摘要:

Background:Initiation Sanitaire Informatisée et Scénarisée (ISIS), a French computer-assisted hypertension and cardiovascular risk education program, was developed on a Macintosh computer to provide patients at cardiovascular risk with a modern interactive educational tool combining rigorously scientific information with the aesthetic attractiveness of multimedia communication.Method:Tb test the impact of this tool on patient health information retention, 158 hypertensives hospitalized for initial work-up (day in hospital) or therapeutic adjustments (3 days) were randomized into control (n=79) and ISIS (n=79) groups. Both groups received cardiovascular education via standard means: by physicians, nurses or dieticians and by pamphlets. In addition, ISIS patients underwent a 30–60-min session on the computer with the ISIS program. Cardiovascular knowledge was tested by the same investigator administering a standardized 28-item questionnaire before and 2 months after education. Retesting was by telephone. At the time of first assessment, all patients were aware that they would be retested. A total of 138 completed questionnaires (69 from each group) was analysed.Results:Overall mean cardiovascular knowledge score before education (143±4.2; range, 4–25) improved significantly after education (3.7±3.5,P=0.0001). This improvement was greater in the ISIS than in the control group (3.813.6 versus 2.4 ±3.2, respectively,P=0.02). In hypertensives with an initial score −16, improvements were 4.5 ±3.6 (n=44) and 2.9 ±3.0 (n=45) in the ISIS and control groups respectively (P<0.01). In hypertensives with known disease duration >6 months, improvements were 3.8±3.5 (n=37) and 1.8±3.0 (n=50) in the ISIS and control groups respectively (P<0.01).Conclusion:These results confirm the potential of computer-assisted education in hypertensives from a specialized centre.

ISSN:0263-6352    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

ObjectiveTo study modifications in blood pressure and its short-term variability in hypertensive patients undergoing a psychological stress test.Design and methods:Forty-nine hypertensive patients [27 women and 22 men; age, 46±9 years; systolic/diastolic blood pressure (SBP/DBP), 164 ±10/97±6 mmHg after a 15-day placebo run-in period) were studied. We used the original version of the Stroop Woid Color Conflict Test (SWCCT) to induce mental stress. Haemodynamk parameters (SBP, DBP, mean blood pressure and heart rate) were measured continuously using a non-invasive method (Finapres) with data acquisition every 0.5 s, allowing spectral analysis of SBP variability at rest, during and afterSWCCT (Fast Fourier Transform algorithm on 256-point time series Anapres 1.2).Results:All haemodynamic parameters (Table 1) increased during the stress test (P=0.001). The mean and variability of SBP standard deviation increased during SWCCT (P=0.001 andP=0.003, respectively). Two minutes after the test, SBP returned to the rest level, whereas the overall variability of SBP remained elevated (P=0.007). On spectral analysis the total area under the curve and the medium-frequency component (66–128 mHz) increased during and after SWCCT (P=0.001).Conclusion:Short-term variability of SBP is increased in hypertensives undergoing SWCCT. This stress test appeared to induce sustained orthosympathetic stimulation, as suggested by the increased medium-frequency component (Mayer waves).

ISSN:0263-6352    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

ObjectiveTo estimate the degree of reproducibility of blood pressure variability between two clinic visits.Methods:We recruited 15 untreated people (six hypertensives, nine normotensives) from an outpatient clinic. They had undergone at least one blood pressure measurement by the same investigator (A.G.). The participants underwent 5-min blood pressure monitoring (Finapres 2300; Ohmeda, Trappes, France) while standing and after a rest in a supine position, at 10.00 am and at 23±C in a quiet room. Measurements were repeated after 7 days. A Fast Fourier Transform algorithm was used for analysis.ResultsThere was no order effect, with no difference between visits 1 and 2. Coefficients of variation for systolic blood pressure, diastolic blood pressure and heart rate were 9, 6 and 12%. High coefficients of variation (20%) were observed for the overall variability (total power) and the low frequency (Mayer wave) component of blood pressure. However, the normalized low frequency (low frequency/total area) exhibited an acceptable coefficient of variation of 15%.Conclusion:The blood pressure variability differences observed between visits might reflect an intra-person effect. This should be considered when assessing blood pressure variability and designing drug trials.

ISSN:0263-6352    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Introduction:Recent experiments demonstrated increased isobaric arterial compliance and distensibility in hypertensive patients, which could be explained by a decrease in arterial wall stress, when assessed at constant pressure. We investigated the effect of hypertension on the mechanical properties of the carotid arterial wall, and especially wall stress, assessedin vivoin spontaneously hypertensive rats (SHR).Methods:Right carotid artery internal diameter and wall thickness were continuously monitored in eight 30-week-old anesthetized SHR and seven normotensive Wistar-Kyoto (WKY) rat controls, using a high-resolution (1 μm) transcutaneous A-mode echo-tracking system (Nius 2; Asulab, Lausanne, Switzerland) coupled to a measurement of left carotid arterial pressure (micro-manometer).Results:Mean arterial pressure was 123±6 mmHg in WKY rats and 202±2 mmHg in SHR (P<0.01). Mechanical parameten were calculated at mean pressure from internal diameter and wall thickness pressure curves. There was no difference between the groups in internal diameter (1.129 and 1.200 mm for WKY rats and SHR respectively, NS) and midwall stress (10.5±12 and 10.5±0.7 106dyn/cm2for WKY rats and SHR respectively, NS); wall thickness was increased in SHR (105±8 and 191±16 μm for WKY rats and SHR respectively,P<0.01). Incremental modulus (wall rigidity) was increased in SHR (0.86±0.09 and 1.96±0.25 107dyn/cm2for WKY rats and SHR respectively,P<0.01), whereas disteraibility (1.77±0.16 and 0.54±0.06 10-3/mmHg,P<0.01) and compliance (1.84±0.30 and 0.61±0.07 10-3mm2/mmHg,P<0.01) were decreased.Conclusions:Thus (1) in SHR, mid-wall stress is maintained at a level similar to mat of WKY rats, confirming previousin vitrodata; (2) this maintained stress is most likely the consequence of the increased arterial wall thickness; (3) in contrast to the results obtained at constant pressure, at identical mid-wall stress, the increased modulus explains the decreased extensibility and compliance and reflects the altered intrinsic properties of the carotid arterial wall in SHR.

ISSN:0263-6352    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Introduction:The sympathetic nervous system has been postulated as a factor implicated in the development of cardiac hypertrophy in several experimental models. The present study was designed to characterize the activity and sensitivity of the heart adenyl cyclase pathway in a rat model of cardiac hypertrophy induced by left coronary artery ligation.Methods and results:Three weeks after left coronary occlusion (INf), eight rats developed hypertrophy of the right ventricle compared with six sham operated (CTL) rats [right ventricle weight/body weight ratio (mean±SEM): 0.77±0.09 versus 051±0.03mg/g,P<0.05]. Mean arterial blood pressure and heart rate were similar in both groups. Plasma noradrenaline levels were slightly elevated in the INF group (196.8±8.5 versus 1503±12.6 pg/ml,P<0.05). Total beta-adrenergic receptor density was similar in the left and right ventricles of INF and CTL rats. Basal cyclic AMP production and that induced with isoproterenol (10-9-10-3), Gpp(NH)p (10-9-10-3) and forskolin (10-9-10-4) (pmol/mg per min) were evaluated in ventricular membrane preparations of left and right ventricles in both groups (Table 1). The signal transduction function was inferred from studies of the maximal rate of conversion of ATP to cyclic AMP (Vmax, pmol/mg per min).>Conclusions:The results indicate a lack of desensitization of the beta receptors despite an increase in sympathetic tone. They also suggest an increased activity of Gs proteins and/or of adenyl cyclase. Therefore, a sympathetic hyperactivity coupled to a hyper-sensitivity of the adenyl cyclase signalling pathway seems to develop in hearts subjected to left coronary occlusion. These alterations could affect the development of cardiac hypertrophy in this rat model.

ISSN:0263-6352    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Introduction:The administration of recombinant erythropoietin (rHuEpo) to anaemic chronic renal failure patients may be associated with an increase in blood pressure, possibly by direct effects on peripheral blood vessels. In the present study, experiments were designed to explore the hypothesis that rHuEpo could enhance vascular resistance by a mitogenic effect on vascular smooth muscle cells (VSMQ, and mat pre-existing hypertension might be a predisposing condition.Methods:Cultured VSMC from the thoracic aortae of spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats were studied for DNA synthesis, phospholipase C activity, and cell growth-related protooncogene expression in the presence of rHuEpo. Results: In cells from both strains, rHuEpo dose-dependently increased DNA syndiesis and stimulated phospholipase C activity, as indicated by3H-thymidine incorporation and3H-inositol phosphate formation, respectively (median effective concentration ± 4 U/ml). Exposure of VSMC to rHuEpo for various times gradually increased the levels ofc-mycand JunB and transiendy inducedc-fosexpression, as determined by Northern analysis. rHuEpo-induced DNA synthesis was markedly enhanced in VSMC from SHR compared with those from WKY rats. In contrast, rHuEpo-induced phospholipase C activity and proto-oncogene expression was similar in the two strains.Conclusions:Taken together, these results suggest that rHuEpo may function as a VSMC growth-promoting factor through activation of the phospholipase C cascade and modulation of protooncogene expression. It could thereby contribute to vascular hypertrophy and arterial hypertension.

ISSN:0263-6352    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Introduction:Deuterium oxide (D2O) produced an endothelium-dependent relaxation in mesenteric arterial beds of normotensive rats [1]. The present study was designed to evaluate the effect of chronic treatment with an angiotensin II receptor antagonist, losartan, on the functional state of the vascular endothelium in spontaneously hypertensive rats (SHR), using D2O as a releaser of nitric oxide (NO).Methods:The vascular reactivity was studied on perfused mesen-teric beds from 3-month-old SHR treated or not for 12 days with losaran (n =6–8 per group; 5 mg/kg per day, with osmotic pump) and five normotensive 3-month-old Wistar-Kyoto (WKY) rats. Systolic arterial pressure (SAP, mmHg) was recorded in awake rats. Changes inin vitroperfusion pressure (ΔP, mmHg) were measured before and after the addition of D2O (50% vol/vol) at the plateau of contractions induced by an alpha1-adrenergic agonist, phenylephrine (PHE, 0.1–1.0 μmol/l). This protocol was realized with the endothelium, in the presence or absence ofNG-nitro-L-arginine methyl ester (L-NAME, 100 μmol/l), a NO synthase inhibitor (Table 1).Results:In WKY rats, D2O attenuated the pressor response to PHE in the presence of the endothelium, whereas this vasodilatory effect was not present in SHR, suggesting an impaired NO release. Chronic treatment with losartan partly corrected this dysfunction. In WKY rats, and SHR receiving losartan, the relaxant effect of D2O disappeared in the presence of L-NAME.Conclusion:Chronic treatment with losartan improved endothe-lium-dependent relaxation in SHR through an NO-dependent pathway; this effect might contribute to its antihypertensive action.

ISSN:0263-6352    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Background:Arterial hypertension contributes to the development of lipid abnormalities, as (possibly) do some antihypertensive drugs. Chronic hypercholesterolaemia (HC) accelerates the atherosclerotic process, which in turn alters the vascular response to a variety of vasoactive agonists. Because of the cholesterol-membrane fluidityionic transport relationships, it is reasonable to propose that HC of short duration, unaccompanied by vascular morphologic changes, could first alter vascular reactivity, and second lead to early functional haemodynamic abnormalities.Methods:To answer these two questions, the following study was undertaken. HC was induced by feeding New Zealand rabbits a cholesterol (4%) and cholic acid (1%)-enriched diet. The response to angiotensin II (10-11-10-8mol/l), of desendothelialized strips of aorta, mesenteric artery and vein obtained from rabbits fed during 1,2 and 3 consecutive weeks, was examined using the cascade superfusion technique.Results:HC failed to alter the aortic contractile response to angiotensin II. However, the mesenteric artery contraction decreased by 48, 52 and 74% of baseline values (P<0.01) after 1, 2 and 3 weeks of HC. In contrast, the mesenteric vein contraction was enhanced by 85, 87 and 22% of control values (P<0.01) during the same 3 weeks of HC. In these animals, renal plasma flow (para-amino-hippurate clearance) decreased from 14.6 to 11.4, 8.8 and 9.3 ml/min (P<0.01) after 1, 2 and 3 weeks of HC, while glomerular filtration rate (inulin clearance) similarly declined from 43 to 3.7 (NS), 2.3 and 2.5 ml/min (P<0.01). Although renal haemodynamic parameters significantly declined during HC, urine flow increased markedly from 381 to 664, 512 and 510 μl/min (P<0.01), and urinary sodium rose transiently from 64 to 87 μmol/min (P<0.01) after 1 week of HC.

ISSN:0263-6352    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Methods:This study investigated the effects of angiotensin II (Ang II; 10-9-10-7mol/l) on calcium releases in ventricular myocytes from normal and renal hypertensive adult rats (Goldblatt two kidney one clip). Newly isolated myocytes were loaded with fluorescent indo-1/AM and studied at rest or under electrical stimulation. The variation of the ratio of indo-1 emission (405/480 nm) was taken as a measure of cytosolic calcium variation. Five parameters were investigated from each peak systolic indo-1 ratio before and after Ang II addition: amplitude variation, duration with analysis of a rise time and a fall time, and frequency of spontaneous calcium releases.Results:The following changes were observed: (1) in unstimulated myocytes exhibiting spontaneous contractile activity, an increase in the frequency of calcium transients, at 10-7mol/l, in normal cells (+157±27%,P<0.01) and at each Ang II concentration in hypertrophied cells (+79±31%,P<0.01; +82±25%,P<0.01; +285±50%,P<0.01 at 10-9, 10-8and 10-7mol/l); (2) in stimulated myocytes, prolongation of the duration of calcium transients, explained by the occurrence of calcium releases during fall time. In addition, 50% of myocytes exhibited spontaneous releases of calcium in the interstimulus interval. The increase in calcium transient duration was statistically significant, regardless of the Ang II concentration in hypeitrophied cells (+36±20%,P<0.05; +39±18%,P0.01; +77±34%,P<0.01 at 10-9, 10-8, 10-7mol/l) and only at 10-7mol/l in normal cells (+68±22%,P<0.01). Similar results were observed in fall time.Conclusion:Thus, in both normal and hypertrophied myocytes, Ang II induced calcium release, and hypertrophied cells became increasingly sensitive to Ang II. This occurrence of calcium release is a possible cause of arrhythmias, known as ‘triggered activity'.

ISSN:0263-6352    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Introduction:We have recendy reported that urine from salt-loaded rats contains a potent natriuretic factor affecting the Na-K-Cl cotransport system, ‘cotransport inhibitory factor“ (GIF). Here we investigated the kinetics of the urinary GIF excretion that follows an oral salt load: (1) in normal rats, relative to that of atrial natriuretic peptide (ANP) and (2) in an experimental model of salt-dependent genetic hypertension (Dahl's rats).Methods:Wistar rats were orally loaded with 2% NaCl for 8 days. Urinary GIF excretion was measured by testing the inhibitory potency of urine on bumetanide-sensitive lithium efflux in lithium-loaded human erythrocytes. Plasmatic levels of ANP were measured by radioimmunoassay.Results:Plasma ANP rapidly and transiently increased during the first 24 h of salt load, decreasing thereafter to normal levels in 6–8 days. Conversely, GIF slowly increased after 24 h up to maximal constant levels after 5 days of salt loading. Dahl salt-sensitive rats exhibited highly significant increases in urinary C1F excretion compared with salt-resistant rats. In the basal state (before salt loading) urinary GIF excretion was 101 ±13 and 17.6±4.5 units/day in salt-sensitive and salt-resistant rats (n=7 for each group,P<0.001). This difference was maintained after salt loading (33801990 versus 456±159 units/day,P<0.05 at day 5).Conclusion:The results suggest that GIF is a new natriuretic factor that: (1) shares some common properties with loop diuretic drugs (fuiosemide); (2) in contrast with ANP, seems to be a long-term regulator of excess salt intake; and (3) is increased in Dahl salt-sensitive rats, probably as a compensatory mechanism against the tendency to sodium retention that characterizes this model of hypertension.

ISSN:0263-6352    

出版商:OVID    

年代:1994

数据来源: OVID