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1.
BACKGROUND: Ambulatory blood pressure monitoring (ABPM) has been found to be of significant importance in clinical practice because numerous blood pressure (BP) measurements may be made throughout the 24-hour period. OBJECTIVE: To assess the clinical utility of ABPM in children with secondary hypertension. METHODS: We studied 37 patients (21 boys and 16 girls), with a mean age of 16.4 +/- 4.1 years, after kidney transplantation and 38 patients (27 boys and 11 girls), with a mean age of 10.2 +/- 2.1 years, after surgical correction of aortic coarctation. Data, expressed as mean +/- SD, were analyzed after dividing the patients into 4 groups. Group A consisted of 25 patients receiving antihypertensive therapy; group B included 12 patients not receiving antihypertensive therapy. Group C included 25 patients operated on before 3 years of age (8 +/- 7 months of age); group D included 13 patients operated on after 3 years of age (74 +/- 29 months of age). RESULTS: In groups A and B, casual BP measurement showed that 16 of 37 patients (43%) were hypertensive; 24-hour ABPM detected a larger number of patients who were hypertensive (23 of 37, 62%); there were 18 in group A and 5 in group B. In groups C and D, casual BP measurement identified 6 of 38 (15%) patients as hypertensive, whereas 24-hour ABPM again identified a higher number (13 of 38, 34%). CONCLUSIONS: Our findings confirm that 24-hour ABPM is more sensitive than casual BP in detecting abnormal BP in patients at high risk for secondary hypertension.  相似文献   

2.
动态血压监测在儿童肾脏疾病中的临床研究   总被引:1,自引:0,他引:1  
目的 研究儿童肾脏疾病中的动态血压(ABP)的特点.方法 以33例肾脏疾病患儿为研究对象,采用ABPM6100仪进行动态血压测量(ABPM),受试对象均未服用降压药物.以1997年德国1141名健康儿童的ABP值作为正常参考值.结果 夜间高血压发生率高于日间高血压发生率;夜间收缩/舒张压负荷(29.1±34.5)%/(24.9±34.3)%和指数(0.95±0.11)/(0.90±0.18)明显大于日间收缩/舒张压负荷(12.9±23.6)%/(9.3±19.1)%和指数(0.88±0.09)/(0.77±0.12);肾脏疾病患儿夜间收缩/舒张压下降率为(6.6±6.0)%/(8.8±10.2)%,明显低于正常值(13±6)%/(23±9)%;高达24例(72.7%)患儿夜间收缩压和(或)舒张压下降率为"非杓型",即使在正常血压者中也有72.7%的"非杓性"发生率.在33例患儿中随机血压(CBP)升高者5例,均有ABP升高;CBP正常者28例,但其中6例ABP升高.结论 ABPM能发现儿童肾脏疾病中的夜间高血压和血压昼夜节律的异常,为调整用药时机和更全面有效地控制血压提供依据,弥补了传统血压测量的不足;并能发现隐匿性高血压,可以早期发现高血压前期,从而有利于随访和尽早干预.  相似文献   

3.
The objective of the present study was to define the risk factors for hypertension and to analyze the influence of insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) on hypertension in pediatric renal transplant recipients. Twenty-six pediatric renal transplant recipients with stable renal function and treated with the same immunosuppression protocol were included in the study. Their mean age was 12.5 +/- 3.3 yr and mean time after transplantation was 38.5 +/- 39.8 month. Twenty-four hour ambulatory blood pressure monitoring (ABPM) was performed by SpaceLabs (90207) device. The I/D polymorphism of the ACE was determined by PCR and ACE serum level was analyzed by colorimetric method. Hypertension was present in 15 patients (57.7%) by causal blood pressure measurements and 19 patients (73.1%) by ABPM. Twenty-two patients (84.6%) were found to be non-dipper and eight of them had reverse dipping. Only time after transplantation (38 +/- 31 vs. 79 +/-49 month, p = 0.016) and cyclosporin A trough plasma levels (206 +/-78 vs. 119 +/- 83 ng/mL, p = 0.020) influenced the presence of hypertension by multiple logistic regression analysis. The distribution of genotypes were II = 2 (7.7%), ID = 8 (30.8%), DD = 16 (61.5%). There was no effect of ACE gene I/D polymorphism or serum ACE levels on hypertension prevalence and circadian variability of blood pressures. Hypertension was related to the time after transplantation and cyclosporin A levels. The ACE gene I/D polymorphism and serum ACE levels did not influence the blood pressure values or circadian variability of blood pressure among pediatric renal transplant patients.  相似文献   

4.
Autoregulation of cerebral blood flow in the preterm fetal lamb   总被引:6,自引:0,他引:6  
The purpose of the present study was to determine if autoregulation of cerebral blood flow (CBF) is present in the preterm fetal lamb and, if present, to measure the range of mean arterial blood pressure over which autoregulation exists. Thirty-seven measurements of CBF were made in seven preterm fetal lambs (118-122 days gestation) over a mean carotid arterial blood pressure (CBP) range of 18-90 mm Hg. CBF was measured by the radionuclide-labeled microsphere technique. CBP was altered by graduated inflation of balloons placed around the brachiocephalic trunk and the aortic isthmus. To eliminate the effects of reflex changes in heart rate, the carotid sinus and aortic nerve were ablated bilaterally. CBF was linearly related to mean CBP from 18-45 mm Hg, constant over a mean CBP of 45-80 mm Hg, and again linear from 80-90 mm Hg. Resting mean CBP (normotension) was 53.8 +/- 1.9 mm Hg during the control period and 51.7 +/- 0.8 mm Hg during the equilibration periods. This study demonstrates that although autoregulation of CBF is intact in the preterm fetal lamb, the range is narrowed compared to the term lamb and resting mean CBP lies close to the lower limit of autoregulation.  相似文献   

5.
To evaluate the central hemodynamic and regional blood flow changes associated with right ventricular hypertension in the newborn, 13 anesthetized, mechanically ventilated piglets less than 3 d old were acutely instrumented to permit measurements of central vascular pressures, cardiac output, and regional blood flow (radio-labeled microsphere technique). After initial measurements, right ventricular afterload was progressively increased by means of a pulmonary arterial mechanical occluder until right-to-left foramen ovale shunt was observed. An increase in pulmonary arterial pressure from 32 +/- 2 to 55 +/- 3 mm Hg was associated with a decrease in PaO2 from 364 +/- 16 to 88 +/- 9 mm Hg and an increase in the shunt fraction from 13 +/- 1 to 28 +/- 1% (p less than 0.01) during ventilation with oxygen. Right ventricular hypertension induced a significant decrease in systemic arterial pressure from 79 +/- 3 to 63 +/- 4 mm Hg, and left ventricular cardiac output from 156 +/- 10 to 112 +/- 11 mL.min-1.kg-1 (p less than 0.01), likely secondary to a reduction in left ventricular compliance. Oxygen delivery to the brain and heart were unaffected, due to a substantial increase in regional blood flow, but a significant reduction in delivery to the bowel and kidneys were observed. Contrary to what has been reported in the adult, myocardial blood flow to the right ventricle increased during hypertension. Metabolic acidosis was seen in all animals and the changes in serum bicarbonate and whole body oxygen consumption were directly related to the magnitude of decline in systemic O2 delivery.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

6.
Ambulatory blood pressure measurements   总被引:11,自引:0,他引:11  
Ambulatory blood pressure monitoring (ABPM) has emerged as a valuable clinical and research tool in the assessment of pediatric hypertension. Large databases of 24-hour blood pressure monitorings in healthy children are under development for establishing normal reference values analogous to the Task Force data for casual blood pressure. In the clinical setting, pediatric studies using ABPM to evaluate elevated blood pressure have shown that the prevalence of white coat hypertension in children is similar to that reported in adults. Furthermore, 24-hour blood pressure parameters are correlated with hypertensive end-organ injury such as left ventricular hypertrophy. ABPM has allowed detailed assessment of circadian blood pressure patterns that show early subtle abnormalities in some high-risk groups and normal patterns in other groups previously thought to be at high risk. These studies will assist in the practice of evidence-based medicine regarding pediatric hypertension that will improve the long-term care that pediatricians provide to their patients.  相似文献   

7.
The pulmonary vasculature of newborns with persistent pulmonary hypertension is characterized by active vasoconstriction and vascular remodeling. It has been suggested that endothelin-1 (ET-1), a potent vasoconstrictor and growth promoter, may be involved in the pathogenesis of persistent pulmonary hypertension of the newborn. To determine whether treatment with an ET(A) receptor antagonist can reverse pulmonary hypertension in the neonate, 1-d-old piglets were exposed to hypoxia for 3 d to induce pulmonary hypertension and then treated for the remainder of the 14 d with an orally active, nonpeptidic ET(A) antagonist (TBC3711, 22 mg x kg(-1) x d(-1)). At the end of the exposure, Hb, pulmonary artery pressure, right ventricle to left ventricle plus septum weight ratio, percentage wall thickness, ET-1 circulating levels, perfusion pressure, and dilator response to the nitric oxide (NO) donor, SIN-1 (3-morpholinosydnonimine-N-ethylcarbamide) in isolated perfused lungs were determined. Exhaled NO and hemodynamic variables were also examined in an intact anesthetized animal preparation that had undergone the same treatment. By 3 d of exposure to hypoxia, piglets had already developed significant pulmonary hypertension as estimated by their pulmonary artery pressure (24.0 +/- 1.3 mm Hg versus 14.2 +/- 3.4 mm Hg) and percentage wall thickness (26.6 +/- 5.9% versus 18.7 +/- 2.4% for vessels 0-30 microm). Whereas further exposure to hypoxia for 14 d did not enhance the increase in pulmonary artery pressure and percentage wall thickness, it did augment the right ventricle to left ventricle plus septum weight ratio (0.71 +/- 0.09 versus 0.35 +/- 0.01). ET-1 circulating levels were increased only when exposure to hypoxia was prolonged to 14 d (5.1 +/- 2.4 pg/mL versus 1.0 +/- 0.4 pg/mL). Treatment with TBC3711 from d 3 to d 14, once pulmonary hypertensive changes were established and while hypoxic exposure persisted, caused significant reduction in the right ventricle to left ventricle plus septum weight ratio (0.60 +/- 0.06), pulmonary artery pressure (20.0 +/- 4.8 mm Hg), and percentage wall thickness (18.5 +/- 3.3%) and restored the dilator response to the NO donor SIN-1. Prolonged hypoxia markedly reduced exhaled NO concentrations (0.3 +/- 0.6 ppb), although treatment of hypoxic animals with TBC3711 restored the concentration of exhaled NO (4.4 +/- 2.8 ppb) to the level of normoxic controls (4.9 +/- 3.0 ppb). Lastly, treatment with TBC3711 increased ET-1 circulating levels in both the normoxic (5.4 +/- 2.8 pg/mL) and hypoxic (13.0 +/- 6.3 pg/mL) groups. In conclusion, the specific ET(A) receptor antagonist, TBC3711, can significantly ameliorate the morphologic changes encountered in hypoxia-induced pulmonary hypertension in the newborn piglet and may improve the dilator response to NO.  相似文献   

8.
Twenty-four-hour ambulatory blood pressure monitoring (ABPM) has proven to have better reproducibility than office blood pressure (BP) and is increasingly used for the study of hypertension in children and adolescents. The aim of our study was to assess 24-h BP profiles and to compare the results of office BP measurements with ABPM in stable liver transplant recipients transplanted before the age of 18 yr. ABPM was performed in 29 patients (nine males, 20 females), aged 3.9-24.8 yr (median 10.8 yr). The investigation was conducted 1.1-11.5 yr (median 5.1 yr) following transplantation. ABPM confirmed hypertension in one out of three office hypertensive patients. Seven patients (24%), whose office BP recordings were within the normotensive range, were reclassified as hypertensive. Non-dippers (n = 17), arbitrarily defined as patients with less than 10% nocturnal fall in BP, were similarly distributed among patients with ambulatory normotension and ambulatory hypertension (chi(2), p = 0.79). In addition, non-dippers showed a negative correlation between 24-h total urinary albumin excretion and both systolic and diastolic nocturnal decline in BP (Rho = -0.48, p < 0.05 and Rho = -0.86, p < 0.01, respectively). Our study found office BP readings to be poorly representative of 24-h BP profile. Larger studies are needed to confirm our observations as well as to determine whether routine BP measurements in the follow-up of paediatric liver transplant recipients should be based solely on office BP.  相似文献   

9.
Periventricular and intraventricular intracerebral hemorrhages occur frequently in premature newborns and are markers for, or contribute significantly to, neurologic morbidity in survivors. Hemorrhages are hypothesized to result from rapid fluctuations in cerebral perfusion pressure and/or cerebral blood flow. Phenobarbital sodium has been given to premature infants in anticonvulsant dosages in attempts to prevent hemorrhages, but its efficacy in clinical studies has been disputed. In this study, in the 24 to 72-hour-old newborn beagle, an animal model for periventricular and intraventricular intracerebral hemorrhage, phenobarbital sodium was administered to obtain anticonvulsant serum levels prior to phenylephrine-induced hypertensive insult. None of the animals was hypoxic or hypercarbic. Resulting hypertensive systemic mean arterial BPs were 99 +/- 8 mm Hg in the 15 control pups and 93 +/- 15 mm Hg in the 15 phenobarbital sodium-treated pups (not statistically significantly different). The duration of the hypertension was the same in both groups. Phenobarbital caused a significant decrease in mean arterial BP in the treated group just after its administration (P less than .05). Six of the 15 control pups (40%) and one of the 15 treated pups (7%) demonstrated macroscopic and microscopic periventricular and intraventricular hemorrhage (P less than .05, chi 2, Yates correction). Thus, in nonasphyxiated newborn beagles, phenobarbital sodium significantly reduced the incidence of hemorrhage after hypertensive insult.  相似文献   

10.
OBJECTIVES: Evaluation of the efficacy and safety of amlodipine in hypertensive children. STUDY DESIGN: A randomized, double blinded, placebo-controlled, parallel-group, dose-ranging study was conducted at 49 centers in North and South America. The primary end point was the effect of amlodipine on systolic blood pressure (BP); secondary end points included the effect of amlodipine on diastolic BP, the effect of amlodipine as a function of dose and body size, and evaluation of safety. RESULTS: We enrolled 268 hypertensive children (mean age, 12.1 +/- 3.3 years); 84 (31.3%) had primary hypertension, and 177 (66%) were boys. Amlodipine produced significantly greater reductions in systolic BP than placebo; these were -6.9 mm Hg for 2.5 mg daily (P=.045 vs placebo) and -8.7 mm Hg for 5 mg daily (P=.005 vs placebo). The underlying cause of hypertension had no effect on the response to amlodipine. There was a significant dose-response effect of amlodipine on both systolic and diastolic BP beginning at doses > or =0.06 mg/kg per day. Systolic BP < or =95(th) percentile was achieved in 34.6% of subjects with systolic hypertension. Amlodipine was well tolerated, with just 6 children withdrawn from treatment because of drug-related adverse events. CONCLUSIONS: Amlodipine effectively lowers systolic BP in a dose-dependent manner in hypertensive children who require drug treatment.  相似文献   

11.
Ambulatory blood pressure monitoring (ABPM) in adults is proving to be useful. The aim of this study was to determine if ABPM is accurate in the lower blood pressure range encountered in children and, equally important, whether it is acceptable to children. Thirty one children, between the ages of 6 and 18 years, were assessed using an ambulatory blood pressure monitor that uses an auscultatory method. Blood pressure was measured in the contralateral arm with a mercury sphygmomanometer and an oscillometric device at the beginning and end of the study for comparison. Over a blood pressure range of 90-130 mm Hg systolic and 40-80 mm Hg diastolic, a close agreement was found with the sphygmomanometer; the limits of agreement (+/- 2 SD) were 11.6 mm Hg for systolic blood pressure and 13.6 mm Hg for diastolic blood pressure. The bias was less than 1.0 mm Hg. The ambulatory device was worn by all patients for at least 16 hours with an average of 52 recordings per patient. The majority found the device comfortable to wear and were not woken from sleep.  相似文献   

12.
Ambulatory blood pressure monitoring (ABPM) in adults is proving to be useful. The aim of this study was to determine if ABPM is accurate in the lower blood pressure range encountered in children and, equally important, whether it is acceptable to children. Thirty one children, between the ages of 6 and 18 years, were assessed using an ambulatory blood pressure monitor that uses an auscultatory method. Blood pressure was measured in the contralateral arm with a mercury sphygmomanometer and an oscillometric device at the beginning and end of the study for comparison. Over a blood pressure range of 90-130 mm Hg systolic and 40-80 mm Hg diastolic, a close agreement was found with the sphygmomanometer; the limits of agreement (+/- 2 SD) were 11.6 mm Hg for systolic blood pressure and 13.6 mm Hg for diastolic blood pressure. The bias was less than 1.0 mm Hg. The ambulatory device was worn by all patients for at least 16 hours with an average of 52 recordings per patient. The majority found the device comfortable to wear and were not woken from sleep.  相似文献   

13.
When ambulatory blood pressure monitoring (ABPM) is performed in populations with a high risk for secondary hypertension, such as solid organ transplant recipients, hypertension or abnormalities in circadian blood pressure variability are often discovered even in patients with normal office blood pressure (BP). To discuss whether ABPM should be routinely assessed in pediatric solid organ recipients, the available information on pathological findings, association of ABPM abnormalities with outcome parameters, and treatment options is reviewed. ABPM is a useful tool to optimize therapy in the large proportion of transplant recipients with confirmed hypertension. Whether the use of ABPM on a routine basis should be recommended for pediatric transplantation patients without office hypertension remains to be determined.  相似文献   

14.
OBJECTIVE: To determine the factors that contribute to the pathogenesis of isolated systolic hypertension in children. METHODS: School-based measurement was performed of blood pressure (BP), heart rate, weight, and height in 2460 students (49% Hispanic, 31% black, 13% white) 12 to 16 years of age in 8 urban public schools. An independent group of 71 untreated children underwent 24-hour ambulatory BP monitoring (ABPM) to confirm clinic hypertension and assess circadian BP patterns. RESULTS: Hypertension and obesity were found in 17% and 23% of students, respectively. Among hypertensive students, 88% (363/413) had isolated systolic hypertension. Hypertension was more prevalent in obese than nonobese students (33% vs 11%, P <.0001). Obese hypertensive students had higher resting heart rate than nonobese normotensive patients (85.9 vs 79.6 beats/min, P <.001). Among patients who underwent ABPM, isolated systolic hypertension was found in 51% (36/71) by clinic BP and in 62% (18/29) with confirmed hypertension by ABPM. Blood pressure variability during daytime and sleep periods was higher in obese than nonobese patients for systolic BP (P <.01) and diastolic BP (P <.05). CONCLUSIONS: The findings of increased heart rate and BP variability in obese children with isolated systolic hypertension suggest that sympathetic nervous system hyperactivity may contribute to its pathogenesis.  相似文献   

15.
Restriction of maternal protein intake during rat pregnancy produces offspring that are hypertensive in adulthood, but the mechanisms are not well understood. Our purpose was to determine whether this adult hypertension could be programmed during development by suppression of the fetal/newborn renin-angiotensin system (RAS) and a consequent reduction in nephron number. Pregnant rats were fed a normal protein (19%, NP) or low-protein (8.5%, LP) diet throughout gestation. Birth weight was reduced by 13% (p < 0.0005), and the kidney/body weight ratio was reduced in LP pups. Renal renin mRNA levels were significantly reduced in newborn LP pups; renal renin concentration and renin immunostaining were suppressed. Renal tissue angiotensin II levels were also suppressed in newborn LP (0.079 +/- 0.002 ng/mg, LP versus 0.146 +/- 0.016 ng/mg, NP, p < 0.01). Mean arterial pressure in conscious, chronically instrumented adult offspring (21 wk) was higher in LP (135 +/- 1 mm Hg, LP versus 126 +/- 1 mm Hg, NP, p < 0.00007), and GFR normalized to kidney weight was reduced in LP (p < 0.04). The number of glomeruli per kidney was lower in adult LP offspring (21,567 +/- 1,694, LP versus 28,917 +/- 2,342, NP, p < 0.03), and individual glomerular volume was higher (1.81 +/- 0.16 10(6) microm(3), LP versus 1.11 +/- 0.10 10(6) microm(3), NP, p < 0.005); the total volume of all glomeruli per kidney was not significantly different. Thus, perinatal protein restriction in the rat suppresses the newborn intrarenal RAS and leads to a reduced number of glomeruli, glomerular enlargement, and hypertension in the adult.  相似文献   

16.
Multicystic dysplastic kidney (MCDK) is one of the most common congenital renal anomalies. Arterial hypertension is a potential complication of MCDK. Blood pressure (BP) has so far been measured only casually and the frequency of hypertension has been estimated to be between 0%–8%. Ambulatory blood pressure monitoring (ABPM) provides more precise information on BP than the casual BP measurement. The aim of this study was to investigate the BP profile in children with MCDK using ABPM. A group of 25 children (16 girls), with a mean age of 7.8 years (range 3.8–17.7 years) were investigated. ABPM was performed using the oscillometric SpaceLabs 90207 device. Hypertension was defined as mean systolic and/or diastolic BP during the day and/or in the night exceeding 95th percentile for ABPM. Five (20%) children showed hypertension, two of them had combined daytime and night-time hypertension and three had isolated nocturnal hypertension, although daytime BP was between the 90th–95th percentile in two of them. Children with ultrasonographical and/or laboratory signs of contralateral kidney abnormalities showed a higher incidence of hypertension than those without abnormalities (two of four versus 3 of 21). The mean night-time systolic and diastolic BP of children with MCDK was significantly higher than in healthy children (+0.50 and +0.54 SDS, respectively, P=0.012 and 0.03, respectively). Three of the hypertensive children were already nephrectomised. All five hypertensive children showed ultrasonographical and/or laboratory signs of contralateral kidney abnormalities. Hypertensive children had significantly higher microalbuminuria than normotensive children (6.9 ± 3.2 mg/mmol creatinine versus 1.8 ± 0.7, P=0.03). The nocturnal BP fall (dip) was attenuated in five children, only one of whom was hypertensive. Conclusion Arterial hypertension in children with multicystic dysplastic kidney is seen more often if based on ambulatory blood pressure monitoring than on casual blood pressure recordings. The main risk factor for developing hypertension is contralateral kidney damage. Ambulatory blood pressure monitoring should be performed in children with multicystic dysplastic kidney, especially in those with contralateral kidney abnormalities. Received: 20 July 1999 and in revised form: 27 November 1999, 24 March 2000, 3 May 2000 Accepted: 3 May 2000  相似文献   

17.
White coat hypertension in children with elevated casual blood pressure   总被引:10,自引:0,他引:10  
OBJECTIVE: We reviewed our experience using ambulatory blood pressure monitoring (ABPM) in children referred to a hypertension clinic to determine the frequency of pediatric white coat hypertension (WCH). STUDY DESIGN: WCH was defined by 3 different diagnostic criteria: (1) mean 24-hour blood pressure (BP) less than Task Force-defined 95th percentile, (2) mean 24-hour BP less than 95th percentile from pediatric normative ABPM data, and (3) mean 24-hour BP less than ABPM 95th percentile and BP load (percentage of BP readings during 24-hour period exceeding the 95th percentile) less than 25%. RESULTS: Clinic BP values were available in 67 otherwise healthy children who underwent ABPM; 51 had confirmed clinic hypertension by Task Force criteria. WCH frequency in these 51 patients with the stated criteria was 53%, 45%, and 22%, respectively. Elevated BP load was found in 52% (12/23) of patients with normal mean BP. CONCLUSION: These results suggest that many children referred for casual BP elevation have WCH even by strict diagnostic criteria. ABPM may help differentiate WCH from persistent hypertension, thereby avoiding unnecessary diagnostic evaluation and identifying children most likely to benefit from early intervention.  相似文献   

18.
Intrauterine programming of hypertension is associated with evidence of increased renin-angiotensin system (RAS) activity. The current study was undertaken to investigate whether arterial baroreflex and blood pressure variability are altered in a model of in utero programming of hypertension secondary to isocaloric protein deprivation and whether activation of the RAS plays a role in this alteration. Pregnant Wistar rats were fed a normal-protein (18%) or low-protein (9%) diet during gestation, which had no effect on litter size, birth weight, or pup survival. Mean arterial blood pressure (MABP; 126 +/- 3 mm Hg 9% versus 108 +/- 4 mm Hg 18%; p < 0.05) and blood pressure variability were significantly greater in the adult offspring of the 9% protein-fed mothers. Arterial baroreflex control of heart rate, generated by graded i.v. infusion of phenylephrine and nitroprusside, was significantly shifted toward higher pressure; i.v. angiotensin-converting enzyme inhibitor normalized MABP and shifted the arterial baroreflex curve of the 9% offspring toward lower pressure without affecting the 18% offspring. For examining whether brain RAS is also involved in programming of hypertension, angiotensin-converting enzyme inhibitor and losartan (specific AT(1) receptor antagonist) were administered intracerebroventricularly; both significantly reduced MABP of the 9% but not the 18% offspring. Autoradiographic receptor binding studies demonstrated an increase in brain AT(1) expression in the subfornical organ and the vascular organ of the lamina terminalis in the 9% offspring. These data demonstrate a major tonic role of brain and peripheral RAS on hypertension associated with antenatal nutrient deprivation.  相似文献   

19.
Environmental hyperthermia is a hazard to the poikilothermic chick embryo. We studied effects of hyperthermia on mean vitelline arterial blood pressure and mean dorsal aortic blood flow in stage 18, 21, and 24 chick embryos. The pressure was measured with a servo-null micropressure system, and the blood flow was measured with a 20 MHz pulsed Doppler flowmeter. Temperature was monitored with a needle thermoprobe positioned adjacent to the embryo. Data were obtained at 37 degrees C, after warming to 40 degrees C, and then after cooling to 37 degrees C. At stage 21, the pressure increased from 0.96 +/- 0.05 (+/- SE) to 1.04 +/- 0.06 mm Hg on warming and returned from 1.05 +/- 0.04 to 0.87 +/- 0.04 mm Hg on cooling. Pressure measurements during warming and cooling were performed in two separate groups of embryos because of technical problems. The blood flow, studied using different groups of the embryo from the pressure study, also increased from 0.65 +/- 0.06 to 0.75 +/- 0.06 mm3/s on warming and returned to 0.56 +/- 0.05 mm3/s. The heart rate increased from 173 +/- 2 to 211 +/- 3 at 40 degrees C and returned to 170 +/- 3 at 37 degrees C. Stroke volume (flow/heart rate) did not change during the temperature variation. Vascular resistance, the quotient of pressure to blood flow obtained by a ratio analysis, changed from 1.53 +/- 0.33 (median +/- 95% confidence interval) to 1.42 +/- 0.29 mm Hg/mm3/s on warming and changed to 1.60 +/- 0.32 mm Hg/mm3/s on cooling. Similar results were obtained at stages 18 and 24.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

20.
Ambulatory blood pressure monitoring in children and adolescents   总被引:2,自引:0,他引:2  
With recent technological advances, 24-hour ambulatory blood pressure (BP) monitoring (ABPM) has become a useful tool for the evaluation, diagnosis, and management of hypertensive children. It provides a more accurate representation of an individual's BP rather than intermittent casual or office BP measurements. Hence, ABPM is being used more often to assess the BP of children. In this comprehensive review, we provide the reader with the available literature on ABPM, discuss the advantages and limitations of ABPM, and the interpretation of ABPM data. The role of ABPM in various clinical conditions and hypertension research in children is presented.  相似文献   

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