ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

After the addition of valinomycin into the incubation medium, the potassium content of rat erythrocytes rapidly decreases. The rate-limiting step of this reaction is a unidirectional efflux of anions through band 3 protein. The rate of this efflux in erythrocytes of spontaneously hypertensive rats (SHR) of the Wistar-Kyoto strain, is not altered.The loss of KCI by rat erythrocytes is accompanied by a decrease in intracellular water, cell shrinking and activation of Na+-H+i exchange. The rate of Na+-H+exchange in the erythrocytes of SHR in the pre-hypertensive stage (4 weeks old) was decreased by 30%. There were no differences between 14-week-old and 28-week-old SHR and normotensive Wistar-Kyoto (WKY) rats.The half-maximal increase of the valinomycin-induced Na+-H+exchange in erythrocytes of 14-week-old WKY and SHR was observed at KCI concentrations in the incubation medium of 25 and 40 mmol, respectively. The addition of activators of protein kinase A (dibutyryl-cAMP) or protein kinase C (β-phorbol ester) resulted in an increase in the maximal rate of Na+-H+exchange, and did not modify its dependence on K+0concentration.In all groups of SHR, the rate of valinomycin-induced H+efflux from erythrocytes in the sodium-free medium was 1.5–2.5-fold higher than in age-matched WKY. Under these conditions (addition of valinomycin and inhibition of Na+-H+exchange), haemoglobin release from erythrocytes of SHR, treated with hypotonic solution, was significantly decreased. We conclude that these differences are due to the alteration of the skeleton protein organization in the erythrocyte membranes of SHR. No differences in these parameters between MNS and MHS were observed.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Twenty-four adolescent boys with a positive and 40 boys with a negative parental history of hypertension (PH+ and PH-, respectively) were studied at rest and during exercise on a bicycle ergometer at work loads ranging from 25 to 150 W. Each group was divided into fit and unfit categories on the basis of oxygen consumption at a heart rate (HR) of 150 beats/min. Blood pressure (BP) at rest averaged 114.2/68.8 mmHg in the PH+ group and 110.9/70.3 mmHg in the PH- group. Age and body weight did not differ between subgroups, although resting HR was lower in fit than in unfit subjects (P < 0.01). Oxygen consumption increased with exercise but did not differ between groups at any work level. However, systolic BP was significantly higher in the PH + group than in the PH- group at both 100 W (163.1 ± 12.3 versus 156.7 ± 12.2 mmHg) and 150 W (174.3 ± 12.5 versus 166.6 ± 10.4 mmHg, P < 0.05). These results suggest that the exaggerated BP responses to exercise, characteristic of hypertensive patients, may be present in normotensive adolescents with an increased risk of developing the disorder, and may reflect pathophysiological changes that precede sustained BP elevation.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Blood pressure measurements in 7735 middle-aged men from general practices in 24 towns in England, Wales and Scotland provide information on the prevalence of hypertension and its management in Great Britain. Despite a substantial correlation (r = 0.70) between systolic and diastolic blood pressures, individuals can show considerable discrepancies between these two measurements; they are not interchangeable. This observation has important implications for the choice of criteria used to define hypertension. However defined, the prevalence of hypertension increases markedly with age, increasing body mass index and with heavy alcohol consumption. It is not related to smoking and only to a small extent to social class. Diastolic hypertension (≥90 mmHg) was present in 26% and systolic hypertension (≥160 mmHg) in 22% of these men. In both systolic and diastolic hypertension, only one quarter of affected men could recall having been diagnosed as hypertensive by a doctor, and only one third of these were on regular antihypertensive treatment.There is a threefold variation in the prevalence of measured hypertension in the 24 towns with a trend towards higher rates in Northern England and Scotland. No relationship was seen between the prevalence rates of measured hypertension in the towns and the rates of doctor diagnosis of hypertension. Cardiovascular mortality rates in the towns were correlated with the measured prevalence rates for systolic and diastolic hypertension (r = 0J0 and r = 0.57, respectively). The geographic variations in blood pressure and hypertension in Great Britain provide a major opportunity for research into the causes of ‘essential’ hypertension.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Observer variation in blood pressure measurement following training with standard techniques has been investigated in a study of 7735 middle-aged men. The initial training produced consistent results between observers, but there were progressive deteriorations in the ensuing months. Subsequent re-training led to marked though inconsistent reductions in variation, but within 1 or 2 months, observers reverted back to an individual level of bias. The magnitude of observer variation is in line with the few other published accounts, and is sufficient to have important implications for group comparisons, clinical trials, and the clinical care of individual patients. Four methods of reducing observer variation are considered: regular re-training, self-measurement and ambulatory monitoring, automatic sphygmomanometers, and adjustment in the analysis. The adjustment procedure used in the British Regional Heart Study is described. Regular and frequent re-training with monitoring of performance, or the use of automatic machines are presently considered the two most practical methods of reducing observer variation.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

This study was undertaken to investigate further the possible role of vasopressin in the sexual dimorphism of deoxycorticosterone (DOC)-salt hypertension. The study was carried out 3 weeks after initiating treatment with DOC and salt in uninephrectomized male and female rats. Mean arterial pressure (MAP) was lower in female than in male DOC-salt hypertensive rats (177 ± 7 versus 198 ± 4 mmHg;P< 0.01). Mean arterial pressure did not differ between male and female normotensive control rats. Increases in MAP in response to graded i.v. infusions of vasopressin were markedly attenuated in female normotensive and hypertensive rats, but there was no sex difference in pressor responses to i.v. phenylephrine. Baroreflex sensitivity was reduced in both male and female DOC-salt rats, but to a greater extent in males (P< 0.01). Diminished pressor responsiveness to vasopressin and a smaller impairment of baroreflex sensitivity may contribute to the reduced development of DOC-salt hypertension in female rats.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

The ratio of the plasma level of β-thromboglobulin (β-TG) to platelet factor 4 (PF-4) which is regarded as a most reliable indicator of platelet activationin vivo,was followed in 52 subjects at various stages of essential hypertension according to the WHO classification. These comprised 30 cases at stage 1,19 cases at stage II and three cases at stage III, and 20 age-matched normotensive control subjects. The observed p-TG:PF-4 ratio in the hypertensive patients was 4.59 ± 0.20, which was significantly higher than the value of 3.13 ± 0.19 recorded in the normotensive control subjects. According to the WHO classification, p-TG:PF-4 ratios in hypertensive patients at stages I, II and III were 3.93 ± 0.19, 5.31 ± 0.35 and 6.56 ± 0.12, respectively. The β-TG:PF-4 ratio revealed a tendency of platelet activation to increase with advanced progress of hypertensive vascular lesions.These results suggest that the abnormal platelet function observed in patients with essential hypertension plays an important role in the development of hypertensive vascular complications.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

The blood pressure and heart rates of seven normotensive shift workers were monitored automatically for 24 h with a non-invasive ambulatory method on 3 different days. The first monitoring session took place at the end of an ordinary work period of morning shifts, the second on the first day of a period of night shifts, and the third on the last day of a period of night shifts. The circadian blood pressure rhythm, which showed a normal pattern during the daytime work shift, was totally reversed from the first day of the night shift. The blood pressure rhythm closely followed the sleep-wakefulness cycle. The changes in circadian heart rate rhythm were not as pronounced as those in blood pressure but showed a similar trend.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID