摘要:

Opposed actions for nitric oxide (NO) and angiotensin II (Ang II) in vascular contraction and vascular smooth muscle cell proliferation and apoptosis are well documented. In addition, various experimental approaches have shown that NO negatively modulates the renin–angiotensin system by inhibiting angiotensin-converting enzyme (ACE) activity and down-regulating AT1receptors. On the other hand, Ang II and Ang-(1–7) positively stimulate NO synthesis and release. In this review, we analyse the data suggesting a mutual regulation between the renin–angiotensin and the nitric oxide-generating systems, and we propose a homeostatic interplay between both factors aimed at regulating cardiovascular function.

ISSN:0263-6352    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectivesTo develop a national standard level of blood pressure (BP) for Italian children on the basis of a large sample of the population.DesignWe analyzed data available from 21 Italian studies conducted according to the recommendations of the American Task Force between 1988 and 1994. Percentile curves of systolic and diastolic BP were constructed by fitting a third-order polynomial model of BP on age and height using multiple regression analysis.ParticipantsBP was measured in 11 519 healthy individuals (6258 boys and 5261 girls) aged 5–17 years in various locations throughout Italy. All measurements were performed at school.ResultsPercentile curves (5th, 10th, 25th, 50th, 75th, 90th and 95th) of systolic and diastolic BP are reported by age and by height for males and females.ConclusionsWith respect to the American standards, the levels in Italy for the 90th and 95th percentiles were 3–8 mmHg higher for systolic and diastolic BP in both sexes between 5 and 12 years of age, and 2–3 mmHg higher in older males. With respect to Northern Europe, in the lower ages, levels in Italy were quite similar, although slightly higher, whereas in late adolescence, the Northern European levels were much higher, especially in males, with differences of 4–5 mmHg for the mean values and 8–12 mmHg for the 95th percentile.

ISSN:0263-6352    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveTo study the association between blood pressure and risk of myocardial infarction in elderly subjects.DesignProspective cohort study.SettingThe Rotterdam Study, a Dutch population-based study.Participants6004 men and women aged ≤ 55 years.Main outcome measuresFatal or non-fatal myocardial infarction (n= 190) during a 4-year follow-up.ResultsAfter excluding participants using blood pressure-lowering medication and participants with a history of myocardial infarction, increasing levels of systolic blood pressure (SBP) were associated with increasing risk of first myocardial infarction (Pfor trend < 0.0001). The relative risk (RR) for an SBP of 160 mmHg or higher was 5.7 (95% confidence interval (Cl) 1.9–17.1) compared with an SBP below 120 mmHg. Increasing diastolic blood pressure (DBP) was also associated with increasing risk of first myocardial infarction, with the RR reaching 2.5 (95% Cl 1.4–4.5) in subjects with values of 80–90 mmHg compared with values below 70 mmHg (Pfor trend < 0.05). Analyses in subjects aged 70 years and over showed that the positive associations between SBP and DBP and risk of first myocardial infarction remained at older age.ConclusionThese findings in a relatively healthy cohort of elderly subjects do not provide evidence for a J or U shaped relation between SBP and DBP and risk of first myocardial infarction. They suggest that the risk of first myocardial infarction increases with increasing level of systolic and diastolic blood pressure and that this relationship persists into older age.

ISSN:0263-6352    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveTo investigate 1-year effects of hormone replacement therapy (HRT) on ambulatory blood pressure (ABP) and lipoprotein levels in postmenopausal women with coronary artery disease (CAD).MethodsSixty patients at a mean age (± SD) of 59 ± 7 years were randomized into three groups: conjugated equine oestrogens (CEE) 0.625 mg daily (n= 20), 50 μg 17β-oestradiol transdermally (TTSE) per 24 h (n= 20) or placebo (n= 20) for 18 days, then combined with medroxyprogesterone acetate 5 mg for 10 days. Each cycle of 28 days was repeated for one year.ResultsNight-time systolic ABP had decreased by 9.6% (P= 0.0075) in 15 of 18 women in the CEE group and by 22% in 12 of 13 women (P= 0.0034) in the placebo group after 1 year. In the CEE group, a 4.6% rise in daytime systolic ABP (P< 0.05) and a 4.2% rise in night-time systolic ABP (P< 0.05) appeared from baseline to 6 months in 13 of 18 women. In the CEE group (14 women analysed), high-density lipoprotein levels showed a 15.8% increase (P= 0.0018) in 13 women, low-density lipoprotein levels a 15.2% decrease (P= 0.0129) in 12 women and total cholesterol levels a 7.5% decrease (P= 0.057) in 11 women after 1 year. Triglyceride levels showed no changes. In the TTSE group and in the placebo group, with 12 and 13 women analysed respectively, no significant changes appeared.ConclusionsOne year of HRT in patients with CAD does not influence ABP. Oral HRT induces beneficial effects on lipoprotein levels.

ISSN:0263-6352    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveA new derivative of 24 h ambulatory blood pressure monitoring (ABPM) is introduced and its association with left ventricular mass index (LVMI) in essential hypertension is examined.Patient populationOne hundred and fifty-three previously untreated essential hypertension patients.MethodsPatients underwent casual blood pressure (BP) readings, 24 h ABPM and left ventricular echocardiographic assessment. The following 24 h awake and sleep ABP variables were calculated: mean systolic and diastolic BP, systolic and diastolic BP loads (percentage of systolic readings > 140/120 mmHg (day/night) and diastolic readings > 90/80 mmHg (day/night)), standard deviation of systolic and diastolic ABP and nocturnal fall of systolic BP, as well as the integrated areas under the ABP curve. The area under the BP curve divided in horizontal slices was accurately modelled by a sigmoid curve. The parameters controlling the shape of the curve and in particular that regarding its ‘slope’ is hereafter called the ‘pressure-time index’.Results‘Systolic pressure-time index 24 h’ (SPTI24) is related to left ventricular mass index (multivariate analysis,P= 0.008). Using either partial correlation coefficients or a multivariate analysis, SPTI24is related to left ventricular mass index, independently of age, casual blood pressure, mean systolic and diastolic ABP, systolic and diastolic BP loads, BP variability (standard deviation (SD), nocturnal fall of systolic BP) and integrated area under the curve (multivariate analysis,P= 0.004).ConclusionsIn essential hypertension, the SPTI24is related to LVMI independently of age, casual blood pressure, integrated area under the curve or any other derivative of 24 h ABPM, and might be used to assess the extent of hypertensive load.

ISSN:0263-6352    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveThere is limited information on the mechanisms mediating the deleterious effects of passive smoke exposure. Cross-sectional studies indicate that nonsmokers exposed chronically to passive smoke have impaired endothelium mediated vasodilation. We tested the hypothesis that acute exposure to sidestream (passive) smoke impairs endothelium-dependent vasodilation in healthy nonsmokers.Methods and resultsWe studied 12 healthy nonsmokers (aged 27 ± 5 years, nine men and three women). We obtained measurements of blood pressure, heart rate, and bilateral forearm blood flow (FBF). Each individual was studied twice, following a randomized, placebo-controlled design. The effects of passive smoke were studied on one day and the effects of vehicle (room air) on a separate day. Acetylcholine (ACh) and sodium nitroprusside (SNP) were infused into the left brachial artery before and after 15 min of exposure to either passive smoke (carbon monoxide concentration between 20 and 40 p.p.m.) or vehicle (room air). The order of ACh and SNP, and smoke or vehicle, was randomized between individuals. Smoke exposure increased carboxyhemoglobin from 0.5 ± 0.1% to 0.8 ± 0.1% (P= 0.002). Neither passive smoke nor vehicle changed baseline measurements of heart rate, blood pressure and forearm vascular resistance (FVR). The vasodilatory responses to ACh and SNP were very similar, both before and after exposure to passive smoke and before and after vehicle.ConclusionOur data demonstrate that acute exposure to passive smoke does not alter either endotheliumdependent or independent vasodilatory responses in healthy nonsmoking individuals. Hence, impaired endothelial vasodilatory responses in nonsmokers chronically exposed to passive smoke most likely reflect chronic functional and/or structural changes in responses to cigarette smoke, rather than the acute effects of cigarette smoke toxicity on endothelial function.

ISSN:0263-6352    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveWe have previously shown that conduit arteries of normotensive (WKY) and hypertensive (SHR) Japanese rats differ from normotensive (LN) and hypertensive (LH) Lyon rats in terms of lower aortic thickness and higher collagen III content, whereas differences in vasoactive properties are unknown.MethodsAortic rings with (E+) and without (E−) endothelium were studied under resting and noradrenaline-stimulated conditions in the presence ofNω-nitro-L-arginine (L-NNA) alone or in association with indomethacin, bosentan and/or BQ123.ResultsUnder resting conditions, aortas of normotensive and hypertensive Japanese rats differed from Lyon rats by higher developed tension in the presence of L-NNA and endothelium. In the absence of endothelium, normotensives differed from hypertensives in terms of stronger developed tensions in the presence of L-NNA in the two strains. Addition of indomethacin to L-NNA induced relaxation in E+ SHR and E− WKY and contraction in E− LH. By contrast, tensions were unchanged after addition of bosentan and BQ123. Under stimulated conditions, tensions were equally increased by L-NNA in E+ and unchanged in E− both in Japanese and Lyon rats whether they were normotensive or hypertensive, and indomethacin (but not bosentan) elicited higher response in Lyon than in Japanese rats in E+ and E− aorta.ConclusionUnder NO synthase inhibition, the vasoactive properties of Japanese and Lyon aorta differ in the presence of a cyclo-oxygenase blocker but not endothelin blockers. These results indicate that the aorta vasorelaxant tone is associated to prostanoid regulation in Lyon but not in Japanese rats. This observation appears dependent on the genetic and/or environmental background linked to the origin and not the presence of hypertension.

ISSN:0263-6352    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveThe purpose of this study was to test the hypothesis that a different incidence of apoptosis occurs in the mesenteric arteries of the spontaneously hypertensive rat (SHR) compared with its normotensive control the Wistar-Kyoto rat (WKY) at 1–2 weeks of age.DesignWe examined the incidence of apoptotic cells in the blood vessel wall of muscular arteries from the SHR and WKY at 1–2 weeks of age using two techniques of apoptosis measurement, DNA laddering and 3′-OH end labelling. We also measured the volume of the blood vessel wall components and lumen sizes with the confocal microscope to determine whether a differential incidence of apoptosis occurred between the two rat strains.MethodsWe used phenol/chloroform extraction to isolate genomic DNA and assess DNA fragmentation, with gel electrophoresis to determine DNA laddering, and 3′-OH end labelling, where the enzyme terminal deoxynucleotidyl transferase catalyses the addition of fluoresceinconjugated nucleotides to the cut ends of DNA, to detectin situDNA fragmentation. The volume per unit length of the blood vessel structural components was measured by optical sectioning with the confocal microscope.ResultsWe found that the SHR had a significantly decreased incidence of cellular apoptosis over WKY. This was true for both the electrophoretic method where SHR had significantly less fragmented DNA (molecular size < 600 bp) than WKY (P= 0.01), and for the microscopic method where SHR had fewer labelled cells in both the adventitia (P= 0.01) and the media (P= 0.0001) layers of large mesenteric arteries. The volumes of the adventitia, media and lumen in the large mesenteric arteries were similar between the two strains at this age.ConclusionThese findings suggest that a differential incidence of cellular apoptosis at the age of 1–2 weeks may be responsible for the larger media volume found in older SHR and thus contributes to the development of hypertension in these animals.

ISSN:0263-6352    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveTo evaluate effects of eicosapentaenoic acid (EPA), an n–3 polyunsaturated fatty acid, on the exaggerated growth of vascular smooth muscle cells (VSMC) from spontaneously hypertensive rats (SHR).DesignCultured VSMC were prepared by an explant method from thoracic aortas in 8-week-old male Wistar–Kyoto (WKY)/Izumo rats and SHR/Izumo. Effects of EPA on basal DNA synthesis, expression of growth factors and cyclin-dependent kinase 2 (cdk2) activity were examined in VSMC from WKY rats and SHR.MethodsThe cell cycles were synchronized with serum deprivation, then DNA synthesis in VSMC was measured by [3H]-thymidine incorporation. Fatty acid composition of the phospholipid fraction in VSMC was measured by gas chromatography. Expression of platelet-derived growth factor (PDGF) A-chain, transforming growth factor (TGF)- β1 and basic fibroblast growth factor (bFGF) mRNAs was evaluated by reverse-transcription and polymerase chain reaction analysis. Cdk2 activity was determined by autoradiography after polyacrylamide gel electrophoresis of VSMC extracts that had been immunoprecipitated with anti-cdk2 antibody and protein A sepharose, and then incubated with32P-ATP and histone H1.ResultsHigh concentrations (40 and 80 μmol/l) of EPA significantly inhibited basal DNA synthesis in VSMC from both rat strains. Low dose (20 μmol/l) of EPA significantly inhibited basal DNA synthesis in VSMC from SHR, whereas the same dose of EPA stimulated DNA synthesis in VSMC from WKY rats. In analysis of fatty acid composition, low dose of EPA was considerably incorporated in VSMC. Low dose of EPA significantly inhibited angiotensin II- and phorbol ester milisterol-stimulated DNA synthesis in VSMC from both rat strains, whereas EPA did not affect PDGF-AA-stimulated DNA synthesis in VSMC from either rat strain. Low dose of other polyunsaturated fatty acids such as docosahexaenoic acid, arachidonic acid and linoleic acid did not significantly affect basal DNA synthesis in VSMC from either strain. Low dose of EPA significantly inhibited expression of TGF-β1 mRNA in VSMC from SHR, whereas EPA did not affect expression of PDGF A-chain and bFGF mRNAs in VSMC from SHR. Cdk2 activity in VSMC from SHR was higher than that from WKY rats. Low dose of EPA inhibited cdk2 activity in VSMC from SHR, whereas it stimulated the activity in VSMC from WKY rats.ConclusionLow dose of EPA exerted specific inhibition of the exaggerated growth of VSMC from SHR through the suppression of TGF-β.

ISSN:0263-6352    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveEndothelial nitric oxide exerts important effects on the regulation of vascular tone and structure. Variants of the endothelial nitric oxide synthase gene (eNOS) have been associated with hypertension and myocardial infarction, although some reports have shown negative linkage with hypertension. To examine whether the region encoding theeNOSgene is linked with physiological blood pressure variation, we undertook a linkage analysis of this region in the general population.DesignIn healthy volunteer families, we used two independent quantitative linkage analyses to examine the relationship between genotypes and phenotypes, with both parametric and non-parametric and single-locus and multi-point methods.MethodsWe selected 260 families comprising mother and father (aged 40–70 years) and two natural offspring (aged 18–30 years) from the Victorian Family Heart Study. After standardized measurement of clinical data and extraction of DNA, all family members were genotyped at five microsatellite loci including the CA repeat in theeNOSgene by a PCR method. The quantitative linkage analyses were conducted according to two different analysis programs, the Genetic Analysis System (GAS) and the MAPMAKER/SIBS.ResultsWith both linkage analyses, we found no linkage between any of the loci on chromosome 7q35–36 and the phenotypes systolic and diastolic blood pressure, mean arterial pressure, pulse pressure, pulse rate, weight, height and body mass index.ConclusionBased on these results, we conclude that in this population theeNOSgene is not linked to the physiological variation of blood pressure and other related phenotypes.

ISSN:0263-6352    

出版商:OVID    

年代:1999

数据来源: OVID