Administration of slow-release nifedipine does not affect lactate threshold,hormone release during exercise,and quality of life in normal subjects

Summary In a double-blind crossover study of 10 normal healthy subjects, we examined the effects of slow-release nifedipine (nifedipine-SR, 10 mg b.i.d) administration on exercise capacity, hormone levels during exercise, and quality of life (QOL) after a 2-week treatment. Two exercise tests, a progressive exercise test and a constant work-rate exercise test, were performed. Maximal oxygen uptake (\.VO₂max) and blood lactate concentration were measured during the progressive exercise test and the exercise intensity corresponding to half lactate threshold (LT), LT, and 4 mmol/l of lactate concentration was determined. Subjects underwent 20 minutes of constant work-rate exercise at each work load, and blood lactate, plasma epinephrine, plasma norepinephrine, plasma renin activity, plasma aldosterone, atrial natriuretic peptide, plasma β-endorphin, and met-enkephalin were measured. Taking nifedipine-SR had no effect on the responses of blood pressure, heart rate, VO₂max, maximal work load, and LT compared to taking placebo. Blood lactate, plasma catecholamine, plasma renin activity, aldosterone, atrial natriuretic peptide, and β-endorphin levels increased during exercise, and there was no difference between nifedipine-SR and placebo. Met-enkephalin did not increase with either treatment. In the QOL questionnaires, no differences were noted between the two treatments. These findings suggest nifedipine-SR to be a potentially useful drug in view of the lack of effect on exercise capacity, hormone release, and QOL.     

Acute effects of alpha- and beta-adrenoceptor blockade on plasma atrial natriuretic peptides during exercise in elderly patients with mild hypertension.

In a randomized study in 26 elderly patients with mild essential hypertension, acute effects of alpha- and beta-adrenoceptor blockade on plasma ANP levels were examined at rest and during ergometric exercise. Plasma ANP level and LVEF were measured before and after administration of prazosin (an alpha 1-adrenergic blocker), atenolol (a cardioselective beta-adrenergic blocker), or carteolol (a nonselective beta-adrenergic blocker). Plasma ANP level was increased by exercise. Carteolol and atenolol increased plasma ANP levels at rest and during exercise, but the effect of atenolol was not statistically significant. Prazosin significantly suppressed the ANP values at rest and during exercise. The LVEF was increased by prazosin and decreased by beta-blockers, especially by carteolol. Multivariate regression analysis showed that LVEF was the most significant predictor of the plasma ANP level at maximal exercise; the resting blood pressure and heart rate were not predictors of this value. The results showed that single administrations of an alpha-blocker and a nonselective beta-blocker had opposite effects on the plasma ANP level both at rest and during exercise in elderly patients with mild essential hypertension. The observed difference in the ANP response seems to be related to changes in left ventricular function rather than changes in blood pressure or heart rate.     

Atrial Natriuretic Peptide during Exercise in Patients with Coronary Heart Disease before and after Single Dose Atenolol and Acebutolol

Plasma atrial natriuretic peptide (ANP) was measured during dynamic exercise in 10 patients with coronary heart disease before and after single dose atenolol 50 mg and acebutolol 200 mg, respectively. Systolic blood pressure, heart rate and the rate-pressure product increased during exercise before and after β-blockade, but levels were lower after β-blockade. Plasma ANP levels at rest were unchanged after atenolol, but rose after acebutolol (p<0.01). During exercise plasma ANP increased significantly both before and after β-blockade, but plasma ANP levels were higher after acebutolol at all workloads (p<0.05), whereas plasma ANP levels after atenolol were higher at 125 W exclusively (p<0.05). The augmented ANP levels during exercise after β-blockade probably reflect catecholamine-stimulated ANP release, whereas the elevated plasma ANP levels after acebutolol at rest might be a β-adrenoceptor-mediated ANP release due to the intrinsic sympathomimetic effect of acebutolol.     

Value of cardiopulmonary exercise testing and big endothelin plasma levels to predict short-term prognosis of patients with chronic heart failure

Objectives. We tested the hypothesis that, in patients with stable heart failure, measuring big endothelin-1 (ET-1) plasma level at rest predicts short-term prognosis better than peak oxygen consumption (Vo₂max) at exercise.Background. Cardiopulmonary exercise testing and evaluation of neurohumoral plasma factors are established tools to estimate survival in patients with heart failure. No data, however, exist comparing the prognostic value of both marker categories simultaneously.Methods. Two hundred twenty-six heart failure patients were studied in regard to a combined end point of death and prioritization for urgent cardiac transplantation within 1 year follow-up.Results. During the study period 149 patients were without cardiac events (group A), 69 patients died or were urgently transplanted (group B) and 8 patients were alive after a nonurgent heart transplant operation. Norepinephrine (p < 0.0001), atrial natriuretic peptide (p < 0.001), big endothelin plasma levels (p < 0.0001 as well as workload, Vo₂max and achieved percentage of predicted peak oxygen consumption (pVo₂max) (all p < 0.0001) differed significantly between groups A and B. In multivariate stepwise regression analysis, however, only big ET-1 plasma concentration (×2 = 74.4, p < 0.0001), New York Heart Association function class (×2 = 33.9, p < 0.0001), maximal workload (×2 = 7.2, p < 0.01, and plasma atrial natriuretic peptide (ANP) concentration (×2 = 4.6, p < 0.05) were independently related to outcome. Peak oxygen consumption or pVo₂max did not reach statistical significance in this model. Event-free survival rates were significantly lower in patients with a big ET-1 level of 4.3 fmol/ml or more than with lower big ET-1 levels (p < 0.0001).Conclusion. We conclude that in patients with chronic heart failure who are stable on oral therapy measuring big ET-1 and ANP plasma levels may be a valuable noninvasive adjunct to improve the prognostic accuracy of detecting high risk patients compared with exercise testing alone.     

Influence of exercise on plasma atrial natriuretic factor levels in patients with myocardial infarction

The influence of dynamic exercise on plasma atrial natriuretic factor (ANF) levels was studied in a group of 10 patients with myocardial infarction (MI) and five patients with atypical chest pain (control group). Exercise protocol consisted of three fixed workloads (25, 50, and 75 watts) every 4 minutes with the use of a supine bicycle ergometer. Plasma ANF levels and hemodynamic indices were measured before, during, and 10 minutes after exercise. In the MI group, plasma ANF levels significantly increased at the 75-watt workload and significantly decreased at 10 minutes after exercise, whereas in the control group, the increase in plasma ANP levels after a 75-watt workload, compared with those at rest, was not significant. Significant correlations of pulmonary artery wedge pressure, right atrial pressure, mean arterial pressure, and heart rate to plasma ANF levels were observed at four points obtained before and during each stage of exercise in the MI group. Furthermore, a significant correlation between maximal creatine kinase levels and plasma ANF levels at a 75-watt workload and a significant inverse correlation between left ventricular ejection fraction and plasma ANF levels at a 75-watt workload were observed. These results suggest that the increase in the circulating ANF level during exercise in MI is associated with elevated atrial pressure resulting from left ventricular dysfunction and that measurement of ANF during exercise may be an indication of the severity of MI and associated left ventricular dysfunction.     

Isosorbide dinitrate and cardiovascular adaptation to exercise.

Sixteen men with well-documented angina pectoris and without previous myocardial infarction performed a multistage exercise stress test to determine their levels of exercise-induced limitations, characterized by onset of chest discomfort or electrocardiographic ischemic changes, or both. Following a control study, each subject was assigned randomly to either a placebo- or vasodilator-treated group, received chewable medication, and was retested 30 minutes after chewing the medication. Blood pressure, heart rate, and electrocardiographic changes were measured during rest, peak exercise, and recovery. A phonocardiogram, carotid-pulse contour, and single-lead electrocardiogram were recorded simultaneously at supine rest before and immediately after exercise, and systolic time intervals were measured. Results indicated that chewable isosorbide dinitrate reduced systolic blood pressure and the triple product (systolic blood pressure X heart rate X ejection time) significantly during rest and reduced the left ventricular ejection time corrected for heart rate both at rest and peak exercise; no significant differences were observed in the placebo group. The ability to achieve an increased workload was observed in both groups, and the threshold for ischemic manifestations occurred at comparable triple-product levels in both during pretreatment and posttreatment studies.     

Cardiovascular response to exercise in diabetic patients: influence of autonomic neuropathy of different severity

Summary We investigated cardiovascular function and plasma catecholamine response during incremental exercise and recovery in diabetic patients with (DAN+) and without autonomic neuropathy (DAN–). The former group was divided according to the presence of parasympathetic (DAN+PH–) or associated parasympathetic and sympathetic (DAN+PH+) damage to the autonomic nervous system. A group of healthy volunteers was studied as a control group. All the patients and control subjects underwent a submaximal or symptom-limited incremental exercise test using a cycle-ergometer. Air flow and respiratory gas fractions were sampled at the level of the mouth allowing a breath-by-breath analysis of oxygen consumption (VO₂). Heart rate and systolic blood pressure were recorded and venous blood samples were obtained from the patients at rest and during each minute of exercise and recovery to measure norepinephrine and epinephrine plasma levels. Haemodynamic parameters and plasma catecholamines were computed at rest and at 25, 50, 75 and 100% of the peak VO₂ (VO_{2 max}). The breath-by-breath relationships among VO₂, heart rate and VO₂/heart rate against work were assessed during exercise for patients and control subjects. While VO_{2 max} in absolute values was not significantly different among the diabetic groups, VO_{2 max} was much less in diabetic patients than in control subjects (p<0.01). During exercise the rate of heart rate, systolic blood pressure, norepinephrine and epinephrine increase was different among the diabetic groups, being significantly blunted in DAN+PH+. The VO₂/work relationship of the three diabetic groups was similar but markedly reduced in respect to that of control subjects (p<0.001). The relationship between oxygen pulse (VO₂/heart rate) and work showed no differences among the diabetic groups, whereas its slope was significantly steeper in control subjects (p<0.01 vs DAN–; p<0.05 vs DAN+PH– and DAN+PH+). In conclusion during incremental exercise both DAN+PH– and DAN+PH+ exhibit abnormal heart rate, systolic blood pressure and catecholamine responses which, however, appear clearly distinct between the two groups of DAN+. In DAN+ the VO₂ increment is reduced during exercise. Since DAN–show the same impairment, this particular finding seems most likely to be influenced by factors (i.e.: diabetic cardiomyopathy) other than overt autonomic neuropathy.Abbreviations C Control subjects - DAN– diabetic patients without autonomic neuropathy - DAN+ diabetic patients with autonomic neuropathy - DAN+PH– diabetic patients with autonomic neuropathy without postural hypotension - DAN+PH+ diabetic patients with autonomic neuropathy with postural hypotension - V_E minute ventilation - VO₂ oxygen consumption - VCO₂ carbon dioxide production - AT anaerobic threshold - SaO₂ arterial oxygen saturation - HR heart rate - SBP systolic blood pressure - CW cardiac work - VO_{2 max} peak VO₂     

Integrated effects of the vasodilating beta-blocker nebivolol on exercise performance, energy metabolism, cardiovascular and neurohormonal parameters in physically active patients with arterial hypertension

OBJECTIVE: The present study was designed to investigate the integrated effects of the beta-1-selective blocker with vasodilator properties, nebivolol, on systemic haemodynamics, neurohormones and energy metabolism as well as oxygen uptake and exercise performance in physically active patients with moderate essential hypertension (EH). DESIGN AND METHODS: Eighteen physically active patients with moderate EH were included: age: 46.9 +/- 2.38 years, weight: 83.9 +/- 2.81 kg, blood pressure (BP): 155.8 +/- 3.90/102.5 +/- 1.86 mm Hg, heart rate: 73.6 +/- 2.98 min(-1). After a 14-day wash-out period a bicycle spiroergometry until exhaustion (WHO) was performed followed by a 45-min submaximal exercise test on the 2.5 mmol/l lactate-level 48 h later. Before, during and directly after exercise testing blood samples were taken. An identical protocol was repeated after a 6-week treatment period with 5 mg nebivolol/day. RESULTS: Nebivolol treatment resulted in a significant (P < 0.01) decrease in systolic and diastolic BP and heart rate at rest and during maximal and submaximal exercise. Maximal physical work performance, blood lactate and rel. oxygen uptake (rel. VO(2)) before and after nebivolol treatment at rest and during maximal and submaximal exercise remained unaltered. Free fatty acid, free glycerol, plasma catecholamines, beta-endorphines and atrial natriuretic peptide (ANP) increased before and after treatment during maximal and submaximal exercise but remained unaltered by nebivolol treatment. In contrast, plasma ANP levels at rest were significantly higher in the presence of nebivolol, endothelin-1 levels were unchanged. CONCLUSIONS: Nebivolol was effective in the control of BP at rest and during exercise in patients with EH. Furthermore, nebivolol did not negatively affect lipid and carbohydrate metabolism and substrate flow. The explanation for the effects on ANP at rest remain elusive. This pharmacodynamic profile of nebivolol is potentially suitable in physically active patients with EH.     

Plasma concentrations of atrial natriuretic peptide during physical exercise in patients with congestive heart failure

Summary Plasma concentrations of atrial natriuretic peptide (ANP) were measured in 25 patients with organic heart disease during physical exercise (baseline and maximum workload) in order to investigate if the responsiveness of stimulated release of ANP is still preserved in patients with heart failure and chronically elevated cardiac filling pressures. Since plasma concentrations of ANP are known to be positively correlated with mean right atrial pressures (RAP), the patients were divided into two groups according to their resting RAP: group I: those with normal RAP ( 5 mmHg; n=11); group II: those with elevated RAP (>5 mmHg; n=14). Under baseline conditions RAP (3.2±0.4 mmHg vs. 8.8±0.7 mmHg; p<0.01), pulmonary artery diastolic pressure (PADP; 9.5±0.9 mmHg vs. 17.9±1.8 pg/ml; p.<0.01), and plasma ANP levels (128±19 pg/ml vs. 204±60 pg/ml; p<0.06) were significantly lower in group I than in group II. Both at rest and during maximum workload, plasma ANP concentrations were closely related to RAP, PADP, and mean pulmonary artery pressures in both groups.During exercise in all patients, RAP and PADP significantly increased, as well as plasma ANP concentrations. Similar increments in plasma ANP concentrations were accompanied by greater changes in RAP in group II than in group I. However, identical changes in PADP lead to identical increments in plasma ANP concentrations in both groups.In conclusion, the increments of plasma ANP concentrations during physical exercise were independent of the resting values of PADP, RAP, and plasma ANP concentrations. During exercise the increments in plasma ANP concentrations for identical changes of PADP were not significantly influenced by the resting conditions; only in patients with elevated RAP at rest did increments in RAP during exercise induce a slightly reduced ANP release compared with patients who had normal right ventricular filling pressures. These data indicate that the responsiveness of ANP release during physical exercise is only slightly impaired in patients with heart failure and chronically elevated cardiac filling pressures.Dedicated to Professor Dr. F. Loogen on the occasion of his 70th birthday.     

Efficacy of epanolol versus metoprolol in angina pectoris: report from a Swedish multicentre study of exercise tolerance.

The efficacy of epanolol vs. metoprolol in stable angina pectoris was compared in 114 patients recruited to a randomized double-blind cross-over study, consisting of a 4-week period on each drug. Epanolol (200 mg) or metoprolol (200 mg) was administered daily. Bicycle ergometry was performed at the end of each treatment period. The maximum workload was 134 +/- 18 W on epanolol and 133 +/- 37 W on metoprolol (NS). Values for resting heart rate (epanolol, 72 +/- 11 beats min-1; metoprolol, 64 +/- 12 beats min-1; P less than 0.001), systolic blood pressure (epanolol, 143 +/- 21 mmHg; metoprolol, 137 +/- 21 mmHg; P less than 0.05) and diastolic blood pressure (epanolol, 88 +/- 10 mmHg; metoprolol, 84 +/- 11 mmHg; P less than 0.01) were all higher on epanolol treatment. During exercise, the increase in heart rate and blood pressure was of similar magnitude during the two treatment periods, and these parameters did not differ significantly at the last identical workload. The rating of chest pain, fatigue and dyspnoea did not differ between the two drugs during submaximal or maximal exercise. In conclusion, 200 mg of epanolol and metoprolol have similar efficacy with regard to exercise tolerance. As expected from the partial agonist activity present in epanolol but not in metoprolol, the former drug resulted in a higher heart rate and blood pressure at rest. The observed increase in these parameters during exercise was similar for both drugs.     

Comparative analysis of physiologic responses to three different maximal graded exercise test protocols in healthy women

The purpose of this study was to compare the three most commonly used maximal graded exercise test (GXT) protocols in healthy women. Submaximal and maximal metabolic and hemodynamic responses were determined from two treadmill protocols, Bruce and Balke, and a bicycle protocol, in 49 women. Maximum oxygen uptake (VO₂ max) was significantly different among protocols (Bruce = 40.3, Balke = 38.4, and Bike = 36.6 ml/kg·min^?1). Maximum heart rate (HR max) was significantly lower during Bike (178 beats/min) than during Bruce (182) and Balke (183) protocols. No differences in rate of increase in HR or systolic blood pressure (BP) per increase in multiples of the rest metabolic (METs) were found between Bruce and Balke protocols. The rate of recovery of HR and systolic BP was not different among tests. Comparisons of active and sedentary groups showed differences in VO₂ max and submaximal HR and recovery HR at common minutes; however, the rate of increase in HR and systolic BP during exercise and the rate of decrease during recovery were not significantly different. Prediction of VO₂ max with Bruce and Balke protocols from treadmill time was r = 0.91 (SEE ± 2.7 ml/kg·min^?1) and r = 0.94 (SEE 2.2 ml/kg·min^?1), respectively. These data suggest a difference between men and women in increased HR and systolic BP per METs increase in exertion.     

Reduction of submaximal exercise myocardial oxygen demand post-walk training program in coronary patients due to improved physical work efficiency

To assess the effects of walk training on external work efficiency and the determinants of myocardial oxygen demand (MVO₂), we measured total somatic oxygen consumption (VO₂), heart rate (HR), and systolic blood pressure (SBP) in eight male coronary (CAD) patients during submaximal treadmill walking before and after at least 14 weeks of prescribed exercise. Each patient was tested before and after training at the individually determined horizontal treadmill speed that induced ischemic ST segment depression in the pretraining test. Although maximal oxygen uptake (VO₂ max) did not increase significantly with training, submaximal exercise HR and the product of HR and SBP were significantly (p < 0.05) reduced by 10% (120 → 108/min) and 16% (185 × 10² → 156 × 10²), respectively, and none of the patients had ischemic ECG changes after training. The reductions in the cardiac response to exercise were due primarily to a 10% decrease (18.9 → 17.1 ml/kg/min, p < 0.05) in somatic oxygen requirements (VO₂), indicating that the patients became more efficient walkers and reduced their MVO₂ in proportion to the decreased total VO₂. Thus, enhancement of external work efficiency, an extracardiac factor, can lessen myocardial energy costs (MVO₂) and thereby raise the exercise threshold for cardiac ischemia in CAD patients even when aerobic capacity (VO₂ max) is not increased.     

Effects of percutaneous transvenous mitral commissurotomy on levels of plasma atrial natriuretic peptide during exercise.

To clarify the factors that influenced the secretion of human atrial natriuretic peptide (ANP) during exercise, we studied the relations between the changes in ANP, transmitral pressure gradient, heart rate and blood pressure at exercise in 16 patients with mitral stenosis before and after percutaneous transvenous mitral commissurotomy (PTMC). Before PTMC, ANP levels increased from 107 +/- 70 to 183 +/- 96 pg/ml during exercise testing (p less than 0.01), concomitant with the increment in mean transmitral pressure gradient, heart rate and systolic blood pressure. After PTMC, ANP levels also increased from 78 +/- 43 to 117 +/- 64 pg/ml, concomitant with the increment of those parameters. However, increments of ANP, mean transmitral pressure gradient and heart rate after PTMC were lower than those before PTMC. Because the most important factor influencing the secretion of ANP was unclear, the differences between these parameters were calculated at submaximal exercise before and after PTMC. There was a significant relation only between the change in ANP and mean transmitral pressure gradient (r = 0.70, p less than 0.01). These results suggest that the most important factor influencing the secretion of ANP during exercise is the change in transmitral pressure gradient in patients with mitral stenosis.     

Augmented response in plasma brain natriuretic peptide to dynamic exercise in patients with left ventricular dysfunction and congestive heart failure

OBJECTIVES: We have previously demonstrated that patients with symptomatic congestive heart failure (CHF), but not with asymptomatic left ventricular dysfunction (LVD), have augmented plasma atrial natriuretic peptide (ANP) response to exercise. Plasma brain natriuretic peptide (BNP) response to exercise is less extensively studied. The aim of this study was to determine whether responses of plasma BNP during exercise normalized for exercise workload are altered in patients with LVD and CHF. SUBJECTS AND METHODS: Twenty-nine patients with LVD, 32 patients with CHF (NYHA classes II-III) and 27 age-matched control subjects were studied. Ventilatory, plasma ANP and BNP responses were assessed during symptom-limited cardiopulmonary exercise testing. Plasma natriuretic peptide levels were measured at rest and immediately after peak exercise. The increment in plasma BNP was divided by the increment in oxygen uptake (VO2) from rest to peak exercise, and this ratio [BNP exercise ratio: (peak BNP - rest BNP)/(peak VO2 - rest VO2)] was compared amongst the three groups. RESULTS: Peak VO2 (Control, LVD and CHF: 28.2 +/- 1.7, 21.1 +/- 1.8, 16.2 +/- 0.6 ml, min(-1) kg(-1), respectively), anaerobic threshold and peak workload became smaller as heart failure worsened. Resting and peak plasma ANP levels were significantly higher only in CHF, whilst resting and peak plasma BNP levels displayed a significant and continuous increase from normal subjects to LVD and CHF. The ANP exercise ratio (1.25 +/- 0.36, 2.61 +/- 0.57, 7.72 +/- 1.65, ANOVA P = 0.0002) was significantly higher only in patients with CHF, whilst the BNP exercise ratio (0.35 +/- 0.10, 2.60 +/- 0.69, 4.98 +/- 0.97, ANOVA P = 0.0001) was significantly higher in patients with LVD and became progressively higher in patients with CHF. CONCLUSIONS: These data showed that the BNP exercise ratio, an exercise plasma BNP response normalized with exercise workload, was augmented in patients with LVD, and became progressively higher in CHF, suggesting that an augmented exercise BNP ratio exists early in the course of developing CHF.     

Effects of chronic smoking on exercise tolerance and on heart rate-systolic blood pressure product in young healthy adults.

BACKGROUND: Smoking is a major cause of cardiovascular disease and mortality. Smoking-related deaths in Greece account for 23%, whereas 41% of young Greeks are smokers, the highest percentage in Europe. The purpose of this study was to examine the effects of chronic smoking on the rate-pressure product and exercise tolerance in young, healthy male smokers. DESIGN AND METHODS: Forty-two smokers and 51 nonsmokers were selected from a population of 543 students based on their age, sex, body mass index, physical fitness, smoking habit and health status. All participants were tested with the standard Bruce treadmill protocol. The rate-pressure product was obtained at rest and during exercise at a given submaximal workload. The evaluation of exercise tolerance was based on peak workload achieved and maximal exercise test duration. RESULTS: The smokers had a higher rate-pressure product at rest (P<0.001) due to their higher resting heart rate (P<0.001). Resting values of blood pressure did not differ significantly between the two groups. During exercise, smokers had a greater rate-pressure product (P<0.001), mainly due to their significantly higher systolic blood pressure (P=0.008). The smokers had a higher submaximal heart rate (P=0.005), but the differences in heart rate between groups were reduced for smokers during exercise when compared to rest. The smokers' exercise tolerance was impaired and their maximal exercise test duration time was significantly shorter (P<0.001). CONCLUSIONS: Chronic smoking was found to affect young male smokers' cardiovascular fitness, impairing the economy and decreasing the capacity of their circulatory system.     

B-type natriuretic peptide kinetics and cardiopulmonary exercise testing in heart failure

BackgroundIn patients with chronic heart failure (CHF), B-type natriuretic peptide (BNP) is related to peak oxygen consumption (peak VO₂) and the relationship between minute ventilation and carbon dioxide production (VE/VCO₂ slope). However, the exercise response depends on the mode of exercise. This study sought to compare peak treadmill and bicycle exercise responses with respect to their relationship with BNP and to assess whether BNP measured at rest or during exercise could identify patients with greater functional impairment and ventilatory inefficiency.MethodsTwenty-three patients with mild-to-moderate stable systolic CHF (age 72 ± 8 years, left ventricular ejection fraction 32 ± 7%) underwent treadmill and bicycle cardiopulmonary exercise testing within 5 (interquartile range 3–7) days. BNP was measured at rest and at peak exercise.ResultsBNP at rest was an independent multivariate predictor of both peak VO₂ and the VE/VCO₂ slope for both exercise modes. However, the proportion of variance explained univariately and multivariately was ≤ 0.55, indicating that BNP did not strongly explain the variation of peak VO₂ and the VE/VCO₂ slope. The exercise-induced rise in circulating BNP did not differ between the test modes [treadmill: 50 (24–89) pg/ml vs. bicycle: 46 (15–100) pg/ml; p = 0.73]. BNP levels at peak exercise were strongly related to resting values, but did not provide additional information on peak VO₂ or the VE/VCO₂ slope.ConclusionsIn typical CHF patients, BNP measured at rest or at peak exercise does not strongly predict peak VO₂ or the VE/VCO₂ slope regardless of the exercise mode, and is therefore not a sufficiently accurate surrogate for cardiopulmonary exercise testing.     

Blood glucose response to aerobic exercise training program among patients with type 2 diabetes mellitus at the University of Nigeria Teaching Hospital,Enugu South-East,Nigeria

Control of all types of diabetes involves maintaining normal or near-normal blood glucose levels through the appropriate therapy: insulin, oral hypoglycemic agents, diet, and exercise. The aim of this study was to investigate the blood glucose response to aerobic exercise training among subjects with type 2 diabetes mellitus at University of Nigeria Teaching Hospital (UNTH), Enugu. Age-matched randomized controlled trial design was used; subjects with diagnosis of type 2 diabetes mellitus attending the diabetes clinic of the UNTH participated in the study. Fifty-four subjects (N = 54) with type 2 diabetes mellitus (fasting blood sugar (FBS) of between 110 and 225 mg/dl) were age-matched and randomized into two groups: exercise (n = 30) and control (n = 24) groups. The exercise group was involved in an 8-week continuous training (60–79 % heart rate (HR) max) of between 45 and 60 min, three times per week, while the control group remained sedentary. Systolic blood pressure (SBP), diastolic blood pressure (DBP), VO₂ max, and FBS were assessed. Analysis of co-variance and Pearson correlation tests were used in data analysis. Findings of the study revealed significant effect of exercise training program on SBP, DBP, FBS, and VO₂ max. Changes in VO₂ max significantly and negatively correlated with changes in FBS (r = −.220) at p < 0.05. It was concluded that aerobic exercise program is an effective adjunct therapy in controlling blood glucose level among type 2 diabetic subjects.

     

Exaggerated atrial natriuretic peptide release during acute exercise in essential hypertension

The effects of acute exercise on plasma concentrations of atrial natriuretic peptide (ANP), arginine vasopressin (AVP), and plasma renin activity (PRA) were studied in 13 patients with previously untreated essential hypertension, and 8 matched normotensive control subjects. Resting levels of ANP and PRA were similar in the two groups, while resting AVP concentrations were 1.4 times higher in hypertensive subjects. Graded exercise was performed on a bicycle ergometer with workload increased each minute until exhaustion (Wmax). Wmax was higher in normal subjects than in hypertensive patients. Blood pressure and heart rate rose more steeply in hypertensive patients. Plasma ANP increased during acute exercise in both groups, but the average increase in hypertensives was substantially greater than in normal subjects (P less than 0.05). The increase in ANP during exercise was greater in hypertensives with left ventricular (LV) hypertrophy, and there was a positive correlation between LV mass and the percentage rise in ANP during exercise (r = 0.56, P less than 0.005). Plasma AVP did not alter during exercise. Plasma renin concentrations showed a small rise during exercise in both groups, which was 16% less in hypertensive subjects (P less than 0.05). The enhancement of ANP release during exercise in hypertensive subjects may reflect both cardiac structural changes and increased redistribution of blood to the cardiopulmonary compartment.     

Effects of antihypertensive agents on blood pressure during exercise.

The relationship between blood pressure (BP) and cardiovascular morbidity has been appreciated for many years. Casual BP may not be representative of the pressure at other times. It is recognized that BP during exercise may be a more accurate predictor than casual BP. There is, however, little information about the effects of antihypertensive drugs on the BP during exercise. This study was designed to investigate the effects of various antihypertensive agents on BP during exercise. Sixty-four patients (age, 49+/-10 years) with untreated essential hypertension (WHO I, II) were studied during a supine ergometric exercise regimen. A graded exercise test was started at a workload of 50 W, and the load was increased by 25 W every 3 min. The hemodynamic responses to exercise were evaluated by changes in systolic and diastolic BP (SBP, DBP) and heart rate (HR). Plasma norepinephrine (NE) levels were measured at rest and during submaximal exercise, and before and after 4 weeks of treatment with metoprolol (METO), doxazosin (DOXA), trichlormethiazide (TCTZ), nifedipine (NIFE), amlodipine (AMLO) and temocapril (TEMO) between left ventricular mass index (LVMI) and BP values at rest, during exercise, and during the recovery period after exercise were assessed by multiple regression analysis. The stepwise selection (forward conditional) method showed that LVMI was significantly associated with SBP during submaximal exercise and during the recovery period. All antihypertensive treatments decreased SBP and DBP (p<0.01) at rest. METO, AMLO and TEMO significantly lowered SBP (p<0.05) during exercise, whereas DOXA, TCTZ and NIFE induced no change in SBP. The exercise-induced increase of plasma NE was further enhanced by METO and NIFE but not by AMLO, DOXA, or TCTZ, and it was significantly suppressed by TEMO (p<0.01). These results suggest that BP during exercise is more highly associated with the progression of left ventricular hypertrophy (LVH) than is casual BP. Because antihypertensive agents differ in their effects on exercise hemodynamics, we recommend that hemodynamic factors during exercise be considered when selecting the optimal antihypertensive medication for highly active patients.     

Cardiac function and maximal exercise capacity early after acute myocardial infarction

The purpose of the study was to assess the relationship betweenleft and right ventricular function measured at rest and maximalexercise capacity in patients with recent acute myocardial infarction(AMI). Forty-three male patients (Killip Class I, n=36; KillipClass II, n=7) with a wide range of left ventricular (LV) functionand size underwent graded bicycle exercise testing less than4 weeks after AMI (mean 21 days, 17–27). None of the patientshad exercise limiting factors other than dyspnoea and fatigue.Left and right ventricular ejection fractions were determinedby a radionuclide ventriculo graphic method which also alloweddetermination of absolute LV volumes and actual LV peak fillingrate. LV ejection fraction had a tt weak association to estimatedmaximal oxygen uptake (VO₂ max) (r=0·37). No associationwas found between LV size, LV stroke volume, or LV peak fillingrate and estimated VO₂ max. Similarly, right ventricular ejectionfraction showed no correlation to estimated VO₂ max. Patientswith well preserved LV function had a higher exercise inducedincrease in systolic blood pressure than patients with reducedLV function, but the increase in systolic blood pressure couldnot be used to estimate LV function with any reasonable accuracy. We conclude that the maximal exercise capacity of patients withrecent AMI is virtually independent of their left and rightventricular function determined at rest, and that exercise testingand radionuclide ventriculography should be regarded as complementaryprocedures in the evaluation of patients with AMI.