摘要:

ObjectiveThe present study was undertaken to examine whether arginine vasopressin (AVP) relaxes primate coronary artery and to analyse the mechanisms of its action in reference to endothelial nitric oxide and AVP receptor subtype.MethodsIsometrical tension responses to AVP and desmopressin were recorded in isolated monkey coronary arteries.ResultsAVP (10−9to 10−7mol/l) induced a concentration-related relaxation; endothelium-denudation abolished the response. Treatment withNG-nitro-L-arginine, but not the D-enantiomer, abolished the endothelium-dependent relaxation, which was restored by L-arginine. Treatment with SR49059 and [Pmp1,Tyr(Me)2]-Arg8-vasopressin, selective inhibitors of V1receptor subtype, attenuated the relaxant response to AVP, whereas the relaxation induced by sodium nitroprusside was not affected by SR49059. Desmopressin, a V2receptor agonist, up to 10−8mol/l did not elicit relaxation.ConclusionsIt is concluded that AVP-induced monkey coronary arterial relaxation is mediated via nitric oxide synthesized from L-arginine in association with stimulation of V1receptor subtypes in the endothelium.

ISSN:0263-6352    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Purpose and methodsTo examine whether treatment for hypertensive patients prevents the progression of cerebral infarction, we performed magnetic resonance imaging (MRI) repeatedly at mean intervals of 22 months on 117 Japanese subjects aged 65–89 (mean 74 years), including 84 hypertensive patients. The patients were given various anti-hypertensive agents, and the blood pressure of each patient was monitored periodically during the observation period. Depending on the average blood pressure at the end of the follow-up period, hypertensive patients were classified into three subgroups: normotension (N), borderline (B) and hypertension (H). None had a prior history of symptomatic cerebral infarction and neurological abnormalities. The number of infarcted lesions were determined on brain MRI by two independent observers.ResultsSilent cerebral infarction (SCI) lesions were observed in 42 hypertensive subjects (50.0%) and in eight control subjects (24.2%) on enrolment The numbers of SCI lesions increased in 33 hypertensive subjects (39.3%) and three control subjects (9.1%) during the observation period. In the hypertensive subjects, an increased number of infarcted lesions was found in six of 28 subjects in group N (21.4%), 17 of 44 in group B (38.6%), and 10 of 12 in group H (83.3%). Thus, blood pressure controlled to the normal level appears to result in a lower incidence of progression of infarcted areas in patients with hypertension (N versus H,P< 0.001).ConclusionOur data indicate that an appropriate anti-hypertensive treatment reduces the risk of a cerebrovascular accident in hypertensive patients.

ISSN:0263-6352    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveTo assess regional diastolic function in patients with hypertension with or without left ventricular hypertrophy using Doppler tissue imaging, a new tool that analyzes myocardial wall motion ‘on-line’.MethodsTen normotensive subjects, 20 hypertensive patients without hypertrophy and 20 with hypertrophy (left ventricular mass index >50 g/m2.7), all men, underwent Doppler echocardiography and Doppler tissue imaging, which was performed in apical view by placing pulsed sample volume at the level of the basal and middle septum, basal and middle lateral wall, and infero-posterior wall. Peak velocities and time–velocity integrals of myocardial early (Em) and late (Am) waves and their ratios, regional deceleration time and regional relaxation time were measured in each segment.ResultsTransmitral peak E/A ratio was 1.37 in normotensive subjects, 1.01 in hypertensive patients without hypertrophy and 0.77 in those with hypertrophy (P< 0.00001). The myocardial diastolic indexes derived by Doppler tissue imaging worsened at all levels in hypertensive patients without hypertrophy compared with normotensive subjects. In hypertensive patients with hypertrophy, the majority of myocardial diastolic indexes were further impaired at the basal septal level, but only marginal differences were found in other regions, compared with indexes in hypertensive patients without hypertrophy. The main diastolic indexes were found, using separate intra-group analyses, to be more compromised at the basal septum than at other levels only in hypertophic hypertensive patients. The prevalence of regions having peak Em/Amratios < 1 increased significantly from normotensive subjects to hypertensive patients without hypertrophy, but not significantly from these to the hypertrophic group. Among pooled hypertensive patients, after adjusting for heart rate and diastolic blood pressure using multivariate models, the septal wall thickness was shown to be an independent determinant of the diastolic indexes of the basal and middle septum.ConclusionsIn hypertensive patients without hypertrophy, diastolic dysfunction is uniform along the ventricular walls, whereas in those with hypertrophy it is more evident at the basal septal level than in other walls. Overall among hypertensive patients, the diastolic properties of the interventricular septum worsen as the thickness of the septal wall increases, in the presence and in the absence of hypertrophy.

ISSN:0263-6352    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveTo assess the renal benefits of cicletanine (CIC) in diabetic rats with renal impairment.MethodsHemi-nephrectomized streptozotocin-diabetic Wistar–Kyoto Izmo rats (WKYIzm) (10 weeks old) were randomly assigned to receive vehicle or a low or high dose of CIC (30 or 100 mg/kg per day, orally) for 12 weeks.ResultsThe blood pressure was raised slightly but not significantly in this model. An anti-hypertensive effect of CIC was not significantly observed. However, the subdepressor doses of CIC significantly and dosedependently decreased urinary albumin excretion. These results were confirmed by morphological analysis of kidneys in each group of rats. CIC treatment significantly and effectively protected against an increase in the percentage of focal glomerular sclerosis. CIC did not affect urinary and blood glucose concentrations at either dose.ConclusionsThese results suggest that CIC has a renal-protective action, which is not related to improvement of diabetes or of high blood pressure in this model. The action might be due to the reduction of intraglomerular capillary pressure, although the mechanism remains to be further investigated.

ISSN:0263-6352    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

BackgroundPatients with high pulse pressures have an increased risk for cardiovascular events. Drugs that selectively decrease high pulse pressure may be of interest for these patients. Such drugs have a more pronounced effect on large arteries than on resistance vessels.ObjectiveTo compare the selectivity to large arteries of the new nitric oxide donor sinitrodil with the classic nitrate isosorbide dinitrate in healthy young men in order to investigate whether it is possible to develop drugs that act more selectively on large arteries.DesignThe study had a double-blind, 5-way cross-over design. In randomized order, subjects received a single oral dose of 10 mg sinitrodil, 20 mg sinitrodil, 40 mg sinitrodil, isosorbide dinitrate and placebo. Measurements were performed before and 45 min after administration of the drugs. Between each drug administration, at least 3 days of wash-out was allowed.MethodsThe effects of the drugs on large arteries and resistance vessels were assessed by their effects on brachial artery compliance and total peripheral resistance, respectively.ResultsBrachial artery compliance increased gradually with increasing doses of sinitrodil (by 10, 20 and 27% with 10, 20 and 40 mg sinitrodil, respectively). Total peripheral resistance index decreased with isosorbide dinitrate (by 11%) and 40 mg sinitrodil (by 7%), while it remained unchanged with 10 mg and 20 mg sinitrodil.ConclusionsThe results of this study show that it may be possible to develop drugs with a higher selectivity for large arteries. Such drugs may be good candidates to decrease high pulse pressure without substantially decreasing mean and diastolic blood pressures.

ISSN:0263-6352    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveWe evaluated the effect of two calcium channel blockers, verapamil and felodipine, on heart rate variability in hypertensive patients.DesignTime and frequency domain measures of heart rate variability were obtained from 24 h Holter recording in 25 previously untreated hypertensive patients without left ventricular hypertrophy, before and after 3 months of verapamil slow-release treatment (240 mg once daily) or felodipine extended-release treatment (10 mg once daily).ResultsBlood pressure values decreased with both drugs. Measures of heart rate variability, comparable at baseline in the two groups, were unchanged after felodipine. After verapamil, the average RR interval, the square root of the mean of the squared differences between all adjacent normal RR intervals (r-MSSD) and the percentage of differences between all adjacent normal RR intervals > 50 ms (pNN50), measures of vagal modulation of heart rate, increased (from 735 ± 67 to 827 ± 84 ms,P< 0.001; from 30 ± 10 to 44 ± 15 ms,P< 0.001; and from 3 ± 2 to 7 ± 6%, P < 0.01, respectively) and were higher than after felodipine. The coefficient of variation, a measure that compensates for heart rate effects, increased only after verapamil (from 5.8 ± 1.3% to 6.6 ± 1.0%;P< 0.05). High frequency power and its coefficient of component variance, both representing the vagal modulation of heart rate, increased after verapamil (from 5.33 ± 0.29 to 5.80 ± 0.27 ln units,P< 0.001 and from 1.9 ± 0.3 to 2.2 ± 0.25%;P< 0.05). Finally, the low to high frequency power ratio, an indicator of sympathovagal balance, with a high value suggesting a sympathetic predominance, decreased after verapamil (from 2.16 ± 0.41 to 1.36 ± 0.35;P< 0.001), confirming the improvement in vagal modulation of heart rate.ConclusionIn hypertensive patients, despite a comparable anti-hypertensive effect, verapamil, but not felodipine, has favourable effect on cardiac autonomic control.

ISSN:0263-6352    

出版商:OVID    

年代:1999

数据来源: OVID