ISSN:0263-6352    

出版商:OVID    

年代:1990

数据来源: OVID

ISSN:0263-6352    

出版商:OVID    

年代:1990

数据来源: OVID

ISSN:0263-6352    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The pressor responses to dialyzed plasma extracts from normotensive (n=15) and essential hypertensive (n=14) human subjects were evaluated in anesthetized Sprague-Dawley rats. Hypertensive but not normotensive plasma raised mean arterial pressure (23.6 ± 3.6 versus -0.5 ± 2.5mmHg, P<0.0001), and this effect was correlated significantly with its ability to stimulate45Ca uptake in rat tail artery vascular smooth muscle (r=0.883, P<0.002). These data suggest a humoral contribution to the pathophysiology of essential hypertension in at least some individuals. The time-course and molecular weight distribution of the dialyzed plasma suggest that this effect is not due to known vasopressor substances, but to a factor we tentatively term plasma hypertensive factor.

ISSN:0263-6352    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Brachial artery wall shear phenomena were studied in 20 untreated essential hypertensive patients and in 11 normotensive controls of similar age. A pulsed-Doppler velocimeter was used to measure brachial artery internal diameter and mean cross-sectional and systolic centreline blood velocities. A coaxial-cylinder viscometer was used to measure blood viscosity at a shear rate of 96 s–1. A Poiseuille model of velocity distribution across the arterial lumen was used to determine wall shear rate and stress from, respectively, the ratio of blood velocity to arterial diameter and the product of shear rate and blood viscosity. Mean and systolic shear rates and stresses were calculated using, respectively, mean cross-sectional and systolic centreline blood velocities. Hypertensive patients had larger brachial artery diameters (P<0.001), lower systolic centreline and mean cross-sectional blood velocities (P<0.001, P<0.05), higher blood viscosity (P<0.001), lower mean and systolic wall shear rates (P<0.01, P<0.001) and lower systolic wall shear stress (P<0.05) than normotensive controls. In all subjects, mean blood pressure was negatively correlated both with mean and systolic shear rates (r = – 0.49, P<0.01; r = – 0.68, P<0.001) and with mean and systolic shear stresses (r = – 0.39, P<0.05; r =– 0.45, P<0.01). Thus the hypertensive state was associated with decreases in both mean and systolic wall shear rates, and in systolic wall shear stress. These shear abnormalities merit attention because of the atherogenic effect of low-shear conditions.

ISSN:0263-6352    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Phosphoinositide (PI) turnover, a major control mechanism of cellular function, was studied in erythrocytes of spontaneously hypertensive rats (SHR). After32P (inorganic phosphate) incorporation in intact cells, release of inositol trisphosphate (IP3) and inositol bisphosphate (IP2) from membrane fractions was measured in SHR with or without prior Ca2+stimulation. The present study revealed an increase of Ca2+-stimulated IP3release in SHR, suggesting high polyphosphoinositide phosphodiesterase activity in this model of hypertension.

ISSN:0263-6352    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

A total of 390 people undergoing routine examinations at the Portes Center, a screening center in Chicago, and at the Northwestern Memorial Hospital employee health service, underwent an in-depth battery of tests designed to explore the relationships of both intracellular erythrocyte sodium and sodium-lithium countertransport with age, race, gender, body mass index, pattern of alcohol intake, exogenous hormone use and the presence of hypertension. Erythrocyte sodium was significantly higher in blacks than in whites and in men than in women aged 20-39 years. Relationships of erythrocyte sodium with race and gender, as well as inverse associations with alcohol intake in men, and positive associations with age and the presence of hypertension in women were significant on multivariate analysis after control for other variables. Sodium—lithium countertransport was significantly higher in whites than in blacks and in men than in women aged 20-59 years. Associations of sodium-lithium countertransport with race and gender as well as positive associations of sodium-lithium countertransport with body mass index in men and women were significant on multivariate analysis after control for other variables. Age-related gender differences in both sodium-lithium countertransport and erythrocyte sodium, as well as the association of erythrocyte sodium with the presence of hypertension in women but not in men, suggest a hormonal interaction with sodium transport in the development of hypertension.

ISSN:0263-6352    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

This study examined the relationship between erythrocyte sodium-stimulated lithium countertransport (Na-Li CT) and systolic blood pressure (SBP) response to exercise in 22 white normotensive men (mean age 40.6 years) completing a submaximal (85% of target heart rate) graded exercise tolerance test. These men were assessed to be at risk of hypertension on the basis of a high normal diastolic blood pressure (DBP; 80-39 mmHg), being overweight and having a rapid resting pulse rate. Na-Li CT was positively and significantly associated with the maximal SBP reached during exercise (P<0.01) and the lowest SBP achieved during post-exercise supine rest (P<0.01). The relationship with resting blood pressure was not significant. Standing DBP was the only resting blood pressure measurement significantly associated with Na—Li CT (P<0.05). We found an association between Na-Li CT, a membrane sodium transport system associated with blood pressure and hypertension, and the maximal SBP reached during exercise, a blood pressure measurement predictive of future hypertension, in people with normotensive resting blood pressure. This suggests that altered membrane sodium transport may occur before the establishment of hypertension, and supports the possibility that Na-Li CT may be a risk factor for this disease.

ISSN:0263-6352    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Erythrocyte sodium-lithium countertransport was measured in normolipidaemic and hyperlipidaemic hypertensive patients, hyperlipidaemic normotensive patients and normal controls. Hypertension and hyperlipidaemia were each independently associated with raised sodium-lithium countertransport (by analysis of variance, P<0.01 and P<0.01). The effects were additive so that hyperlipidaemia could not explain raised sodium-lithium countertransport in hypertension. In hyperlipidaemic hypertensive patients, levels of plasma cholesterol, triglycerides, low-density lipoprotein (LDL) cholesterol and very-low-density lipoprotein (VLDL) cholesterol were increased, and high-density lipoprotein (HDL) cholesterol was reduced. Of these patients, 73.3% had a known family history of hypertension. Their normotensive first degree relatives were studied, and 48% of these also had raised sodium-lithium countertransport and abnormal plasma lipids (raised cholesterol, triglycerides and LDL cholesterol, and reduced HDL cholesterol). Relatives with normal sodium-lithium countertransport had normal lipids. Therefore, raised sodium—lithium countertransport was associated with the inheritance of both hypertension and hyperlipidaemia, and this could explain why raised sodium-lithium countertransport has been associated with a family history of both hypertension and associated cardiovascular disease.

ISSN:0263-6352    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

No adverse effect upon cognitive function has been detected during the first 9 months of treatment by a thiazide diuretic (Moduretic; Merck Sharp & Dohme, Hoddesdon, UK) or a ß-blocking agent (atenolol) of moderately elevated blood pressure in a cohort of 2630 men and women aged between 65 and 74 years. Furthermore, no association was discovered between levels of systolic or diastolic blood pressure at outset and responses to standard tests of cognitive function. This study was carried out in general practices as part of the current Medical Research Council Treatment Trial of Mild Hypertension in the Elderly.

ISSN:0263-6352    

出版商:OVID    

年代:1990

数据来源: OVID