Renin angiotensin system and cardiac hypertrophy after sinoaortic denervation in rats

OBJECTIVE:

The aim of this study was to evaluate the role of angiotensin I, II and 1–7 on left ventricular hypertrophy of Wistar and spontaneously hypertensive rats submitted to sinoaortic denervation.

METHODS:

Ten weeks after sinoaortic denervation, hemodynamic and morphofunctional parameters were analyzed, and the left ventricle was dissected for biochemical analyses.

RESULTS:

Hypertensive groups (controls and denervated) showed an increase on mean blood pressure compared with normotensive ones (controls and denervated). Blood pressure variability was higher in denervated groups than in their respective controls. Left ventricular mass and collagen content were increased in the normotensive denervated and in both spontaneously hypertensive groups compared with Wistar controls. Both hypertensive groups presented a higher concentration of angiotensin II than Wistar controls, whereas angiotensin 1–7 concentration was decreased in the hypertensive denervated group in relation to the Wistar groups. There was no difference in angiotensin I concentration among groups.

CONCLUSION:

Our results suggest that not only blood pressure variability and reduced baroreflex sensitivity but also elevated levels of angiotensin II and a reduced concentration of angiotensin 1–7 may contribute to the development of left ventricular hypertrophy. These data indicate that baroreflex dysfunction associated with changes in the renin angiotensin system may be predictive factors of left ventricular hypertrophy and cardiac failure.     

Low-Intensity physical activity beneficially alters the ultrastructural renal morphology of spontaneously hypertensive rats

INTRODUCTION AND OBJECTIVE:

Kidney disorders can cause essential hypertension, which can subsequently cause renal disease. High blood pressure is also common among those with chronic kidney disease; moreover, it is a well-known risk factor for a more rapid progression to kidney failure. Because hypertension and kidney function are closely linked, the present study aimed to observe the beneficial effects of low-intensity physical activity on structural and ultrastructural renal morphology and blood pressure in normotensive and spontaneously hypertensive rats.

METHOD:

Male Wistar-Kyoto rats and spontaneously hypertensive rats were randomly allocated into four groups: sedentary or exercised Wistar-Kyoto and sedentary or exercised spontaneously hypertensive rats. The exercise lasted 20 weeks and consisted of treadmill training for 1 hour/day, 5 days/week.

RESULTS:

The exercised, spontaneously hypertensive rats showed a significant blood pressure reduction of 26%. The body masses of the Wistar-Kyoto and spontaneously hypertensive strains were significantly different. There were improvements in some of the renal structures of the animals treated with physical activity: (i) the interdigitations of the proximal and distal convoluted tubules; (ii) the basal membrane of the proximal and distal convoluted tubules; and (iii) in the basal membrane, slit diaphragm and pedicels of the glomerular filtration barrier. The spontaneously hypertensive rats also showed a decreased expression of connexin-43.

CONCLUSION:

Physical exercise could be a therapeutic tool for improving kidney ultrastructure and, consequently, renal function in hypertensive individuals.     

The Clinical Association of the Blood Pressure Variability with the Target Organ Damage in Hypertensive Patients with Chronic Kidney Disease

It is known that blood pressure variability (BPV) can independently affect target organ damage (TOD), even with normal blood pressure. There have been few studieson chronic kidney disease (CKD) patients. We evaluated the relationship between BPV and TOD in a cross-sectional, multicenter study on hypertensive CKD patients. We evaluated 1,173 patients using 24-hr ambulatory blood pressure monitoring. BPV was defined as the average real variability, with a mean value of the absolute differences between consecutive readings of systolic blood pressure. TOD was defined as left ventricular hypertrophy (LVH) (by the Romhilt-Estes score ≥4 in electrocardiography) and kidney injury (as determined from an estimated glomerular filtration rate [eGFR]<30 mL/min/1.73 m² and proteinuria).The mean BPV of the subjects was 15.9±4.63 mmHg. BPV displayed a positive relationship with LVH in a univariate analysis and after adjustment for multi-variables (odds ratio per 1 mmHg increase in BPV: 1.053, P=0.006). In contrast, BPV had no relationship with kidney injury. These data suggest that BPV may be positively associated with LVH in hypertensive CKD patients.

Graphical Abstract

相似文献   

Relationship between Blood Pressure Variability and the Quality of Life

Purpose

Blood pressure variability (BPV) is emerging as an important cardiovascular prognostic factor in addition to average blood pressure level. While there have been some suggestions for the determinants of the blood pressure variability, little is known about the relationship between the blood pressure variability and health-related quality of life (QOL).

Materials and Methods

Fifty-six men and women with mild hypertension were enrolled from local health centers in Republic of Korea, from April to October 2009. They self-monitored their blood pressure twice daily for 8 weeks. Pharmacological treatment was not changed during the period. Standard deviation and coefficient of variation of blood pressure measurements were calculated as indices of BPV. Measurements of QOL were done at initial and at 8-week follow-up visits.

Results

Study subjects had gender ratio of 39:41 (male:female) and the mean age was 64±10 years. The mean home blood pressure''s at week 4 and 8 did not differ from baseline. Total score of QOL at follow-up visit and change of QOL among two measurements were negatively correlated to BPV indices, i.e., higher QOL was associated with lower BPV. This finding persisted after adjustment for age, gender and the number of antihypertensive agents. Among dimensions of QOL, physical, mental and hypertension-related dimensions were associated particularly with BPV.

Conclusion

QOL may be a significant determinant of BPV. Improvement of QOL may lead to favorable changes in BPV.     

Aerobic exercise training induces metabolic benefits in rats with metabolic syndrome independent of dietary changes

OBJECTIVES:

We evaluated the effects of aerobic exercise training without dietary changes on cardiovascular and metabolic variables and on the expression of glucose transporter Type 4 in rats with metabolic syndrome.

METHODS:

Twenty male spontaneously hypertensive rats received monosodium glutamate during the neonatal period. The animals were allocated to the following groups: MS (sedentary metabolic syndrome), MS-T (trained on a treadmill for 1 hour/day, 5 days/week for 10 weeks), H (sedentary spontaneously hypertensive rats) and H-T (trained spontaneously hypertensive rats). The Lee index, blood pressure (tail-cuff system), insulin sensitivity (insulin tolerance test) and functional capacity were evaluated before and after 10 weeks of training. Glucose transporter Type 4 expression was analyzed using Western blotting. The data were compared using analysis of variance (ANOVA) (p<0.05).

RESULTS:

At baseline, the MS rats exhibited lower insulin sensitivity and increased Lee index compared with the H rats. Training decreased the body weight and Lee index of the MS rats (MS-T vs. MS), but not of the H rats (H-T vs. H). There were no differences in food intake between the groups. At the end of the experiments, the systolic blood pressure was lower in the two trained groups than in their sedentary controls. Whole-body insulin sensitivity increased in the trained groups. Glucose transporter Type 4 content increased in the heart, white adipose tissue and gastrocnemius muscle of the trained groups relative to their respective untrained groups.

CONCLUSION:

In conclusion, the present study shows that an isolated aerobic exercise training intervention is an efficient means of improving several components of metabolic syndrome, that is, training reduces obesity and hypertension and increases insulin sensitivity.     

Effects of spironolactone in spontaneously hypertensive adult rats subjected to high salt intake

OBJECTIVE:

To evaluate the effect of spironolactone on ventricular stiffness in spontaneously hypertensive adult rats subjected to high salt intake.

INTRODUCTION:

High salt intake leads to cardiac hypertrophy, collagen accumulation and diastolic dysfunction. These effects are partially mediated by cardiac activation of the renin-angiotensin-aldosterone system.

METHODS:

Male spontaneously hypertensive rats (SHRs, 32 weeks) received drinking water (SHR), a 1% NaCl solution (SHR-Salt), or a 1% NaCl solution with a daily subcutaneous injection of spironolactone (80 mg.kg^-1) (SHR-Salt-S). Age-matched normotensive Wistar rats were used as a control. Eight weeks later, the animals were anesthetized and catheterized to evaluate left ventricular and arterial blood pressure. After cardiac arrest, a double-lumen catheter was inserted into the left ventricle through the aorta to obtain in situ left ventricular pressure-volume curves.

RESULTS:

The blood pressures of all the SHR groups were similar to each other but were different from the normotensive controls (Wistar  =  109±2; SHR  =  118±2; SHR-Salt  =  117±2; SHR-Salt-S  =  116±2 mmHg; P<0.05). The cardiac hypertrophy observed in the SHR was enhanced by salt overload and abated by spironolactone (Wistar  =  2.90±0.06; SHR  =  3.44±0.07; SHR-Salt  =  3.68±0.07; SHR-Salt-S  =  3.46±0.05 mg/g; P<0.05). Myocardial relaxation, as evaluated by left ventricular dP/dt, was impaired by salt overload and improved by spironolactone (Wistar  =  -3698±92; SHR  =  -3729±125; SHR-Salt  =  -3342±80; SHR-Salt-S  =  -3647±104 mmHg/s; P<0.05). Ventricular stiffness was not altered by salt overload, but spironolactone treatment reduced the ventricular stiffness to levels observed in the normotensive controls (Wistar  =  1.40±0.04; SHR  =  1.60±0.05; SHR-Salt  =  1.67±0.12; SHR-Salt-S  =  1.45±0.03 mmHg/ml; P<0.05).

CONCLUSION:

Spironolactone reduces left ventricular hypertrophy secondary to high salt intake and ventricular stiffness in adult SHRs.     

Endothelial and Non-Endothelial Coronary Blood Flow Reserve and Left Ventricular Dysfunction in Systemic Hypertension

OBJECTIVES:

We evaluated the impairment of endothelium-dependent and endothelium-independent coronary blood flow reserve after administration of intracoronary acetylcholine and adenosine, and its association with hypertensive cardiac disease.

INTRODUCTION:

Coronary blood flow reserve reduction has been proposed as a mechanism for the progression of compensated left ventricular hypertrophy to ventricular dysfunction.

METHODS:

Eighteen hypertensive patients with normal epicardial coronary arteries on angiography were divided into two groups according to left ventricular fractional shortening (FS). Group 1 (FS ≥0.25): n=8, FS=0.29 ± 0.03; Group 2 (FS <0.25): n=10, FS= 0.17 ± 0.03.

RESULTS:

Baseline coronary blood flow was similar in both groups (Group 1: 80.15 ± 26.41 mL/min, Group 2: 100.09 ± 21.51 mL/min, p=NS). In response to adenosine, coronary blood flow increased to 265.1 ± 100.2 mL/min in Group 1 and to 300.8 ± 113.6 mL/min (p <0.05) in Group 2. Endothelium-independent coronary blood flow reserve was similar in both groups (Group 1: 3.31 ± 0.68 and Group 2: 2.97 ± 0.80, p=NS). In response to acetylcholine, coronary blood flow increased to 156.08 ± 36.79 mL/min in Group 1 and to 177.8 ± 83.6 mL/min in Group 2 (p <0.05). Endothelium-dependent coronary blood flow reserve was similar in the two groups (Group 1: 2.08 ± 0.74 and group Group 2: 1.76 ± 0.61, p=NS). Peak acetylcholine/peak adenosine coronary blood flow response (Group 1: 0.65 ± 0.27 and Group 2: 0.60 ± 0.17) and minimal coronary vascular resistance (Group 1: 0.48 ± 0.21 mmHg/mL/min and Group 2: 0.34 ± 0.12 mmHg/mL/min) were similar in both groups (p= NS). Casual diastolic blood pressure and end-systolic left ventricular stress were independently associated with FS.

CONCLUSIONS:

In our hypertensive patients, endothelium-dependent and endothelium-independent coronary blood flow reserve vasodilator administrations had similar effects in patients with either normal or decreased left ventricular systolic function.     

Gender specific pattern of left ventricular cardiac adaptation to hypertension and obesity in a tertiary health facility in Nigeria

Background

Cardiac adaptation to hypertension and obesity may be related to many factors such as race, gender and haemodynamic status. Some gender specific associations with left ventricular structure and function have been described among Caucasians.

Objectives

To describe the sex specific pattern of left ventricular adaptations to obesity and hypertension among Nigerians.

Methodology

It was a cross sectional study carried out at LAUTECH Teaching Hospital, Osogbo, Nigeria. 313 subjects had full echocardiography performed. Participants were divided into four groups: normal, obese, hypertensives and obese-hypertensives. Indices of LV adaptation were compared between the groups. SPSS 16.0 was used for analysis.

Results

Relative to normal subjects, LV mass (LVM), LV mass index (LVMI) and wall thickness were significantly higher among hypertensive men and obese hypertensive men. They were similar between normal and obese men. However, LVM, LVMI and wall thickness were increased among obese women compared to normal women while they were similar among obese, hypertensive and obese-hypertensive women. Men with concurrent obesity and hypertension presented with a further increase of LVM and wall thickness above values in the merely obese or hypertensive subjects. Female obesehypertensive seem to present more with eccentric hypertrophy than male obese-hypertensive subjects (17.2% vs. 9.1% respectively, p<0.05) while male obese-hypertensive seem to present more with concentric hypertrophy (54.5% vs. 43.1% respectively, p>0.05) than female obese-hypertensive subjects.

Conclusion

Structural, functional and geometric LV adaptation to obesity and hypertension varies between the two genders among Nigerians. The impact of isolated obesity on LV adaptation in women appears very significant.     

Effects of the administration of a catalase inhibitor into the fourth cerebral ventricle on cardiovascular responses in spontaneously hypertensive rats exposed to sidestream cigarette smoke

OBJECTIVE:

Previous studies have demonstrated a relationship between brain oxidative stress and cardiovascular regulation. We evaluated the effects of central catalase inhibition on cardiovascular responses in spontaneously hypertensive rats exposed to sidestream cigarette smoke.

METHODS:

Male Wistar Kyoto (WKY) rats and spontaneously hypertensive rats (SH) (16 weeks old) were implanted with a stainless steel guide cannula leading into the fourth cerebral ventricle (4^th V). The femoral artery and vein were cannulated for arterial pressure and heart rate measurement and drug infusion, respectively. The rats were exposed to sidestream cigarette smoke for 180 minutes/day, 5 days/week for 3 weeks (CO: 100-300 ppm). The baroreflex was tested using a pressor dose of phenylephrine (8 μg/kg, bolus) and a depressor dose of sodium nitroprusside (50 μg/kg, bolus). Cardiovascular responses were evaluated before and 5, 15, 30 and 60 minutes after injection of a catalase inhibitor (3-amino-1,2,4-triazole, 0.001 g/100 μL) into the 4^th V.

RESULTS:

Vehicle administration into the 4^th V did not affect the cardiovascular response, whereas administration of the central catalase inhibitor increased the basal HR and attenuated the bradycardic peak (p<0.05) to a greater extent in WKY rats exposed to sidestream cigarette smoke than in WKY rats exposed to fresh air. However, in spontaneously hypertensive rats, the effect of the catalase inhibitor treatment was stronger in the fresh air condition (p<0.05).

CONCLUSION:

Administration of a catalase inhibitor into the 4^th V combined with exposure to sidestream cigarette smoke has a stronger effect in WKY rats than in SH rats.     

Dysregulation of Heart Rhythm During Sleep in Leptin-Deficient Obese Mice

Study Objectives:

Sleep deeply affects cardiac autonomic control, the impairment of which is associated with cardiovascular mortality. Obesity entails increased cardiovascular risk and derangements in sleep and cardiac autonomic control. We investigated whether cardiac autonomic control is impaired during sleep in ob/ob mice with morbid obesity caused by congenital leptin deficiency.

Design:

Indexes of cardiac autonomic control based on spontaneous cardiovascular fluctuations were compared between ob/ob and lean wild-type (+/+) mice during wakefulness, non-rapid eye movement sleep (NREMS), and rapid eye movement sleep (REMS).

Setting:

N/A

Patients or Participants:

7 ob/ob and 11 +/+ male mice.

Interventions:

Instrumentation with electrodes for sleep recordings and a telemetric transducer for measuring blood pressure and heart period.

Measurements and Results:

In ob/ob mice, the variability of heart period and cardiac baroreflex sensitivity (sequence technique) were significantly lower than in +/+ mice during each wake-sleep state. The vagal modulation of heart period was significantly weaker in ob/ob than in +/+ mice during NREMS and REMS. In ob/ob mice, the cross-correlation function between heart period and blood pressure suggested that the baroreflex contribution to cardiac control was lower than in +/+ mice during wakefulness and NREMS, whereas the contribution of central autonomic commands was lower than in +/+ mice during NREMS and REMS.

Conclusions:

These data indicate a dysregulation of cardiac autonomic control during sleep in ob/ob mice. Ob/ob mice may represent a useful tool to understand the molecular pathways that lead to cardiac autonomic dysregulation during sleep in obesity.

Citation:

Silvani A; Bastianini S; Berteotti C; Franzini C; Lenzi P; Lo Martire V; Zoccoli G. Dysregulation of heart rhythm during sleep in leptin-deficient obese mice. SLEEP 2010;33(3):355-361.     

Short-Term Red Wine Consumption Promotes Differential Effects on Plasma Levels of High-Density Lipoprotein Cholesterol, Sympathetic Activity, and Endothelial Function in Hypercholesterolemic, Hypertensive, and Healthy Subjects

OBJECTIVES:

To compare the metabolic, hemodynamic, autonomic, and endothelial responses to short-term red wine consumption in subjects with hypercholesterolemia or arterial hypertension, and healthy controls.

METHODS:

Subjects with hypercholesterolemia (n=10) or arterial hypertension (n=9), or healthy controls (n=7) were given red wine (250 mL/night) for 15 days. Analyses were performed before and after red wine intake.

RESULTS:

Red wine significantly increased the plasma levels of HDL-cholesterol in the controls, but not in the other groups. The effects on hemodynamic measurements were mild, non-significantly more prominent in healthy subjects, and exhibited high interindividual variability. Across all participants, mean blood pressure decreased 7 mmHg (p <0.01) and systemic vascular resistance decreased 7% (p = 0.05). Heart rate and cardiac output did not significantly change in any group. Red wine enhanced muscle sympathetic fibular nerve activity in hypercholesterolemic and hypertensive patients, but not in controls. At baseline, brachial artery flow-mediated dilation was impaired in patients with hypercholesterolemia and arterial hypertension; red wine restored the dilation in the hypercholesterolemic group but not in the hypertensive group.

CONCLUSIONS:

Red wine elicits different metabolic, autonomic, and endothelial responses among individuals with hypercholesterolemia or arterial hypertension and healthy controls. Our findings highlight the need to consider patient characteristics when evaluating the response to red wine.     

Aerobic exercise improves the inflammatory profile correlated with cardiac remodeling and function in chronic heart failure rats

OBJECTIVE:

The aim of the present study was to evaluate the effect of 8 weeks of aerobic exercise training on cardiac functioning and remodeling and on the plasma levels of inflammatory cytokines in chronic heart failure rats.

METHODS:

Wistar rats were subjected to myocardial infarction or sham surgery and assigned to 4 groups: chronic heart failure trained (n = 7), chronic heart failure sedentary (n = 6), sham trained (n = 8) and sham sedentary (n = 8). Four weeks after the surgical procedures, the rats were subjected to aerobic training in the form of treadmill running (50 min/day, 5 times per week, 16 m/min). At the end of 8 weeks, the rats were placed under anesthesia, the hemodynamic variables were recorded and blood samples were collected. Cardiac hypertrophy was evaluated using the left ventricular weight/body weight ratio, and the collagen volume fraction was assessed using histology.

RESULTS:

The chronic heart failure trained group showed a reduction in left ventricular end-diastolic pressure, a lower left ventricular weight/body weight ratio and a lower collagen volume fraction compared with the chronic heart failure sedentary group. In addition, exercise training reduced the plasma levels of TNF-α and IL-6 and increased the plasma level of IL-10.

CONCLUSION:

An 8-week aerobic exercise training program improved the inflammatory profile and cardiac function and attenuated cardiac remodeling in chronic heart failure rats.     

Prevalence of left ventricular diastolic dysfunction in newly diagnosed Nigerians with systemic hypertension: a pulsed wave Doppler echocardiographic study

Background

Systemic hypertension is a common cause of left ventricular diastolic dysfunction. However, its prevalence in Nigerians with untreated systemic hypertension is unknown.

Objective

To determine the prevalence of left ventricular diastolic dysfunction in newly diagnosed Nigerians with systemic hypertension using Doppler transmitral inflow and pulmonary venous flow velocities.

Methods

Two-dimensional echocardiography including Doppler was performed on 150 newly diagnosed cases of systemic hypertension and 150 normotensive controls. They were divided into hypertensives without left ventricular hypertrophy and those with left ventricular hypertrophy based on echocardiographically determined left ventricular mass index. Pulsed Doppler transmitral inflow and the pulmonary venous flow waves were used to categorise the patterns of diastolic dysfunction.

Results

The hypertensives and the normotensive controls were comparable in their baseline characteristics. The E/A ratio differed significantly between hypertensives with and without left ventricular hypertrophy and controls (1.00+0.30, 1.04±0.42, 1.33±0.27, p < 0.001). Left ventricular diastolic dysfunction occurred in 62% of systemic hypertension and 11.3% of the controls. Impaired relaxation was the commonest pattern (84.9%) of diastolic dysfunction.

Conclusion

Our study showed that left ventricular diastolic dysfunction is prevalent in Nigerians with newly diagnosed systemic hypertension and effort should be made to routinely screen for them.     

Effect of GPE-AGT nanoparticle shRNA transfection system mediated RNAi on early atherosclerotic lesion

Objective

To investigate the effects of RNA interference targeting AGT on early atherosclerotic lesion in the hypertensive state.

Methods

Hypertension and atherosclerosis rats were treated with GPE nanoparticles carrying AGT shRNA. Systolic blood pressure and heart rate were measured for 2 consecutive weeks. Three days after treatment, the mRNA and protein expressions of AGT in the liver were measured by PCR and western blot assay, respectively. The blood levels of AGT and Ang II were determined by ELISA. H&E staining and electron microscopy were performed.

Results

Three days after AGT shRNA treatment, the mRNA and protein expressions of AGT in the liver were markedly reduced and the blood levels of AGT and Ang II dramatically decreased as compared to the remaining 3 groups (P < 0.05). Three days after AGT shRNA treatment, the blood pressure was reduced by 27 ± 4mmHg when compared with that at baseline (P < 0.05). About 11 days after AGT shRNA treatment, the blood pressure began to increase. The blood pressure remained unchanged in the remaining 3 groups. Microscopy showed the atherosclerotic lesions were markedly attenuated in AGT shRNA treated rats but the liver and kidney functions remained stable (P > 0.05) when compared with the remaining 3 groups.

Conclusion

Transfection with GPE nanoparticle carrying AGT shRNA can stably lower the blood pressure and improve the atherosclerotic lesions which lead to the delayed development of early atherosclerotic lesions in hypertension rats with concomitant atherosclerosis.     

Anti-Hypertensive Drugs Have Different Effects on Ventricular Hypertrophy Regression

OBJECTIVES:

There is a direct relationship between the regression of left ventricular hypertrophy (LVH) and a decreased risk of mortality. This investigation aimed to describe the effects of anti-hypertensive drugs on cardiac hypertrophy through a meta-analysis of the literature.

METHODS:

The Medline (via PubMed), Lilacs and Scielo databases were searched using the subject keywords cardiac hypertrophy, antihypertensive and mortality. We aimed to analyze the effect of anti-hypertensive drugs on ventricle hypertrophy.

RESULTS:

The main drugs we described were enalapril, verapamil, nifedipine, indapamina, losartan, angiotensin-converting enzyme inhibitors and atenolol. These drugs are usually used in follow up programs, however, the studies we investigated used different protocols. Enalapril (angiotensin-converting enzyme inhibitor) and verapamil (Ca⁺⁺ channel blocker) caused hypertrophy to regress in LVH rats. The effects of enalapril and nifedipine (Ca⁺⁺ channel blocker) were similar. Indapamina (diuretic) had a stronger effect than enalapril, and losartan (angiotensin II receptor type 1 (AT1) receptor antagonist) produced better results than atenolol (selective β1 receptor antagonist) with respect to LVH regression.

CONCLUSION:

The anti-hypertensive drugs induced various degrees of hypertrophic regression.     

Autonomic cardiovascular tests in children with obstructive sleep apnea syndrome

Study Objectives:

The aim of our study was to investigate cardiovascular autonomic activity during wakefulness, using cardiovascular tests, in a population of children with OSAS.

Design:

Prospective study.

Setting:

Sleep unit of an academic center.

Participants:

We included 25 children (mean age 10.2 ± 2.3 years) undergoing a diagnostic assessment for OSAS, and 25 age-matched healthy control subjects. All subjects underwent an overnight polysomnography and autonomic cardiovascular tests using parts of the Ewing test battery, which is a physiological test used for the assessment of autonomic function (head-up tilt test, Valsalva maneuver, deep breathing test).

Measurements and Results:

Eighteen of 25 children with OSAS (11 males, mean age 9.4 ± 1.7 years) concluded the study. OSAS patients had higher systolic blood pressure, diastolic blood pressure, baseline heart rate, the 30:15 index (which represents the RR interval at the 15th and 30th beats during the head up tilt test), and delta diastolic and systolic blood pressure during the head-up tilt test, while the heart rate variability during the deep breathing test was lower, compared with controls. A positive correlation between systolic and diastolic blood pressure and the apnea-hypopnea index (AHI), and negative between AHI and both the 30:15 index and Valsalva ratio, were found. Stepwise linear regression analysis detected a negative correlation between AHI and the 30:15 index and Valsalva ratio, a positive correlation between overnight mean oxygen saturation and delta heart rate, and between AHI and delta systolic blood pressure.

Conclusions:

Our data point to an increase in basal sympathetic activity during wakefulness and to an impaired reaction to several physiological stimuli, which is dependent on the severity of OSAS.

Citation:

Montesano M; Miano S; Paolino MC; Massolo AC; Ianniello F; Forlani M; Villa MP. Autonomic cardiovascular tests in children with obstructive sleep apnea syndrome. SLEEP 2010;33(10):1349-1355.     

Self-monitoring and other non-pharmacological interventions to improve the management of hypertension in primary care: a systematic review

Background

Patients with high blood pressure (hypertension) in the community frequently fail to meet treatment goals: a condition labelled as ‘uncontrolled’ hypertension. The optimal way to organise and deliver care to hypertensive patients has not been clearly identified.

Aim

To determine the effectiveness of interventions to improve control of blood pressure in patients with hypertension.

Design of study

Systematic review of randomised controlled trials.

Setting

Primary and ambulatory care.

Method

Interventions were categorised as following: self-monitoring; educational interventions directed to the patient; educational interventions directed to the health professional; health professional- (nurse or pharmacist) led care; organisational interventions that aimed to improve the delivery of care; and appointment reminder systems. Outcomes assessed were mean systolic and diastolic blood pressure, control of blood pressure and proportion of patients followed up at clinic.

Results

Seventy-two RCTs met the inclusion criteria. The trials showed a wide variety of methodological quality. Self-monitoring was associated with net reductions in systolic blood pressure (weighted mean difference [WMD] −2.5mmHg, 95%CI = −3.7 to −1.3 mmHg) and diastolic blood pressure (WMD −1.8mmHg, 95%CI = −2.4 to −1.2 mmHg). An organised system of regular review allied to vigorous antihypertensive drug therapy was shown to reduce blood pressure and all-cause mortality in a single large randomised controlled trial.

Conclusion

Antihypertensive drug therapy should be implemented by means of a vigorous stepped care approach when patients do not reach target blood pressure levels. Self-monitoring is a useful adjunct to care while reminder systems and nurse/pharmacist -led care require further evaluation.     

Intra-Arterial Blood Pressure Response in Hypertensive Subjects during Low- and High-Intensity Resistance Exercise

OBJECTIVE:

The aim of this study was to describe blood pressure responses during resistance exercise in hypertensive subjects and to determine whether an exercise protocol alters these responses.

INTRODUCTION:

Resistance exercise has been recommended as a complement for aerobic exercise for hypertensive patients. However, blood pressure changes during this kind of exercise have been poorly investigated in hypertensives, despite multiple studies of normotensives demonstrating significant increases in blood pressure.

METHODS:

Ten hypertensive and ten normotensive subjects performed, in random order, two different exercise protocols, composed by three sets of the knee extension exercise conducted to exhaustion: 40% of the 1-repetition maximum (1RM) with a 45-s rest between sets, and 80% of 1RM with a 90-s rest between sets. Radial intra-arterial blood pressure was measured before and throughout each protocol.

RESULTS:

Compared with normotensives, hypertensives displayed greater increases in systolic BP during exercise at 80% (+80±3 vs. +62±2 mmHg, P<0.05) and at 40% of 1RM (+75±3 vs. +67±3 mmHg, P<0.05). In both exercise protocols, systolic blood pressure returned to baseline during the rest periods between sets in the normotensives; however, in the hypertensives, BP remained slightly elevated at 40% of 1RM. During rest periods, diastolic blood pressure returned to baseline in hypertensives and dropped below baseline in normotensives.

CONCLUSION:

Resistance exercise increased systolic blood pressure considerably more in hypertensives than in normotensives, and this increase was greater when lower-intensity exercise was performed to the point of exhaustion.     

Monosodium glutamate neonatal treatment induces cardiovascular autonomic function changes in rodents

OBJECTIVES:

The aim of this study was to evaluate cardiovascular autonomic function in a rodent obesity model induced by monosodium glutamate injections during the first seven days of life.

METHOD:

The animals were assigned to control (control, n = 10) and monosodium glutamate (monosodium glutamate, n = 13) groups. Thirty-three weeks after birth, arterial and venous catheters were implanted for arterial pressure measurements, drug administration, and blood sampling. Baroreflex sensitivity was evaluated according to the tachycardic and bradycardic responses induced by sodium nitroprusside and phenylephrine infusion, respectively. Sympathetic and vagal effects were determined by administering methylatropine and propranolol.

RESULTS:

Body weight, Lee index, and epididymal white adipose tissue values were higher in the monosodium glutamate group in comparison to the control group. The monosodium glutamate-treated rats displayed insulin resistance, as shown by a reduced glucose/insulin index (-62.5%), an increased area under the curve of total insulin secretion during glucose overload (39.3%), and basal hyperinsulinemia. The mean arterial pressure values were higher in the monosodium glutamate rats, whereas heart rate variability (>7 times), bradycardic responses (>4 times), and vagal (∼38%) and sympathetic effects (∼36%) were reduced as compared to the control group.

CONCLUSION:

Our results suggest that obesity induced by neonatal monosodium glutamate treatment impairs cardiac autonomic function and most likely contributes to increased arterial pressure and insulin resistance.