Insulin-sensitizing effects of exercise on adiponectin and retinol-binding protein-4 concentrations in young and middle-aged women

CONTEXT: Exercise training enhances insulin sensitivity. Changes in retinol-binding protein-4 (RBP4) and adiponectin levels are linked to insulin resistance. OBJECTIVE: We tested whether the insulin-sensitizing effect of exercise is associated with age-related changes in circulating RBP4 and adiponectin levels in women. DESIGN, SUBJECTS, AND INTERVENTION: We studied 36 healthy young (22.4 +/- 2.8 yr) and 38 middle-aged (59.8 +/- 5.9 yr) women. All subjects performed 60 min of aerobic exercise three times per week for 10 wk at about 70% maximal exercise capacity. RESULTS: After a 10-wk training program, maximal exercise capacity was significantly increased in both young and middle-aged women, suggesting increased oxidative capacity. Insulin sensitivity was also improved, as indicated by decreases in plasma insulin levels and homeostasis model assessment for insulin resistance index. Serum adiponectin and RBP4 concentrations were increased and decreased more in older than younger women, respectively (P < 0.01). Concurrently, circulating transthyretin levels were also decreased in older subjects in response to exercise training. The older women showed higher correlations between changes in adiponectin or RBP4 levels and obesity indices or metabolic parameters than the younger group. When subjects showing increasing adiponectin or decreasing RBP4 levels were classified as responders, there were higher correlations between these changes in responders than in nonresponders. CONCLUSIONS: We conclude that the mechanism for the insulin-sensitizing effects of exercise could involve increased adiponectin and reduced RBP4 levels in exercise-trained women. These data suggest that alterations in circulating RBP4 and adiponectin levels could play an important role in regulating insulin sensitivity.     

High plasma retinol binding protein-4 and low plasma adiponectin concentrations are associated with severity of glucose intolerance in women with previous gestational diabetes mellitus

CONTEXT: Women with previous gestational diabetes mellitus (pGDM) are at high risk of developing type 2 diabetes mellitus in the future. The role of adipokines in women with pGDM has not been established. OBJECTIVE: We investigated whether circulating adipokine concentration is associated with abnormal glucose homeostasis in women with pGDM. DESIGN, SETTING, PATIENTS, AND MAIN OUTCOME MEASURES: We measured the plasma concentrations of retinol-binding protein-4 (RBP4), transthyretin (TTR), and adiponectin and metabolic parameters in four groups of women who exhibited normal glucose tolerance (NGT) during a previous pregnancy (NP, n = 17), NGT after GDM (GDM-NGT, n = 72), impaired glucose tolerance after GDM (GDM-IGT, n = 60), and type 2 diabetes after GDM (GDM-DM, n = 8). RESULTS: Plasma RBP4 concentration was significantly higher in women with GDM-DM, GDM-IGT, and GDM-NGT than in those with NP. RBP4 concentration correlated positively with TTR concentration; fasting plasma glucose, insulin, and triglyceride concentrations; blood pressure; abdominal fat area; and homeostasis model assessment of insulin resistance. Plasma TTR concentration was elevated in women with GDM-DM compared with other groups. In contrast, adiponectin concentration was lowest in the GDM-DM group and correlated inversely with parameters of insulin resistance. Resistin concentration was higher only in the GDM-NGT and GDM-IGT groups, whereas leptin did not differ between groups. Plasma RBP4 and adiponectin concentrations were inversely correlated. CONCLUSIONS: The severity of glucose intolerance in women with pGDM is associated with high RBP4 and low adiponectin concentrations.     

Effect of exercise training on the untrained limb exercise performance of men with angina pectoris

This study examined the exercise capacity of trained and untrained limbs in men with angina pectoris before and after 8 weeks of arm (n = 4) or leg (n = 7) physical training or a control (n = 4) period. Time to angina (mean ± standard deviation) increased 3.6 ± 2.7 minutes (p < 0.01) during trained limb and 1.6 ± 1.2 minutes (p < 0.01) during untrained limb exercise. Myocardial oxygen demand at angina estimated by the product of heart rate and systolic blood pressure did not change with training. At a constant subanginal work load, rate-pressure product × 10^?2 was reduced by 35 ± 22 (p < 0.001) during trained limb and by 18 ± 27 (p < 0.05) during untrained limb exercise. The decrease in rate-pressure product with both trained and untrained limbs was greatest in subjects with the highest rate-pressure product at angina before training. Control subjects showed no change in any exercise measurement.Exercise training increases the exercise capacity of untrained limbs in patients with angina pectoris by a generalized training effect not dependent on adaptations In trained skeletal muscle. The improvement for both trained and untrained limbs results from a reduced rate-pressure product at subanginal work loads rather than from an increase in myocardial oxygen delivery. Subjects with the highest pretraining coronary arterial oxygen supply at the onset of angina benefit most from physical training.     

Time course responses of serum GH, insulin, IGF-1, IGFBP1, and IGFBP3 concentrations after heavy resistance exercise in trained and untrained men

To investigate the effect of heavy resistance exercise on IGF-1 system, 19 healthy trained men and 15 healthy untrained men volunteered to participate in this study. The subjects were randomly divided into experimental and control groups. Subjects of experimental groups were forced to perform a heavy resistance exercise with the intensity of 70-80% of 1RM in selected movements. The blood samples were taken from all subjects four times; before (T1), immediately after (T2), 5 (T3), and 8 (T4) hours after exercise. Analysis of data showed that a session of heavy resistance exercise induced significant increase in GH at T2 (P < 0.05) and a significant decrease in insulin at T4 (P < 0.05) and a significant decrease in IGFBP3 at T4 (P < 0.05) in trained group. In untrained group, no significant change in any of the variables was observed. However, the procedure of response in variables was almost similar in two experimental groups. Although, the exercise did not appreciably affect IGF-1 levels, it decreased in all groups at length of time after exercise. In addition, the exercise did not have any notable effect on IGFBP1 levels over time. In conclusion, the findings of this study indicate that the intense resistance exercise can lead to changes in blood concentrations of IGF-1 system components which are observable in blood circulation over time and the amounts of changes depend on subjects' fitness levels and exercise variables.     

Association of insulin resistance with anti-Mullerian hormone levels in women without polycystic ovary syndrome (PCOS)

Objective  To explore the relationship of insulin resistance (IR) and adipokines (leptin, adiponectin, RBP4) to anti-Mullerian hormone (AMH) levels in women without polycystic ovary syndrome (PCOS).
Design/patients/measurements  We recruited 120 healthy, reproductive age women without PCOS. An overnight fasting blood draw, anthropometric measurements, analyses of serum levels of AMH, adipokines (leptin, adiponectin and RBP4) and total testosterone, a homeostasis model assessment for insulin resistance (HOMA-IR) and a transvaginal ultrasound scan were performed between the third and fifth day of their spontaneous menstrual cycles.
Results  Higher HOMA-IR levels were associated with lower levels of AMH. After adjustment for age, serum AMH levels negatively correlated with insulin, fasting glucose, HOMA-IR and RBP4. However, a positive correlation was identified between serum AMH and adiponectin. A final multiple stepwise linear regression demonstrated that HOMA-IR was independently associated with AMH.
Conclusion  An independent relationship exists between HOMA-IR and AMH in women without PCOS, possibly due to the effect of abnormal insulin action on AMH secretion by granulosa cells.     

Increased plasma levels of retinol‐binding protein 4 with visceral obesity is associated with cardiovascular risk factors

Aims/Introduction: Visceral obesity has been suggested to be an independent risk factor for cardiovascular disease (CVD); the role of adipokines in the risk for CVD is less clear. Aim of this study was to investigate the relationship between parameters of visceral obesity and index of CVD risk factors. Materials and Methods: A cross‐sectional analysis of healthy males (n = 116) and females (n = 175) for evaluation of clinical, laboratory and anthropometric parameters were undertaken. Abdominal subcutaneous (SAT) and visceral adipose tissues (VAT) were measured by computed tomography. Adipokines, including retinol‐binding protein 4 (RBP4) and adiponectin, were determined. The risk for CVD was estimated using the 10‐year Framingham Coronary Heart Disease Risk Point scale (Framingham score). Results: The Framingham score was increased in subjects with metabolic syndrome, and significantly increased with various indices of obesity, traditional risk factors of CVD, C‐reactive protein (CRP) and RBP4, but decreased with adiponectin. With multiple linear regression analysis, the Framingham score independently associated with age, smoking status, body mass index, triglyceride and RBP4. The magnitude of the Framingham score showed a linear trend of increase with CRP, VAT and RBP4 (all P < 0.001), but of decrease with SAT and adiponectin (all P < 0.05) at stratified levels of obesity. Conclusions: RBP4 is increased with visceral fat accumulation and associated with CVD risk factors independent of obesity or traditional risk factors. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2012.00213.x , 2012)     

Effect of exercise training combined with phytoestrogens on adipokines and C-reactive protein in postmenopausal women: a randomized trial

Phytoestrogens and training could be effective to reduce cardiovascular and type 2 diabetes mellitus risk factors in postmenopausal women. Nevertheless, the impact of their combination on adipokines and systemic inflammation was never investigated. The objective was to verify if 6 months of mixed training combined with phytoestrogens could have an additional effect on adipokine levels and systemic inflammation in obese postmenopausal women. Fifty-two obese women aged between 50 and 70 years were randomly assigned to (1) exercise with placebo (EX + PL; n = 25) or (2) exercise with phytoestrogens (EX + PHY; n = 27). Body weight, waist circumference, fat mass, and lean body mass (dual-energy x-ray absorptiometry) were assessed. Fasting plasma glucose and insulin, adiponectin, leptin, and C-reactive protein (CRP) levels were obtained after a 12-hour overnight fast. Total energy intake was measured with a 3-day dietary record. All measurements were performed before and after the 6-month intervention. Although energy intake remained unchanged, body composition was improved in all women (all Ps < .02). Plasma CRP and leptin levels decreased in both groups similarly (all Ps < .03), whereas plasma adiponectin and insulin did not change with exercise combined with placebo or phytoestrogens. Correlation analyses showed that homeostasis model assessment of insulin resistance (r = -0.58, P = .02) and fasting insulin levels (r = -0.42, P = .02) at baseline were both correlated with changes in leptin levels. Baseline fasting glucose (r = -0.36, P = .03) and adiponectin (r = 0.45, P = .005) levels were associated with changes in CRP concentrations. Although mixed exercise program combined with phytoestrogens does not seem to provide any additional effect, mixed training improves systemic inflammation and leptin concentrations in obese postmenopausal women.     

Serum retinol binding protein 4 and nonalcoholic fatty liver disease in patients with type 2 diabetes mellitus

Retinol binding protein 4 (RBP4) is a protein secreted by adipocytes, and closely associated with insulin resistance. Whereas RBP4 is also mainly expressed in hepatocytes as the principal transport protein for retinol (vitamin A) in the circulation, and its pathophysiological role in liver remain unclear. The aim of this paper was to investigate the association between RBP4 and nonalcoholic fatty liver disease (NAFLD) in patients with type 2 diabetes mellitus (T2DM). Serum RBP4 and adiponectin concentrations were measured by radioimmunoassay in 52 diabetic patients who had NAFLD and 50 sex- and age-matched diabetic patients without any clinical features of liver diseases who had normal liver ultrasonic appearance and normal liver function. Serum RBP4 levels were elevated in diabetic patients with NAFLD (32.0+/-8.9 microg/ml vs. 41.3+/-9.8 microg/ml, p<0.001), while adiponectin decreased (17.4+/-9.3 microg/ml vs. 13.8+/-7.0 microg/ml, p=0.032). Male diabetic patients had higher serum RBP4 concentration and lower serum adiponectin concentration than female diabetic patients (38.5+/-9.9 microg/ml vs. 34.0+/-10.7 microg/ml, p=0.031 and 12.7+/-5.7 microg/ml vs. 20.23+/-9.8 microg/ml, p<0.001, respectively). Multiple logistic regression analysis revealed RBP4 and triglyceride as independent association factors for NAFLD, while the association between serum adiponectin and NAFLD was not significant. Increasing concentrations of RBP4 were independently and significantly associated with NAFLD in diabetic patients. In multiple linear regression analysis, alanine aminotransferase, fasting serum insulin and adiponectin were independent factors for serum RBP4 level. The study demonstrates that retinol binding protein 4 might contribute to the pathogenesis of nonalcoholic fatty liver disease.     

Use of muscle functional magnetic resonance imaging with older individuals

Muscle functional magnetic resonance imaging (mfMRI) has been widely used to study muscle recruitment in exercise in young healthy subjects, but has not been validated or used with older subjects. This study validates and demonstrates the use of mfMRI in older subjects. Subjects consisted of apparently healthy sedentary younger (n = 7) and older (n = 6) women. Proton transverse relaxation (T2)-weighted MRI scans were obtained of the quadriceps femoris at rest and immediately following three bouts of knee extension exercise (50%, 75%, and 100% of untrained 5 x 10 repetition maximum [RM]). Older subjects performed knee extension training for 12 weeks and repeated the MRI scan protocol using the same absolute loads. Training induced a 13% increase in 1 RM and a 25% increase in 5 x 10 RM. Older subjects had higher resting T2 values compared with younger subjects; however, the T2 response to exercise (slope) was similar among groups (young = 0.063+/-0.003, older untrained = 0.055+/-0.011, older trained = 0.053+/-0.008; p > .05). In all cases, T2 increased linearly with load. Trained older subjects showed a lower T2 response when lifting the same absolute load compared with before training, which is consistent with results previously obtained from young subjects. In the older population, mfMRI is appropriate for use and offers benefits over other technologies.     

Effects of home-based exercise training on neurovascular control in patients with heart failure

BACKGROUND: The effect of home-based exercise training on neurovascular control in heart failure patients is unknown. AIMS: To test the hypothesis that home-based training would maintain the reduction in muscle sympathetic nerve activity (MSNA) and forearm vascular resistance (FVR) acquired after supervised training. METHODS AND RESULTS: Twenty-nine patients (54+/-1.9 years, EF<40%) were randomised into two groups: untrained control (n=12) and exercise trained (n=17). Both groups underwent assessment of Quality of Life (QoL), MSNA, and forearm blood flow. The exercise group underwent a 4-month supervised training program followed by 4 months of home-based training. After the initial 4 months of training, patients in the exercise group showed a significant increase in peak VO(2) and reduction in MSNA, compared to the untrained group, but this was not maintained during 4 months of home-based training. In contrast, the decrease in FVR (56+/-3 vs. 46+/-4 vs. 40+/-2 U, p=0.008) and the improvement in QOL that were achieved during supervised training were maintained during home-based training. CONCLUSIONS: Home-based training following supervised training is a safe strategy to maintain improvements in QoL and reduction in FVR in chronic heart failure patients, but is an inadequate strategy to maintain fitness as estimated by peak VO(2) or reduction in neurohumoral activation.     

Adiponectin and C-reactive protein in obesity, type 2 diabetes, and monodrug therapy

To learn more about the factors that regulate adipokines in diabetes, we examined fasting plasma concentrations of adiponectin and C-reactive protein (CRP) in well-characterized groups of age-matched individuals classified as: (1) type 2 diabetes; (2) impaired fasting glucose or mild diabetes (IFG/mild DM); (3) obese, matched for body mass index (BMI); and (4) non-obese. Diabetic subjects were also studied on no phamacologic treatment, after 3 months randomization to metformin or glyburide, and after 3 months crossover to the opposite drug. CRP decreased and adiponectin increased progressively between subjects in groups 1 through 4. CRP was significantly associated with percent (r = 0.45) and total (r = 0.50) fat, insulin sensitivity as S(I) (r = -0.39) or homeostasis model assessment of insulin resistance [HOMA (IR)] (r = -0.36), and hemoglobin A(1c) (HbA(1c)) (r = 0.41). The relationship of CRP to percent fat appeared to be logarithmic and log CRP varied with percent fat independent of gender. Adiponectin concentration was significantly associated with insulin sensitivity as S(I) (r = 0.55) or HOMA (IR) (r = -0.46). Adiponectin concentrations were higher among women overall (all groups included) but not in women classified as type 2 diabetes. Although mean adiponectin was higher in subjects classified as non-obese compared to obese, adiponectin, in sharp contrast to leptin (previously reported data) and to CRP, varied markedly when expressed as a function of adiposity. Multiple regression models confirmed the strong relationship of adiponectin to insulin sensitivity, as well as the relationships of CRP to adiposity and insulin sensitivity. Glyburide treatment of diabetes decreased CRP and did so even though body weight increased. We conclude that both CRP and adiponectin correlate strongly to S(I). CRP, in contrast to adiponectin, is far more dependent on adiposity. The relationship between CRP (like leptin) and gender depends on how CRP is expressed relative to adiposity. Our data raise the possibility that gender differences in adiponectin may be lost in diabetes. Finally, pharmacologic treatment of diabetes may modulate CRP independent of adiposity.     

Effects of prolonged intensive versus moderate leg training on the untrained arm exercise response in angina pectoris

To compare the effects of 2 different leg training intensities on the cardiocirculatory exercise response of the untrained arm, 58 patients with angina pectoris were randomized to either an intensive (at least 85% of symptom-limited exercise, n = 28) or a moderate (70 to 85% of symptom-limited exercise, n = 30) training group. Patients trained for 6 months, 2 times per week for 30 minutes each. Results of the 2 groups after training showed similar significant (p less than or equal to 0.001) decreases in heart rate (HR), systolic blood pressure (BP) and HR X BP product for trained legs and untrained arms at matched subanginal workloads and significant (p less than 0.01 to 0.001) increase in anginal threshold HR and HR X BP for the onset of 1 mm or more ST horizontal depression during testing of trained legs as well as of untrained arms. The improvement in exercise capacity at subanginal workloads results from decreased HR X BP product. In contrast, the significant increase in HR X BP product for the onset of ST-segment displacement and precipitation of anginal pain for both the trained and untrained limbs may imply an increase in myocardial blood flow. Thus, prolonged intensive or moderate training may significantly improve coronary blood flow in selected patients with angina pectoris. Patients with the highest anginal threshold HR and HR X BP product before training showed the most improvement at 6 months after training.     

Comparison of 24-hour parasympathetic activity in endurance-trained and untrained young men.

OBJECTIVES. This study compares 24-h parasympathetic activity in aerobically trained and untrained healthy young men. BACKGROUND. Higher values of parasympathetic nervous system activity are associated with a low mortality rate in patients after myocardial infarction, but it remains uncertain what therapeutic interventions can be used to increase parasympathetic activity. Although it is thought that exercise training can increase parasympathetic activity, studies have reported conflicting results, perhaps because this variable was measured for only brief intervals and usually inferred from changes in reflex responses induced by pharmacologic blockade. METHODS. Parasympathetic activity was assessed noninvasively from 24-h ECG recordings by calculating high frequency (0.15 to 0.40 Hz) beat to beat heart period variability in eight endurance-trained men (maximal oxygen consumption greater than or equal to 55 ml/kg per min) and eight age-matched (mean = 29 yr) untrained men (maximal oxygen consumption less than or equal to 40 ml/kg per min). The data were analyzed separately for sleeping hours when parasympathetic activity is dominant and also for waking hours. RESULTS. The geometric mean of high frequency power was greater in the trained than in the untrained men during the day (852 vs. 177 ms2, p less than 0.005), during the night (1,874 vs. 427 ms2, p less than 0.005) and over the entire 24 h (1,165 vs. 276 ms2, p less than 0.001). CONCLUSIONS. Parasympathetic activity is substantially greater in trained than in untrained men, and this effect is present during both waking and sleeping hours. These data suggest that exercise training may increase parasympathetic activity over the entire day and may therefore prove to be a useful adjunct or alternative to drug therapy in lessening the derangements of autonomic balance found in many cardiovascular diseases.     

Acute decrease in serum triglycerides with exercise: Is there a threshold for an exercise effect?

Acute reductions in triglycerides and low density lipoprotein (LDL) cholesterol concentrations have been demonstrated in endurance athletes after prolonged exercise. To determine if similar changes occur in untrained subjects and to determine the duration of exercise necessary for such changes, we measured serum lipids and lipoproteins in 10 sedentary men after 1 hour of exercise at their anaerobic threshold. Findings in sedentary men were compared with those of 9 competitive cyclists after 1 and 2 hr of exercise. LDL cholesterol increased in the cyclists immediately after 1 and 2 hours of exercise. Total cholesterol and high density lipoprotein (HDL) cholesterol also increased in the cyclists immediately after the 2 hr session. These increases were transient and not significant when corrected for changes in plasma volume. Serum triglycerides were unchanged for 4 hr after exercise. By 24 hr, however, triglycerides had decreased in both the trained (17%) and untrained men (22%) after the 1 hr session and in the trained men (33% p < 0.01) after the 2 hr session. These results demonstrate a delayed decrease in triglyceride concentration that is related to the duration of exercise and probably has no distinct threshold. The lower level of triglycerides in endurance athletes and in sedentary subjects after exercise training is due at least in part to an acute exercise effect.     

Associations Between Antioxidant Vitamin Status,Dietary Intake,and Retinol-binding Protein 4 Levels in Prepubertal Obese Children After 3-month Weight Loss Therapy

Objective:Adiposity is associated with increased oxidative stress, leading to changed fat-soluble vitamin concentrations. The aim of this study was to determine whether weight loss alters fat-soluble vitamin status and whether these alterations are associated with dietary intake, anthropometric parameters and adipokines in obese children.Methods:Vitamin A and E concentrations were measured using high-pressure liquid chromatography in 60 obese children before and after weight loss therapy. Retinol-binding protein 4 (RBP4), leptin, soluble leptin receptor (sOB-R), and high molecular weight adiponectin concentrations were determined by immunoenzymatic assays.Results:The intake of vitamin E was lower in obese children with weight loss after therapy (p=0.038). In this group, an increase was found in the vitamin A/lipids (p=0.022) and the vitamin E/lipids (p=0.008) ratios but due to the reduction in triglyceride levels. In the obese group, changes in vitamin E level were positively correlated with changes in dietary vitamin E (p=0.017) and the leptin/sOB-R ratio (p=0.046). Changes in vitamin A level were positively correlated with changes in dietary vitamin A (p=0.001) and RBP4 concentration (p=0.023). Associations between changes in RBP4 level with the changes in body mass index (BMI) (p=0.011) and total cholesterol concentration (p=0.023) but not with changes in vitamin A concentration were found in the obese after therapy.Conclusion:An increased risk of vitamin E deficiency may occur in children losing weight during lifestyle intervention. Changes in BMI value may influence changes in RBP4 concentrations and consequently the vitamin A status in obese children after therapy.     

Skeletal muscle satellite cell characteristics in young and older men and women after heavy resistance strength training

Skeletal muscle satellite cell proportions and morphology were assessed in healthy, sedentary young and older men and women in response to heavy resistance strength training (HRST). Fourteen young (20-30 years) men (n = 7) and women (n = 7) and 15 older (65-75 years) men (n = 8) and women (n = 7) completed 9 weeks of unilateral knee extension exercise training 3 days per week. Muscle biopsies were obtained from each vastus lateralis before and after training, with the nondominant leg serving as an untrained control. All four groups demonstrated a significant increase in satellite cell proportion in response to HRST (2.3 +/- 0.4% vs 3.1 +/- 0.4% for all subjects combined, before and after training, respectively; p < .05), with older women demonstrating the greatest increase (p < .05). Morphology data indicated a significant increase in the proportion of active satellite cells in after-training muscle samples compared with before-training samples and with control leg samples (31% vs 6% and 7%, respectively; p < .05). The present results indicate that the proportion of satellite cells is increased after HRST in young and older men and women, with an exaggerated response in older women. Furthermore, the proportion of satellite cells that appear morphologically active is increased as a result of HRST.     

The effect of residential exercise training on baroreflex control of heart rate and sympathetic nerve activity in patients with acute myocardial infarction

STUDY OBJECTIVES: Exercise training has been shown to favorably affect the prognosis after acute myocardial infarction (AMI), but the mechanisms of such favorable effects remain speculative. The aim of this study was to determine whether exercise training improves baroreflex control of heart rate and muscle sympathetic nerve activity (MSNA) in patients with AMI. DESIGN: Prospective randomized clinical study. PARTICIPANTS: Thirty patients with an uncomplicated AMI were randomized into trained or untrained groups. Arterial BP, heart rate, and MSNA were measured at rest, and during baroreceptor stimulation (phenylephrine infusion) and baroreceptor deactivation (nitroprusside infusion). These measurements were performed at baseline and after 4 weeks of exercise training. MEASUREMENTS AND RESULTS: Peak oxygen uptake increased significantly (12.3 +/- 10.7% [mean +/- SD]) with exercise training. Resting MSNA reduced from 34 +/- 12 to 27 +/- 8 bursts/min in the trained group but not in the untrained group. Arterial baroreflex sensitivity (BRS) [from 8.9 +/- 3.0 to 10.3 +/- 3.0 ms/mm Hg, p < 0.05] and MSNA response to baroreceptor stimulation (change of integrated MSNA from - 47 +/- 23 to - 70 +/- 21%, p < 0.01) improved significantly in the trained group, but not in the untrained group. Despite baroreceptor deactivation improving MSNA response in both groups, there was no significant difference between the two groups. CONCLUSIONS: Exercise training increased arterial BRS and decreased sympathetic nerve traffic after AMI, which indicate that the sympathoinhibitory effect of exercise training may, at least in part, contribute to the beneficial effect of exercise training in patients with AMI.     

Adipokines in type 1 diabetes after successful pancreas transplantation: normal visfatin and retinol‐binding‐protein‐4, but increased total adiponectin fasting concentrations

Objective In type 1 diabetes mellitus (T1DM), the release of many hormones, not only from beta‐cells, but also from adipocytes (adipokines) may be altered. After successful pancreas–kidney‐transplantation (PKTx), T1DM patients can revert to a nondiabetic metabolism, but it is unclear whether alterations of adipokines are still present after PKTx. Design, patients and measurements Concentrations of adipokines [visfatin, retinol‐binding protein‐4 (RBP‐4), adiponectin, high molecular weight (HMW) adiponectin] were measured at fasting in 10 PKTx and in 19 T1DM. Nondiabetic healthy controls (CON, n = 9) and six nondiabetic patients after kidney transplantation (KTx) were examined as control groups. In PKTx, KTx and CON, indices of insulin sensitivity (OGIS) and beta cell function (adaptation index, AI) were calculated from 75 g oral glucose tolerance test (OGTT) data. Results Fasting serum visfatin (T1DM: 56 ± 4 μg/l, PKTx: 42 ± 6 μg/l, KTx: 39 ± 3 μg/l, CON: 40 ± 3 μg/l) and RBP‐4 (T1DM: 490 ± 26 μg/l, PKTx: 346 ± 39 μg/l, KTx: 401 ± 13 μg/l, CON: 359 ± 36 μg/l) was increased by 40% and 36%, respectively (each P < 0·03) in T1DM only. Levels were positively correlated with HbA1c in all subjects (visfatin: r = 0·43, P < 0·004; RBP‐4: r = 0·46, P < 0·03). Fasting plasma adiponectin was 80% higher in T1DM and in PKTx (T1DM: 18 ± 2 mg/l, PKTx: 18 ± 3 mg/l, KTx: 12 ± 3 mg/l, CON: 10 ± 1 mg/l; P < 0·04) and was positively correlated with diabetes duration (r = 0·37, P < 0·02). HMW/total adiponectin ratio was increased in T1DM (P < 0·02). PKTx displayed a normoglycaemic metabolism as insulin sensitive as CON, but AI was lower than in CON and KT (P < 0·01). Conclusions T1DM after successful PKTx show normal fasting visfatin and RBP‐4 levels and HMW‐adiponectin/adiponectin‐ratio, which are elevated in T1DM, whereas total adiponectin levels are similarly increased in T1DM and PKTx patients.     

Inverse association between adiponectin and C-reactive protein in substantially healthy Japanese men

OBJECTIVE: An inverse association between adiponectin and C-reactive protein (CRP) has been shown in certain pathological states including obesity, diabetes, and coronary artery disease, which themselves might have confounded this association. This study investigated the association between adiponectin and CRP among substantially healthy subjects. METHODS AND RESULTS: A population of 2347 middle-aged Japanese men with no medical history of cardiovascular disease, cancer, diabetes, hypertension, or hyperlipidemia was evaluated. Those with some metabolic syndrome components from serological and anthropometric tests were excluded, leaving 714 men for analysis. Serum adiponectin and CRP were significantly correlated (r = -0.21, P < 0.001). After categorization into quartiles from the lowest to the highest adiponectin concentration (Q1 to Q4), the CRP level was found to be significantly higher in Q1 than in Q2, Q3 and Q4 (0.41 mg/L versus 0.30, 0.25 and 0.24 mg/L, P = 0.043, P < 0.001 and P < 0.001, respectively). These associations remained significant even after adjustment for covariates. Moreover, multiple linear regression analysis revealed that adiponectin contributed more strongly to CRP than other factors, including the index of insulin resistance. CONCLUSIONS: An inverse and strong association between adiponectin and CRP in substantially healthy subjects implies that decreased serum adiponectin might be fundamentally associated with the early stage of low-grade inflammation.     

Adiponectin and insulin resistance in young and healthy smokers

Smoking is closely associated with insulin resistance, though the mechanism is not clear. Adiponectin, a novel anti-atherosclerotic and anti-inflammatory adipose tissue product, which is closely associated with insulin resistance, was reported to be low in smokers with cofactors for atherosclerosis. However, the effects of smoking on circulating adiponectin levels in otherwise healthy people are unknown. In this study, a case control design was implemented to search for the effect of smoking on plasma adiponectin and insulin sensitivities in healthy people. Sixty-four healthy male smokers, with no family history of hypertension and diabetes mellitus were compared with appropriate 36 age and body mass index matched controls. Both the patients and controls were the soldiers of a troop with regular daily physical activity. Plasma adiponectin, high sensitive C-reactive protein (hsCRP), insulin and lipid levels, and insulin sensitivity as assessed by homeostasis model assessment index (HOMA) of the smokers were measured and compared with those of the controls. The plasma adiponectin, hsCRP, insulin levels and HOMA indexes of the two groups were similar. These parameters were not affected by the amount of cigarettes per day. HDL-cholesterol levels were lower (p = 0.01) and systolic blood pressures were higher (p = 0.02) in the smokers. These results indicate that smoking may not affect plasma adiponectin and insulin levels in young and healthy men with high exercise capacity.