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Biomedical subjects

A Nadeau

Publications and source records attributed to A Nadeau.

At least 91 records · Page 5Linked to original sources

Post-exercise reduction in blood pressure in hypertensive subjects: effects of angiotensin converting enzyme inhibition.

1. Much attention has been given to the effects of various classes of antihypertensive drugs on blood pressure and haemodynamics. The effects of a single bout of exercise on post-exercise blood pressure have also been studied by several investigators. However, the combined effects of prior exercise and antihypertensive medication has drawn less attention. 2. We examined the separate and combined effects of a single bout of exercise and of angiotensin converting enzyme (ACE) inhibition with a new ACE inhibitor (fosinopril, 20 mg day(-1)) on post-exercise blood pressure and systemic and regional haemodynamics. Ten patients with mild-to-moderate hypertension were studied with a double-blind, randomized crossover, placebo- and rest period-controlled study design. 3. At rest, mean arterial pressure (MAP, -10 +/- 2 mm Hg), total peripheral resistance (TPR, -11 +/- 5%) and forearm vascular resistance (FVR, -17 +/- 8%) were significantly (P < 0.05) reduced during ACE inhibition as compared with the placebo phase. 4. During the placebo phase, MAP (-3 +/- 1 mm Hg), TPR (-10 +/- 4%) and FVR (-9 +/- 4%) were lower after exercise as compared with the control rest period. 5. During ACE inhibition, MAP (-3 +/- 1 mm Hg) and TPR (-8 +/- 4%) were lower, but FVR (+32 +/- 15%) was increased after exercise as compared with the control rest period. 6. Thus, blood pressure and TPR decreased similarly after exercise during the placebo phase and during ACE inhibition. However, differences in post-exercise forearm haemodynamics during the placebo phase and during ACE inhibition indicate that underlying regional haemodynamics are modified.

Adult↗

Abdominal and femoral adipose tissue lipolysis and cardiovascular disease risk factors in men.

The relationships between subcutaneous abdominal and femoral fat cell lipolyses, plasma free-fatty acid (FFA) levels and metabolic variables considered as risk factors for cardiovascular disease (CVD) (plasma glucose, insulin and lipoprotein levels) were investigated in 54 men, aged 36 +/- 3 (SD) years, covering a wide range of body fatness values (body mass indices from 19 to 34 kg m-2). Although there were no consistent relationships between femoral fat cell weight and the metabolic profile, positive and significant associations were found between abdominal fat cell weight and most of the metabolic indices. However, abdominal fat cell lipolysis measured with an alpha 2-(clonidine) or a beta-agonist (isoproterenol) was unrelated to metabolic variables. In contrast, femoral fat cell lipolysis measured in the presence of clonidine was positively associated with fasting plasma insulin, cholesterol (CHOL) and apolipoprotein (apo) B levels, as well as with LDL-CHOL and LDL-apo B concentrations. No association was found between isoproterenol-stimulated lipolysis of femoral adipocytes and the metabolic profile. Comparison of two subgroups of men with either low or high femoral residual lipolysis with clonidine revealed that subjects with the lowest femoral alpha 2-adrenergic component (i.e. the highest residual lipolysis) displayed significant alterations in both plasma lipid-lipoprotein and glucose-insulin levels which could be predictive of an increased risk of CVD. Free fatty acid (FFA) levels measured in the fasting state and during an oral glucose tolerance test (OGTT) were positively associated with fasting plasma insulin and triglyceride levels as well as with both glucose and insulin areas measured during the OGTT. However, regional adipose tissue lipolysis measured in vitro was unrelated to plasma FFA levels. These results support the view that both femoral adipose tissue lipolysis and plasma FFA levels are significant correlates of plasma glucose-insulin homeostasis and lipoprotein-lipid levels, in men. However, as adipose tissue lipolysis and plasma FFA are unrelated to each other, they may be associated with risk variables through independent mechanisms.

Abdomen↗

Components of postprandial thermogenesis in relation to meal frequency in humans.

Experiments on dogs have shown that the size of the meal has no effect on the early cephalic postprandial thermogenesis, and that four small meals are more thermogenic than a larger meal with the same total caloric content as the four meals. A study was repeated on human subjects who were fed during alternating weeks either one large meal (653 kcal (1 kcal = 4.1855 kJ)) or four small meals (163 kcal) at 40-min intervals. Oxygen consumption and respiratory exchange ratio determinations indicated (i) larger overall increase in postprandial thermogenesis with the four meals than with one meal and (ii) an enhancement of glucose utilization with the large meal compared with greater lipid utilization with the four meals. On the basis of indirect evidence from previous investigations it is suggested that the enhanced thermogenesis observed in the four-meal experiment is due to lipid mobilization caused by repeated stimulation of the sympathetic nervous system with palatable food. Blood analysis indicated a reduced elevation of plasma glucose in the four-meal experiment. The variations of insulin and C-peptide exactly paralleled those observed for glucose. It is concluded that the increased frequency of feeding significantly reduces insulin secretion in subjects fed a relatively high carbohydrate meal. In addition to this beneficial effect, increasing the number of meals increased thermogenesis and fat utilization.

Adult↗

Effect of adrenal demedullation and (or) physical training on glucose tolerance in the rat.

Physical training increases insulin sensitivity by mechanisms not yet fully understood. Because exercise also modulates adrenergic system activity, the present study was designed to ascertain whether the improved glucose homeostasis observed in trained rats is influenced by epinephrine secretion from the adrenal medullae. Male Wistar rats previously submitted to adrenal demedullation or sham operated were kept sedentary or trained on a treadmill over a 10-week period. An intravenous glucose tolerance test (IVGTT) was done 64 h after the last bout of exercise. Basal plasma glucose levels were reduced by physical training (p < 0.005) and by adrenal demedullation (p < 0.001). Adrenodemedullated rats had lower (p < 0.005) plasma glucose levels than sham-operated animals over the whole glucose tolerance curve. Trained animals had lower (p < 0.01) plasma glucose levels than sedentary rats throughout the IVGTT, except at 45 min. The glucose disappearance rate measured after the glucose bolus injection was increased by training (p < 0.05), whereas it was not modified by adrenal demedullation. Basal plasma insulin levels were reduced (p < 0.001) by physical training but unaffected by adrenal demedullation. During the IVGTT, adrenodemedullated rats had higher (p < 0.01) plasma insulin levels at 2, 4, and 6 min, whereas trained animals had lower (p < 0.05) plasma insulin levels throughout the test. Moreover, insulin in adrenodemedullated and trained rats had returned to basal levels at 30 min. The area under the curve for insulin was diminished by physical training (p < 0.001) but was not modified by adrenal demedullation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Medulla↗

Effect of endurance training on beta-adrenergic system in three different skeletal muscles.

The beta-adrenergic receptor density (Bmax) and adenylate cyclase (AC) activity in the soleus muscle and deep red and white superficial portions of the vastus lateralis muscle were evaluated in a group of rats submitted to a progressive 10-wk treadmill running program (n = 19) and compared with a group of rats kept sedentary (n = 17) during the same period of time.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenylyl Cyclases↗

Physical training attenuates phosphocreatine and long-chain acyl-CoA alterations in diabetic rat heart.

This study was designed to assess the effect of physical training on high-energy phosphate levels in the heart of diabetic rats. Diabetes was induced with streptozocin (50 mg/kg), and exercise training was carried out on a treadmill with a progressive 10-wk program. Plasma glucose levels at the end of the training program showed only a small improvement of the diabetic state in trained animals (21.7 +/- 1.3 vs. 24.4 +/- 0.8 mmol/l; P < 0.05). The lower heart rate observed in sedentary diabetic rats (279 +/- 6 vs. 356 +/- 5 beats/min; P < 0.001) was improved by physical training (301 +/- 8 beats/min; P < 0.05 vs. sedentary diabetics). Significantly lower phosphocreatine levels were found in sedentary diabetic rats (12.0 +/- 0.7 mumol/g dry wt) than in sedentary control rats (15.0 +/- 0.9 mumol/g dry wt; P < 0.05) but not in trained diabetic rats (13.7 +/- 0.7 mumol/g dry wt). ATP levels were not affected by diabetes but were increased by training. The increased long-chain acyl-CoA levels in sedentary diabetic rats (146 +/- 7 vs. 119 +/- 8 mumol/g dry wt in sedentary control rats; P < 0.05) were improved by training (138 +/- 6 mumol/g dry wt; P > 0.05 vs. sedentary control rats). These data indicate that the diminution in phosphocreatine levels observed in the heart tissue of chronically diabetic rats can be attenuated by an exercise training program.

Acyl Coenzyme A↗

Metabolic heterogeneity associated with high plasma triglyceride or low HDL cholesterol levels in men.

To further understand the factors involved in the regulation of high plasma triglyceride (TG) or low plasma high density lipoprotein cholesterol (HDL-C) levels, three groups of male subjects (normal TG with low HDL-C levels, high TG with normal HDL-C levels, and high TG with low HDL-C levels) were compared with a sample of normolipemic men with normal TG and HDL-C plasma levels. Mean age was 34 years (range, 20-42 years), and none of the subjects had plasma TG levels > 4.0 mmol/l or familial hypercholesterolemia. Both groups of subjects with high TG levels had a higher body mass index, waist circumference, waist-to-hip circumferences ratio, and a higher ratio of abdominal to femoral adipose tissue areas as measured by computed tomography when compared with normolipemic control subjects. However, during an oral glucose tolerance test only high TG-low HDL-C men had fasting hyperinsulinemia and higher plasma insulin levels compared with normolipemic subjects. In addition, the high TG-low HDL-C group showed reduced HDL apoprotein (apo) A-I levels and a low HDL2-C/HDL3-C ratio. These changes were observed along with a nonsignificant trend for a lower plasma postheparin lipoprotein lipase activity. However, among subjects with high TG and normal HDL-C levels, no evidence of insulin resistance or of a reduction in postheparin lipoprotein lipase activity was observed, suggesting that the high plasma TG levels could be attributed to an increased production of apo B-containing lipoproteins, as high plasma apo B and low density lipoprotein (LDL)-apo B levels were observed in this group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Captopril or conventional therapy in hypertensive type II diabetics. Three-year analysis.

The effects of long-term treatment with captopril and conventional therapy on albuminuria and metabolic parameters were compared in 74 hypertensive type II diabetics with normal serum creatinine. Patients were treated double-blind with either captopril monotherapy or combined with hydrochlorothiazide or therapy with metoprolol, hydrochlorothiazide, or both for 36 months. The treatment was titrated to achieve goal diastolic blood pressure of < or = 85 mm Hg. The reductions in blood pressures during treatment were similar in patients with (n = 21) and without (n = 53) microalbuminuria treated with either captopril or conventional therapy. No significant changes in albuminuria occurred in normoalbuminuric patients with either therapy. Although albuminuria fell in nearly all patients with microalbuminuria treated with captopril, it rose in eight of 12 patients on conventional therapy, with macroalbuminuria developing in two of them. Renal function was preserved by both types of treatment in both patient groups. Long-term treatment with either conventional therapy or captopril did not alter metabolic variables. We conclude that captopril alone or in combination decreases albuminuria and prevents the development of macroalbuminuria in hypertensive type II diabetics with persistent microalbuminuria. The renoprotective effect of this agent, however, remains to be demonstrated with longer term data on renal function. Aggressive antihypertensive treatment with either captopril or conventional therapy appears to be effective in preventing the onset of microalbuminuria in most normoalbuminuric patients. In contrast, with previous short-term studies, the use of converting enzyme inhibitors or conventional therapy did not cause adverse metabolic effects.

Aged↗

Apolipoprotein E polymorphism modifies relation of hyperinsulinemia to hypertriglyceridemia.

The effect of apolipoprotein E polymorphism on the established relationships between glucose tolerance, plasma insulin levels, and plasma lipoprotein concentrations were investigated in a sample of women defined on the basis of apolipoprotein E phenotypes. In women with the apolipoprotein E epsilon 2 allele (n = 22), fasting plasma insulin and glucose and insulin areas under the curve measured during an oral glucose tolerance test were positively correlated with plasma triglyceride levels (0.48 < or = r < or = 0.70; P < 0.05). In this group, very-low-density lipoprotein cholesterol and very-low-density lipoprotein triglyceride concentrations were positively correlated with fasting insulin levels, the insulin area, and with the ratio of insulin area to glucose area. In women (n = 24) homozygous for the apolipoprotein E epsilon 3 allele (the most common allele), essentially similar associations were found. In contrast, in women (n = 17) with the apolipoprotein E epsilon 4 allele, no association was found between glucose tolerance, fasting and postglucose plasma insulin levels, and plasma lipid and lipoprotein levels. These results suggest that apolipoprotein E polymorphism substantially modifies the associations between glucose tolerance, plasma insulin levels, and plasma lipoprotein concentrations. Additional analysis of the data revealed that apolipoprotein E polymorphism did not alter the relationships between body fat distribution and fasting insulin and postglucose insulin levels, but no correlation was observed between fatness indexes and glucose tolerance among apolipoprotein E epsilon 2 carriers.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗

Physical training reverses defect in mitochondrial energy production in heart of chronically diabetic rats.

This study examined the impact of physical training on cardiac mitochondrial respiration of rats with chronic diabetes mellitus. Diabetes was induced by an intravenous injection of STZ (50 mg/kg) and only rats with a blood glucose level between 14 and 22 mM 1 wk later were kept in the protocol. Exercise training was conducted on a treadmill with a progressive 10-wk program. Animals were killed at the end of the training program, and mitochondria were isolated from ventricular tissue by differential centrifugation. Both state 3 respiration and oxidative phosphorylation rates were depressed significantly in the mitochondria of diabetic rats. These alterations were reversed completely to normal by physical training, without any significant changes in plasma glucose or insulin levels. The activity of ANT was not affected by diabetes or training. These results indicate that the depressed OPR present in isolated heart mitochondria from chronically diabetic rats is reversed to normal by physical training, apparently by mechanisms independent of blood glucose control. This correction in mitochondrial energy production may explain the improvement in cardiac function previously reported in trained diabetic rats.

Analysis of Variance↗

Evidence for a role of insulin in the regulation of abdominal adipose tissue lipoprotein lipase response to exercise training in obese women.

Abdominal and femoral adipose tissue lipoprotein lipase (AT-LPL) activities were measured in ten obese premenopausal women (mean age 35 +/- 5 years) who took part in a six month endurance exercise training programme. The programme involved four to five 90 min training sessions per week at about 50 to 55% of maximal endurance power (VO2max). Before training, the ratio of insulin to glucose area measured during an oral glucose tolerance test (OGTT) was significantly correlated with fat mass (r = 0.72, P < 0.05) as well as with abdominal AT-LPL activity (r = 0.69, P < 0.05). The training programme induced a significant increase in VO2max (P < 0.05) whereas no significant change in the mean body composition was observed. Abdominal as well as femoral AT-LPL activities were significantly reduced after the exercise training programme (P < 0.05) whereas plasma post-heparin (PH) LPL activity was significantly increased by training (P < 0.05). No significant association was observed between changes in VO2max and in body composition parameters and changes in abdominal or femoral AT-LPL activities. However, changes in insulin sensitivity, as estimated by changes in the insulin area/glucose area ratio were positively correlated with changes in abdominal AT-LPL activity expressed on a per cell (r = 0.72, P < 0.05) or per surface area (r = 0.81, P < 0.01) basis. These results suggest that the reduction in AT-LPL activity in both fat depots following endurance training in obese women can occur despite the lack of significant decrease in body weight and average fat cell size.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdomen↗

Genetic aspects of susceptibility to obesity and related dyslipidemias.

Obesity has a multifactorial origin. However, although environmental variables undoubtedly play a role in the development of obesity, it is now clear that genetic variation is also involved in the determination of an individual's susceptibility to body fat accumulation. In addition, it is also widely accepted that obesity is not a single homogeneous phenotype. It is also heterogeneous regarding its causes and metabolic complications. The regional distribution of body fat appears to be an important correlate of the metabolic complications that have been related to obesity. Due to their higher accumulation of abdominal fat, men are generally more at risk for the metabolic complications of obesity than women whereas some obese women, with large gluteal-femoral adipose depots may have a cosmetic problem which may not necessarily require medical intervention. Several studies have been conducted to understand the mechanisms by which abdominal obesity is related to diabetes, hypertension and cardiovascular disease. It appears that the increased risk of abdominal obesity is the result of complex hormonal and metabolic interactions. Studies in genetic epidemiology have shown that both total body fatness and the regional distribution of body fat have a significant genetic component. Standardized intervention studies using an identical twin design have shown that individuals that have the same genetic background tend to show similar changes in body fat and in plasma lipoprotein levels when exposed to standardized caloric excess or energy restriction. Finally, although abdominal obesity is a significant risk factor for cardiovascular disease, not every abdominal obese subject will experience metabolic complications, suggesting that some obese individuals may be more susceptible than others. Variation in several genes relevant to lipid and lipoprotein metabolism may alter the relation of abdominal obesity to dyslipoproteinemias. Abdominal obesity should therefore be considered as a factor that exacerbates an individual's susceptibility to cardiovascular disease.

Adipose Tissue↗

Heterogeneous glycaemic and insulinaemic responses to oral glucose in non-diabetic men: interactions between duration of obesity, body fat distribution and family history of diabetes mellitus.

The interaction between environmental and genetic factors in the alterations of glucose-insulin homeostasis was studied in 104 non-diabetic men. Family history of diabetes mellitus was used as an index of genetic predisposition to diabetes. Body composition was measured by underwater weighing whereas subcutaneous and visceral adipose tissue areas were measured at the abdominal and femoral levels by computed tomography. The sample was first divided into two groups. The first group included subjects with "normal" glycaemic and insulinaemic responses during a 75 g oral glucose tolerance test. The second group was composed of subjects either with a high glucose response or high insulin response or both. Men included in the second group were different from the "normal" subjects for almost all body fatness variables. They also presented a prevalence of a positive family history of diabetes which was significantly higher than "normal" subjects. The second group was then divided into three distinct subgroups based on insulin and glucose responses of the subjects during the oral glucose tolerance test. Subjects with high insulin but "normal" glucose responses were characterized by significantly higher levels of total body fat and deep abdominal adipose tissue when compared to the "normal" group (p less than 0.05). Men with both high insulinaemic and glycaemic responses displayed higher body fatness values and higher deep and subcutaneous abdominal adipose tissue areas (p less than 0.05) in comparison with "normal" subjects. They also had a higher body mass index at age 20 years than control subjects and subjects with high insulin but "normal" glucose responses.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗

Is body fat loss a determinant factor in the improvement of carbohydrate and lipid metabolism following aerobic exercise training in obese women?

Thirty-one obese, premenopausal women aged 35.4 +/- 5.1 (SD) years exercised for 90 minutes at approximately 55% of maximal aerobic power (VO2max) four to five times a week for a period of 6 months. The training program induced a significant increase in VO2max (P < .001) and significant improvements in carbohydrate and lipid metabolism, as reflected by decreased plasma insulin (INS) concentrations measured in the fasting state and after glucose (GLU) ingestion (INS area, P < .001), by reduced plasma cholesterol (C) and low-density lipoprotein cholesterol (LDL-C) levels (P < .001), and by increased ratios of high-density lipoprotein cholesterol (HDL-C)/LDL-C and HDL2-C/HDL3-C (P < .05 and P < .001, respectively). Changes in body fat mass were positively associated with changes in the INS area/GLU area ratio (r = .49, P < .05) and with changes in very-low-density lipoprotein triglycerides ([VLDL-TG] r = .49, P < .05). Furthermore, changes in the INS area were positively associated with changes in VLDL-TG (r = .51, P < .05). Although no significant mean change in body composition was observed, important individual variation was noted. Twenty women showed a reduction in body fat mass (mean reduction, 2.63 +/- 2.2 kg), whereas 11 women showed an increase in adipose mass (mean increase, 2.79 +/- 2.36 kg). Comparable increases in VO2max were observed between the two groups. The group that showed a decrease in body fat mass with exercise also had significant improvements in carbohydrate and lipid metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Adrenodemedullation does not impair the beneficial effect of physical training in streptozotocin-diabetic rats.

This study was designed to ascertain if the improvement in glucose homeostasis found in diabetic animals submitted to physical training is due to an increased secretion of epinephrine by the adrenal medullae. Male Wistar rats were surgically adrenodemedullated (ADM group) or sham-operated (SHAM group). After a 3-week recovery period, a bolus of streptozotocin (40 mg/kg) was injected intravenously (IV), and the animals presenting 1 week later with a blood glucose value between 14 and 22 mmol/L were retained in the protocol and randomly assigned to a sedentary (SHAM-DS and ADM-DS) or trained (SHAM-DT and ADM-DT) group. Physical training was done on a treadmill according to a 10-week progressive program. An IV glucose tolerance test (0.5 g/kg) was performed in previously cannulated rats, 64 hours after the last bout of exercise. Pancreatic insulin and glucagon content was also determined. In sedentary diabetic rats, adrenodemedullation had no effect on plasma glucose, insulin, or glucagon levels, neither in the basal state nor following the glucose load. Basal glucose levels were diminished by training in both SHAM (16.1 +/- 1.5 v 21.8 +/- 0.4 mmol/L; P less than .01) and ADM (12.4 +/- 1.7 v 21.1 +/- 1.2 mmol/L; P less than .01) groups, with values lower in ADM-DT than in SHAM-DT rats (P less than .05). After glucose loading, the glucose levels were significantly lower (P less than .01) throughout the test in both SHAM-DT and ADM-DT rats than in their sedentary counterparts.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Medulla↗

Physical training increases beta-adrenoceptor density and adenylate cyclase activity in high-oxidative skeletal muscle of diabetic rats.

The effects of physical training on beta-adrenergic-receptor density (Bmax) and adenylate cyclase (AC) activity in soleus muscles (type I) and the deep red portion (type IIa) and superficial white portion (type IIb) of vastus lateralis muscles in diabetic rats were investigated. Rats were rendered diabetic with streptozotocin ([STZ] 45 mg/kg intravenously [IV]) and were either kept sedentary ([SD] n = 12) or submitted to a progressive 10-week treadmill running program ([TD] n = 13). A group of normal sedentary rats served as controls ([SC] n = 13). Plasma glucose levels were increased in SD rats in comparison with SC rats (21.3 +/- 1.4 mmol/L v 7.7 +/- 0.2; mean +/- SE, P < .001), but levels were partially reversed to normal by training (10.7 +/- 1.7; P < .01 v SD). The gastrocnemius nicotinamide adenine dinucleotide (NAD)-isocitrate dehydrogenase (ICDH) activity was significantly increased in TD rats in comparison to SC or SD rats (P < .001). The Bmax and antagonist affinity (Kd) determined with 125iodocyanopindolol (ICYP) were not affected by diabetes in any of the three types of muscle. In type I muscle, TD rats showed a significant 67% increase in Bmax compared with that of SD rats (TD 26.7 +/- 2.0 v SD 16.0 +/- 1.0; P < .001). In type IIa muscle, Bmax was significantly higher by 68% in TD rats as compared with SD rats (TD 16.5 +/- 1.7 v SD 9.8 +/- 0.9 fmol/mg protein; P < .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenylyl Cyclases↗

Partial correction of impaired creatine kinase activity in diabetic rat heart by physical training.

The effect of physical training on total creatine kinase (CK), CK-MM, and CK-MB isoenzyme activity was studied in hearts of diabetic and control rats. Diabetes was induced with streptozotocin (50 mg/kg), and only rats with blood glucose levels between 14 and 22 mmol/L 1 week later were kept in the protocol. Exercise training was performed on a treadmill in a progressive 10-week program. Physical training did not induce any significant changes in plasma glucose or insulin levels in diabetic rats. Total CK, CK-MM, and CK-MB activity was decreased in diabetic rat heart by 27%, 22%, and 56%, respectively. Physical training did not induce any important changes in CK activity in heart of nondiabetic rats. However, in diabetic rat heart, training increased total CK activity by 13%, CK-MM activity by 12%, and CK-MB activity by 31%. We conclude that the decrease in cardiac CK activity observed in chronic experimental diabetes mellitus can be partly alleviated by a program of physical training. This may be one of the mechanisms whereby physical conditioning improves cardiac function in experimental diabetes.

Analysis of Variance↗