ISSN:0263-6352    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:0263-6352    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo assess comparative changes in systolic and diastolic blood pressure and incidence of high blood pressure over 4 years, and factors related to these changes, in northern and southern, urban and rural adults in the People's Republic of China.SettingThis is a prospective study of populations surveyed by standardized methods in 1983-1984 and 1987-1988 in north China, Beijing area steel mill workers and farmers, and south China, Guangzhou area shipyard workers and farmers.SubjectsThe subjects were 8805 men and women aged 35-54 years at baseline (1983-1984), of whom 7338 were non-hypertensive (systolic blood pressure <140, diastolic blood pressure <90mmHg, not being administered antihypertensive drugs).Main outcome measuresThe main outcome measures were 4-year changes in systolic and diastolic blood pressures and the 4-year incidence of high blood pressure in persons not hypertensive at baseline.ResultsAt baseline, the average systolic and diastolic blood pressures were higher for Beijing than for Guangzhou cohorts. At resurvey the average systolic blood pressure had increased for seven of eight sex-city-setting cohorts (all but Guangzhou urban men). The Beijing urban cohorts had the greatest increases (men 6.2 mmHg, women 4.9 mmHg, slopes of 1.6 and 1.2 mmHg/year). The incidence of high blood pressure was higher for Beijing than for Guangzhou cohorts in all four comparisons (men and women, urban and rural). Beijing men, urban and rural, had the highest incidence rates (about 21%). In multiple logistic analyses by sex, variables significantly related to 4-year high blood pressure incidence were city, baseline systolic blood pressure and body mass index, change in weight, and, for men, baseline alcohol use and heart rate.ConclusionModifiable lifestyle traits, previously shown to be related to blood pressure and high blood pressure in cross-sectional studies, also relate to the incidence of hypertension.

ISSN:0263-6352    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo assess the impact of the use of different definitions on epidemiological estimates of hypertension.MethodThe four most commonly accepted definitions of hypertension were applied to the 2353 subjects of a hypertension population prevalence survey in Québec.ResultsDepending on the definition used, the estimated prevalences of hypertension ranged from 9.6 to 19.9%, from 9.3 to 22.5% for men and from 9.9 to 17.4% for women. Successful control ranged from 15.5 to 68.1%. Regardless of the definition employed, lack of case detection was the main barrier to hypertension control, from 73.2 to 77.1% for men and from 34.6 to 62.0% for women. Lack of appropriate treatment or compliance, or both, was a more important barrier to blood pressure control for women than for men.ConclusionThis study shows that the choice of a definition has an important impact on clinically and epidemiologically relevant hypertension estimates for impending clinical and public health decisions.

ISSN:0263-6352    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

BackgroundDysfunctional dopamine neurotransmission and defective D1Areceptor-G protein coupling exist in renal proximal tubules (RPT) of the spontaneously hypertensive rat (SHR).ObjectiveTo determine whether differential expression G proteins contributes to these anomalous phenomena.MethodsWe examined the expression levels of the α-subunits of G proteins, in RPT of SHR and the normotensive Wistar-Kyoto (WKY) rat, as well as in striatal membranes, where dopamine functions and receptor-G protein coupling are known to be normal.ResultsIn general, rat striatal membranes displayed overall higher expression levels of the different α-subunits, relative to those of RPT membranes. Moreover, no significant differences were observed between G protein levels in rat striata in SHR and WKY rats. However, in RPT, both subunits of Gsα were equally expressed in SHR and WKY rats. Gi1α was expressed in RPT of SHR and WKY rats the same levels, but neither Goα nor Gzα was detected these membranes; higher (50%) expression levels of Gi2α were found in SHR. The largest difference in α-subunit expression levels between SHR and WKY RPT was observed for Gi3α. This protein was present in SHR RPT at levels 4.8-fold higher than those in WKY rat RPT. The only α-subunit which was slightly depressed (by 20%) in SHR was Gqα.ConclusionThe overexpression of Gi2α and Gi3α in SHR RPT may be of importance in the genesis of hypertension in this animal.

ISSN:0263-6352    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

BackgroundNon-modulating hypertensives are a subset of sodium-sensitive hypertensives characterized by a failure to modulate renal, vascular and adrenal glomerulosa responsivenesses to angiotensin II appropriately.ObjectiveTo investigate the plasma renin activity (PRA) and urinary kallikrein-like activity (Ku) under different sodium conditions in essential hypertensive patients and in the modulating and non-modulating subsets of hypertensives. Additionally, in these groups of patients, the effects on blood pressure of a sustained Na+restriction were evaluated.MethodsFifteen normotensives (10 men, aged 29 ± 5 years) and 54 untreated hypertensives (30 men, aged 34 ± years) were each administered subsequently three different diets containing 240, 140 and 50 mmol/day Na+, each diet for 10 days. At the end of each period, the PRA, Ku, 24 h urinary volume and urinary Na+excretion were measured. Afterwards, the essential hypertensives were classified as 29 modulating essential hypertensives (MHT, 20 men, aged 32 ± 7 years) and 25 non-modulating essential hypertensives (NMHT, 10 men, aged 36 ± 8 years). Non-modulating ones were identified as individuals who failed to increase their effective renal plasma flow and to decrease their filtration fraction by at least 30% from baseline values, 10 days after changing from a low (10 mmol/day) to a high (260 mmol/day) Na+intake. Blood pressure was measured with a Dinamap 8100 Critikon®device. Both PRA and Kuwere measured during normal Na+intake by standard methods. Patients were administered a low-Na+diet (10-50 mmol/day) for 12 months.ResultsIn essential hypertensives, Kuwas lower under the three Na+diets than it was in normotensives (P<0.01) whereas the PRA was higher in hypertensives only during the low Na+intake (P<0.01). The non-modulating patients showed significantly higher PRA levels (4.0 ± 0.8 ng ml h, P<0.05) than did modulating ones (2.6 ± 1.0 ng ml h) or normotensives (2.3 ± 1.0 ng ml h). Conversely, non-modulating hypertensives had lower Ku(4.1 ± 1.0 IU/24h, P<0.025) than did modulating ones (6.2 ±1.0 IU/24h) or normotensives (7.8 ± 2.0 IU/24 h). Blood pressure was significantly reduced during low Na+intake only in normotensives (month 6: 143±4/94 ± 2 mmHg; month 12: 139 ± 5/89 ± 3 mmHg) compared with baseline values (169 ± 4/102 ± 6 mmHg, P<0.025).ConclusionsIt was shown that, in non-modulating hypertensives, in addition to an increased PRA, a reduced kallikrein-like activity coexists and seems to be associated with the impaired Na+handling. Moreover, in these untreated patients the Na+restriction was able to exert an antihypertensive effect even for long periods.

ISSN:0263-6352    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo investigate differences between store-dependent Ca2+in African American and white men.MethodThapsigargin, a potent and specific inhibitor of the sarco(endo)plasmic reticulum Ca2+-ATPase, was used as a probe to elicit store-dependent Ca2+fluxes. Treatment with this agent caused a rise in the cytosolic free Ca2+due to the egress of Ca2+from thapsigargin-sensitive Ca2+stores and the acceleration of external Ca2+influx through storedependent Ca2+channels.DesignLymphocytes were obtained from 22 African Americans and 23 whites. These cells were subjected to thapsigargin treatment and changes in the cellular Ca2+profiles were monitored.ResultsBoth in Ca2+-free and in Ca2+-containing media the increases in cytosolic free Ca2+concentrations after thapsigargin treatment were greater in lymphocytes from African Americans than they were in those from whites. The greater levels of cytosolic Ca2+concentration were coupled with higher rates of Ca2+extrusion in thapsigargintreated lymphocytes from African Americans.ConclusionsThese findings suggest that store-dependent Ca2+fluxes are greater in lymphocytes from African Americans than they are in those from whites. This phenomenon increases the Ca2+turnover rate and might augment the sensitivity to agonists acting through Ca2+signaling systems, thereby predisposing African Americans to essential hypertension.

ISSN:0263-6352    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo investigate the mechanisms involved in the endothelial stimulation of the vascular smooth muscle cell Na/K pump and their possible alteration by hypertension.MethodsThe Na/K pump activity of vascular smooth muscle cells (VSMC) from normotensive Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR) was studied using the radioactive analogue of K+86Rb+. Conditioned medium of bovine endothelial aortic cells was used to investigate the endothelial modulation of VSMC Na/K pump activity.ResultsConditioned medium enhanced VSMC Na/K pump activity (ouabain-sensitive86Rb+uptake), this effect being higher in SHR cells. This stimulatory effect was neither modified in Na+-loaded cells from both rat strains nor inhibited by the Na/H exchange blocker amiloride. Permeable analogues of cyclic adenosine and guanosine monophosphates did not modify the baseline VSMC Na/K pump activity of WKY rats and SHR, and subsequently the guanylate cyclase inhibitor methylene blue did not alter the conditioned medium-induced stimulation of the pump. However, the Ca2+-channel inhibitor nifedipine reduced the Na/K pump stimulation by conditioned medium, this decrease being higher in WKY rat than in SHR VSMC. Moreover, treatment with phorbol 12,13-dibutyrate for 24 h or with the protein kinase C inhibitor staurosporine for 15 min reduced the conditioned medium-induced Na/K pump activation in both VSMC cultures.ConclusionsNa/K pump stimulation by conditioned medium of endothelial cells is mediated mainly via activation of protein kinase C in VSMC from either WKY or SHR VSMC. However, SHR VSMC show some alterations in their intracellular signalling pathways.

ISSN:0263-6352    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

BackgroundAlthough the antihypertensive actions of different angiotensin converting enzyme (ACE) inhibitors are comparable, they may affect central nervous activity, mood and well-being differently. Thus, central nervous actions of ACE inhibitors may represent an essential factor determining compliance with antihypertensive therapy.ObjectiveTo compare central nervous effects of the biochemically different ACE inhibitors fosinopril and enalapril in healthy men.MethodsIn a double-blind cross-over study, auditory event-related brain potentials and heart rate variability were assessed 6 h after oral intake of placebo, enalapril (10 mg) and fosinopril (20 mg) with the doses being equipotent with regard to systemic ACE inhibition. Plasma concentrations of noradrenaline, adrenaline, vasopressin and cortisol were determined 3 and 6 h after drug intake. Central nervous effects mediated via direct systemic hypotensive actions were avoided (although not completely ruled out) by including only subjects (n=14) who displayed no substantial drop in blood pressure following intake of the ACE inhibitors.ResultsEnalapril, but not fosinopril, enhanced the N1 component and the N1-P2 amplitude of the event-related brain potential (P<0.05). In addition, enalapril enhanced plasma noradrenaline concentrations (P<0.05). A similar effect of fosinopril failed to reach significance. There was no clearcut effect of ACE inhibition on heart rate variability, and also plasma concentrations of adrenaline, vasopressin and cortisol remained unaffected.ConclusionThe results suggest an enhancing effect of enalapril on mechanisms regulating stimulus-induced cortical arousal and central nervous sympathetic outflow. The effects diverging between enalapril and fosinopril indicate that access to human brain functions differs among the various types of ACE inhibitors.

ISSN:0263-6352    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveIt has been shown that nitric oxide (NO) plays an important role in the central control of arterial pressure and sympathetic nerve activity. The aim of this study was to determine whether NO can regulate sympathetic nerve activity by an action on pressor neurons within the rostral part of the ventrolateral medulla (VLM).Design and methodsExperiments were performed on anaesthetized rabbits with denervated arterial and cardiopulmonary baroreceptors. The mean arterial pressure (MAP), heart rate and renal sympathetic nerve activity were measured. Microinjections of the NO donors sodium nitroprusside (SNP, 4-50 nmol) and S-nitroso-glutathione (10 nmol), the NO precursor L-arginine (50 nmol) and the NO synthase inhibitor Nw-nitro-L-arginine methyl ester (LNAME, 50 nmol), were made into the functionally identified pressor region in the rostral VLM. The effects of SNP were also determined before and after injection of 5 nmol methylene blue into the same area. In control experiments, injections of D-arginine (50 nmol) and D-NAME (50 nmol), which are the inactive isomers of L-arginine and L-NAME, respectively, were also made into the functionally identified pressor region in the rostral VLM.ResultsMicroinjections of SNP into the rostral VLM pressor region produced a dose-dependent increase in mean arterial pressure and renal sympathetic nerve activity. At the highest dose of 50 nmol, the increase in MAP was 26 ± 5 mmHg (P<0.001) and the sympathetic nerve activity was 53 ± 5% (P<0.001). These effects were abolished following methylene blue injection into the same region. Injection of 10 nmol S-nitroso-glutathion also produced increases in MAP (15 ± 2 mmHg,P<0.001) and in renal sympathetic nerve activity (28 ± 2%,P<0.001). Microinjections of L- or D-arginine resulted in very small depressor responses, but had no significant effect on renal sympathetic nerve activity. Microinjections of L-NAME, but not of D-NAME, caused significant decreases in MAP (19 ± 1 mmHg,P<0.001) and in sympathetic nerve activity (30 ± 3%,P<0.001).ConclusionsThe results indicate that, in the anaesthetized rabbit with denervated baroreceptors, NO has a pressor and sympathoexcitatory action in the rostral VLM, which is mediated by a cyclic GMP-dependent mechanism. Second, endogenous NO may modulate sympathetic activity tonically, by a direct or indirect action on sympathoexcitatory neurons within the rostral VLM.

ISSN:0263-6352    

出版商:OVID    

年代:1996

数据来源: OVID