligoarthritis and twelve had rheumatoid factor–negative polyarthritis. IMT of the common carotid artery was determined by ultrasonography, carotid-femoral pulse wave velocity (cfPWV) and augmentation index adjusted to a heart rate of 75 beats/min (AIx@75) were determined by applanation tonometry. The serum levels of atherosclerosis-related biomarkers, such as asymmetric dimethylarginine (ADMA), myeloperoxidase (MPO) and adiponectin, were measured by enzyme-linked immunosorbent assay.ResultsMean IMT (0.46 ± 0.04 vs. 0.42 ± 0.04 mm; p = 0.0003) and MPO concentration (115.2 [95 % confidence interval {95 % CI}, 97.4–136.3] vs. 57.6 [95 % CI, 47.1–70.3] ng/ml; p < 0.0001) were higher in the patients with JIA than in the control subjects. The cfPWV, AIx@75 and serum ADMA and adiponectin levels did not significantly differ between the groups and JIA subtypes. Serum adiponectin level correlated negatively with AIx@75 in patients with JIA (r = −0.38; p < 0.05).ConclusionsPatients with JIA have increased mean IMT and elevated MPO levels at early stages of the disease. AIx@75 was inversely independently associated with adiponectin level in the patients, suggesting that lower adiponectin levels might influence arterial subclinical stiffening in patients with newly diagnosed JIA.     

Regular aerobic exercise and the age-related increase in carotid artery intima-media thickness in healthy men.

Carotid artery intima-media thickness (IMT), an independent risk factor for stroke, increases with age. Habitual exercise is associated with a lower prevalence of stroke, but it is unclear whether this protective effect could be mediated through a favorable influence on carotid IMT. We examined this possibility using both cross-sectional and intervention approaches. First, 137 healthy men (age 18-77 yr) who were either sedentary or endurance trained were studied. In both groups, carotid IMT and IMT-to-lumen ratio were progressively higher with age (P < 0.05). There were no significant differences in measures of carotid IMT between sedentary and endurance-trained men at any age. Carotid systolic blood pressure increased progressively with age and was related to carotid IMT (r = 0.63, P < 0.01). Second, 18 healthy sedentary subjects (54 +/- 2 yr) were studied before and after 3 mo of endurance training. Carotid IMT, IMT/lumen ratio, and carotid systolic blood pressure did not change with exercise intervention. Our results do not support the hypothesis that regular aerobic exercise exerts its protective effect against stroke by attenuating the age-related increase in carotid IMT. This lack of effect on carotid IMT may be due to the apparent inability of habitual exercise to prevent or reduce the age-associated elevation in carotid distending pressure.     

Carotid artery intima-media thickness, carotid plaque and coronary heart disease and stroke in Chinese

Background

Our aim was to prospectively investigate the association between carotid artery intima-media thickness (IMT) as well as carotid plaque and incidence of coronary heart disease (CHD) and stroke in Chinese, among whom data are limited.

Methods and Findings

We conducted a community-based cohort study composed of 2190 participants free of cardiovascular disease at baseline in one community. During a median 10.5-year follow up, we documented 68 new cases of coronary heart disease and 94 cases of stroke. The multivariate relative risks (RRs) associated with a change of 1 standard deviation of maximal common carotid IMT were 1.38 (95% confidence interval [CI], 1.12–1.70) for CHD and 1.47 (95% CI, 1.28–1.69) for stroke. The corresponding RRs with internal carotid IMT were 1.47 (95% CI, 1.21–1.79) for CHD and 1.52 (95% CI, 1.31–1.76) for stroke. Carotid plaque measured by the degree of diameter stenosis was also significantly associated with increased risk of CHD (p for trend<0.0001) and stroke (p for trend<0.0001). However, these associations were largely attenuated when adjusting for IMT measurements.

Conclusions

This prospective study indicates a significant association between carotid IMT and incidence of CHD and stroke in Chinese adults. These measurements may be useful for cardiovascular risk assessment and stratification in Chinese.     

Resistin and adiponectin levels in subjects with coronary artery disease and type 2 diabetes

BACKGROUND: Resistin and adiponectin are implicated in insulin resistance and atherosclerosis. The objective of this study was to evaluate the association between plasma resistin levels and the presence of coronary artery disease (CAD) or diabetes compared to the controls. In a cross-sectional study, we measured glucose, fasting lipid panel, resistin, adiponectin, insulin, C-reactive protein (CRP) and TNF-alpha in 57 subjects with CAD, 58 subjects with diabetes compared to 45 normal control subjects. Results: Subjects with CAD compared to the control subjects had increased insulin resistance index (39+/-32 vs. 13.45+/-12.73 with p<0.0001), CRP levels (3.8+/-4.03 vs. 2.0+/-2.0 with p<0.05) and decreased levels of adiponectin (12.5+/-4.8 vs. 17.26+/-10.4 with p<0.0003). Subjects with diabetes compared to the controls had had increased insulin resistance index (69+/-19 vs. 13.45+/-12.73 with p<0.001), CRP levels (4.1+/-4.8 vs. 2.0+/-2.0 with p<0.01) and decreased levels of adiponectin (11.58+/-4.8 vs. 17.26+/-10.4 with p<0.001). Compared to the controls, there was no significant difference in the levels of resistin in subjects with CAD (4.92+/-3.2 vs. 4.1+/-2.4) as well as diabetes (4.92+/-3.2 vs. 4.6+/-2.6). Both CRP and resistin levels correlate with TNF-alpha (r=0.557, p<0.000001; r=0.84, p<0.000001). Conclusions: The present study shows decreased plasma adiponectin levels in subjects with diabetes as well as in subjects with CAD is similar to the literature. Plasma levels of resistin in subjects with CAD or diabetes are similar to the controls. However, there was a strong correlation of resistin levels with inflammatory markers. This suggests resistin as an inflammatory marker associated with CAD.     

Progression of carotid artery disease could stratify a risk of coronary artery disease patients with type 2 diabetes

Diabetes is a common risk factor associated with coronary artery disease (CAD).Importantly,hereditary CAD cannot be discounted which accounts for about one quater of the cases [1].Carotid artery disease (CARD) shares the same risk factors as CAD [2].     

Relationship between changes in brachial artery flow-mediated dilation and basal release of nitric oxide in subjects with Type 2 diabetes

Assessment of flow-mediated dilation (FMD) after forearm ischemia is widely used as a noninvasive bioassay of stimulated nitric oxide (NO)-mediated conduit artery vasodilator function in vivo. Whether this stimulated endothelial NO function reflects basal endothelial NO function is unknown. To test this hypothesis, retrospective analysis of randomized crossover studies was undertaken in 17 subjects with Type 2 diabetes; 9 subjects undertook an exercise training or control period, whereas the remaining 8 subjects were administered an angiotensin II receptor blocker or placebo. FMD was assessed by using wall tracking of high-resolution brachial artery ultrasound images in response to reactive hyperemia. Resistance vessel basal endothelium-dependent NO function was assessed by using intrabrachial administration of NG-monomethyl-L-arginine (L-NMMA) and plethysmographic assessment of forearm blood flow (FBF). FMD was higher after intervention compared with control/placebo (6.15+/-0.53 vs. 3.81+/-0.72%, P<0.001). There were no significant changes in the FBF responses to L-NMMA. Regression analysis between FMD and L-NMMA responses at entry to the study revealed an insignificant correlation (r=-0.10, P=0.7), and improvements in FMD with the interventions were not associated with changes in the L-NMMA responses (r=-0.04, P=0.9). We conclude that conduit artery-stimulated endothelial NO function (FMD) does not reflect basal resistance vessel endothelial NO function in subjects with Type 2 diabetes.     

Carotid artery intima-media thickness is associated with insulin-mediated glucose disposal in nondiabetic normotensive offspring of type 2 diabetic patients

The aim of this study was to investigate whether insulin resistance is independently associated with early manifestations of atherosclerosis. To this end, 176 normotensive offspring of type 2 diabetic patients were subjected to euglycemic hyperinsulinemic clamp to assess insulin sensitivity. Early atherosclerosis was studied by ultrasonography of the common carotid artery. Of the total 176 subjects, 145 were glucose tolerant, 18 had impaired fasting glucose, and 13 had impaired glucose tolerance. Univariate correlations showed that age, body mass index, waist, blood pressure, 2-h postchallenge glucose, fasting insulin, triglycerides, interleukin-6, fibrinogen, and white blood cell count were significantly correlated with carotid intima-media thickness (IMT), whereas HDL cholesterol and glucose disposal showed a negative correlation. A stepwise multivariate regression analysis including sex, age, waist circumference, smoking status, systolic blood pressure, diastolic blood pressure, triglyceride, HDL cholesterol, 2-h postchallenge glucose, plasma IL-6, fibrinogen, white blood cell count, insulin-stimulated glucose disposal, and fasting insulin showed that the four variables that remained significantly associated with carotid IMT were waist circumference, insulin-stimulated glucose disposal, white blood cell count, and diastolic blood pressure, accounting for 33.7% of its variation. These findings support the concept that insulin sensitivity, rather than plasma insulin levels, is associated with early atherosclerosis in nondiabetic normotensive offspring of type 2 diabetic patients.     

Relationship between sleep duration and arterial stiffness in a multi-ethnic population: The HELIUS study

We examined the relationship between sleep duration and arterial stiffness among a multi-ethnic cohort, and whether the associations differed among ethnic minority groups in the Netherlands. Data were derived from 10 994 participants (aged 18–71 years) of the Healthy Life in an Urban Setting (HELIUS) study. Self-reported sleep duration was categorized into: short (<7 h/night), healthy (7–8 h/night) and long (≥9 h/night). Arterial stiffness was assessed by duplicate pulse-wave velocity (PWV in m/s) measurements using the Arteriograph system. The association of sleep duration with PWV was analysed using linear regression (β) with 95% confidence interval (CI). Results showed that neither short nor long sleep was related to PWV in all ethnic groups, except for long sleep in Dutch men which was associated with higher PWV (indicating stiffer arteries) after adjustment for potential confounders (β = 0.67, 95%CI, 0.23–1.11). Our study showed no convincing evidence that sleep duration was related to arterial stiffness among various ethnic groups. The link between sleep duration and cardiovascular outcomes does not seem to operate through arterial stiffness. Further research is needed to consolidate these findings.     

Remnant lipoproteins are related to intima-media thickness of the carotid artery independently of LDL cholesterol and plasma triglycerides

Remnants of triglyceride-rich lipoproteins (TRL) have been implicated in the early development of atherosclerosis. We tested this hypothesis by quantifying the plasma concentration of remnant-like particle cholesterol (RLP-C) in a cohort of healthy 50-year-old men in whom the common carotid artery intima-media thickness (CCA-IMT) was assessed by B-mode ultrasound as a surrogate marker for atherosclerosis. The subjects were given a fat-rich meal to study the generation of RLP-C during postprandial lipemia. Fasting plasma RLP-C and other major fasting plasma lipids and lipoproteins were determined twice, and the mean RLP-C concentration was strongly correlated with CCA-IMT (r = 0.32, P = 0.002). In addition, low density lipoprotein (LDL) cholesterol (r = 0.25, P = 0.01) and plasma triglycerides (r = 0.20, P = 0.05) were significantly related to CCA-IMT. Multivariate analyses showed a triglyceride-independent contribution of RLP-C to CCA-IMT. After fat intake, the median plasma RLP-C concentration was doubled after 3 h. The increase was strongly related to the postprandial generation of TRL apolipoprotein (apo)B-48, and large (S(f) 60;-400) TRL apoB-100. The association with CCA-IMT was somewhat stronger for the 3-h RLP-C level than for the fasting RLP-C concentration [r = 0.27, P < 0.01 (3 h) compared with r = 0.22, P < 0.05 (0 h)].We conclude that the plasma concentration of RLP-C is related to CCA-IMT, independent of plasma triglycerides and LDL cholesterol, in a healthy middle-aged male population. - Karpe, F., S. Boquist, R. Tang, G. M. Bond, U. de Faire, and A. Hamsten. Remnant lipoproteins are related to intima-media thickness of the carotid artery independently of LDL cholesterol and plasma triglycerides. J. Lipid Res. 2001. 42: 17;-21.     

Association between OLR1 K167N SNP and intima media thickness of the common carotid artery in the general population

Background and Purpose

The lectin-like oxidised LDL receptor-1 (OLR1) gene encodes a scavenger receptor implicated in the pathogenesis of atherosclerosis. Although functional roles have been suggested for two variants, epidemiological studies on OLR1 have been inconsistent. Methods - We tested the association between the non-synonymous substitution K167N (rs11053646) and intima media thickness of the common carotid artery (CCA-IMT) in 2,141 samples from the Progression of Lesions in the Intima of the Carotid (PLIC) study (a prospective population-based study).

Results

Significantly increased IMT was observed in male carriers of the minor C (N) allele compared to GC and GG (KN and KK) genotype. Functional analysis on macrophages suggested a decreased association to Ox-LDL in NN carriers compared to KN and KK carriers which is also associated with a reduced OLR1 mRNA expression. Macrophages from NN carriers present also a specific inflammatory gene expression pattern compared to cells from KN and KK carriers.

Conclusions

These data suggest that the 167N variant of LOX-1 receptor affects the atherogenic process in the carotid artery prior to evidence of disease through an inflammatory process.     

Correlation between quantitative analysis of wall shear stress and intima-media thickness in atherosclerosis development in carotid arteries

Background

This paper presents quantitative analysis of blood flow shear stress by measuring the carotid arterial wall shear stress (WSS) and the intima-media thickness (IMT) of experimental rabbits fed with high-fat feedstuff on a weekly basis in order to cause atherosclerosis.

Methods

This study is based on establishing an atherosclerosis model of high-fat rabbits, and measuring the rabbits’ common carotid arterial WSS of the experimental group and control group on a weekly basis. Detailed analysis was performed by using WSS quantification.

Results

We have demonstrated small significant difference of rabbit carotid artery WSS between the experimental group and the control group (P<0.01) from the 1st week onwards, while the IMT of experimental group had larger differences from 5th week compared with the control group (P<0.05). Next, we have shown that with increasing blood lipids, the rabbit carotid artery shear stress decreases and the rabbit carotid artery IMT goes up. The decrease of shear stress appears before the start of IMT growth. Furthermore, our receiver operator characteristic (ROC) curve analysis showed that when the mean value of shear stress is 1.198 dyne/cm², the rabbit common carotid atherosclerosis fatty streaks sensitivity is 89.8%, and the specificity is 81.3%. The area under the ROC curve is 0.9283.

Conclusions

All these data goes to show that WSS decreasing to 1.198 dyne/cm² can be used as an indicator that rabbit common carotid artery comes into the period of fibrous plaques. In conclusion, our study is able to find and confirm that the decrease of the arterial WSS can predict the occurrence of atherosclerosis earlier, and offer help for positive clinical intervention.

     

AMPK activity and isoform protein expression are similar in muscle of obese subjects with and without type 2 diabetes

Acute or chronic activation of AMP-activated protein kinase (AMPK) increases insulin sensitivity. Conversely, reduced expression and/or function of AMPK might play a role in insulin resistance in type 2 diabetes. Thus protein expression of the seven subunit isoforms of AMPK and activities and/or phosphorylation of AMPK and acetyl-CoA carboxylase-beta (ACCbeta) was measured in skeletal muscle from obese type 2 diabetic and well-matched control subjects during euglycemic-hyperinsulinemic clamps. Protein expression of all AMPK subunit isoforms (alpha1, alpha2, beta1, beta2, gamma1, gamma2, and gamma3) in muscle of obese type 2 diabetic subjects was similar to that of control subjects. In addition, alpha1- and alpha2-associated activities of AMPK, phosphorylation of alpha-AMPK subunits at Thr172, and phosphorylation of ACCbeta at Ser221 showed no difference between the two groups and were not regulated by physiological concentrations of insulin. These data suggest that impaired insulin action on glycogen synthesis and lipid oxidation in skeletal muscle of obese type 2 diabetic subjects is unlikely to involve changes in AMPK expression and activity.