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:

A new portable device for the indirect measurement of arterial blood pressure was successfully applied to detect proxysmal hypertension and circadian fluctuation of blood pressure in patients with phaeochromocytoma. The device utilizes the volume-oscillometric technique, it is equipped with a microprocessor and allows long-term automatic monitoring of indirect blood pressure in the human finger. Compared with conventional fully automated portable devices of the arm-cuff type, our current equipment is lighter, less noisy, and causes less discomfort. With this device repeated measurements can be made without causing stress or discomfort, and without disturbing sleep. The arterial pressure measurement obtained using this device was reliable and reproducible. In some patients certain symptoms, possibly due to phaeochromo-cytoma, had been observed for several years before the study, although hypertension had not been identified. While these patients had consistently high circulating catecholamine levels, nocturnal falls in blood pressure were clearly documented. This suggests that plasma catecholamines released from the phaeochromocytoma, though excessive, may be of less physiological importance than other regulatory mechanisms concerned with circadian fluctuation of blood pressure, e.g. the sympathetic nervous system and/or hypothalamo-pituitary-adrenal system. This new device has proved to be a reliable means of monitoring long-term blood pressure and is useful in the diagnosis of paroxysmal hypertension in patients with phaeochromocytoma.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

The effect of a dietary sodium restriction (15 mmol/day) on the development of adrenocorticotrophic hormone (ACTH) hypertension was examined in six normal male subjects. When ACTH (1 mg/day) was given for 5 days to subjects on a sodium-restricted diet, systolic blood pressure rose (116 ± 4 to 125 ± 4 mmHg,P< 0.001), while diastolic blood pressure was unchanged. There was a modest antinatriuresis (cumulative Na+balance, 59 ± 2 mmol) which was reflected in a small rise in exchangeable body sodium (65 ± 15 mmol); plasma concentrations of active renin and angiotensin II both fell during ACTH treatment. Plasma volume rose (2.8 ± 0.2 to 3.6 ± 0.16 I,P< 0.01) while extracellular fluid volume was unchanged. Plasma concentration of atrial natriuretic peptide (ANP) rose to more than twice basal. Glomerular filtration rate (inulin clearance) increased (111 ± 9 to 131 ± 7 ml/min,P< 0.001), renal plasma flow, measured as the rate of para-aminohippurate (PAH) clearance, was unaitered and calculated filtration fraction rose.Dietary sodium restriction did not, therefore, prevent an ACTH-induced increase in blood pressure. The increase in plasma volume with ACTH is not dependent on renal sodium retention and is associated with increased concentrations of ANP. When these data are compared with findings previously reported in subjects given the same dose of ACTH when on normal or high sodium intakes, it is clear that, although the action of ACTH in raising blood pressure is not dependent on exogenous sodium or extracellular fluid volume expansion, sodium retention can modify the level of blood pressure attained.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Glucocorticoid-induced hypertension in rats has been studied using long-term, low-dose dexamethasone treatment. Dose-related increases in systolic blood pressure were achieved, without loss in body weight, with subcutaneous continuous infusions of 1, 2 and 5 μg dexamethasone per day, respectively, for 4 weeks. Rats treated with 10 μg dexamethasone per day lost weight at a rate of 10 g per week. Lower doses caused a significant reduction in weight gain compared with controls. Renin, aldosterone, plasma sodium and potassium concentrations were unaffected by dexamethasone treatment. Plasma atrial natriuretic peptide (ANP) concentrations were deceased by 40–50% by dexamethasone. These decreases were negatively correlated with increases in systolic blood pressure and haematocrit. Glucocorticoid-induced decreases in ANP contrast with ANP increases in response to mineralocorticoid treatment in rats with deoxycorticosterone-induced hypertension. Plasma concentrations of the endogenous glucocorticoid, corticosterone, were suppressed to the same very low levels by 5 and 10 μg dexamethasone per day; 1 and 2 μg doses were less effective. Unlike mineralocorticoid-induced hypertension, the pressor effects of dexamethasone were ameliorated but not abolished by dietary sodium restriction and were unaffected by sodium loading. Two micrograms of dexamethasone reduced plasma ANP in rats on either high- or low-sodium diets by 29 and 34%, respectively. We conclude that low-dose infusions (

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

The mechanisms causing the release of plasma inactive renin (PIR) area still unclear. We have investigated the role of the kidney in the release of trypsin-activable PIR from extrarenal sources in the rat, with special reference to the submandibular gland.The activation of PIR was performed by incubation with 20 mg/ml trypsin at 4°C for up to 10 min; the reaction was then terminated by addition of 20 mg/ml of soybean trypsin inhibitor.Bilateral nephrectomy resulted in a gradual, marked, sex-independent increase in PIR concentration, reaching levels 4.5 times higher than basal in 24 h (time 0: 14.8 ± 1.0 ng/ml per h; 24 h: 66.8 ± 3.4 ng/ml per h, mean ± s.d.,P< 0.001). This increase was not altered by the concomitant intravenous infusion of pressor doses of either angiotensin (Ang) II (30 ng/min) or pure mouse submandibular renin (a 20-ng intravenous bolus followed by intravenous infusion at the rate of 50 ng/h) for 4 h, but was completely prevented by prior removal of the submandibular glands, in which no activity of active renin and no inactive renin was detected.These results suggest that the post-nephrectomy increase of PIR is not dependent on feedack mechanisms of the suppressed renin-angiotensin system, but is controlled by the presence of submandibular glands in the rat.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Forearm blood flow (FABF) and forearm vascular resistance (FAVR) responses to sequential regional infusions of norepinephrine (NE) and angiotensin II (Ang II) were examined in 24 hypertensive and 18 matched normotensive subjects. Sensitivity to both vasoconstrictors, defined as the percentage increase in FAVR in response to the lowest dose of each agonist, was similar in the two groups. Also, the FABF response curve to the full range of both agonists did not differ between hypertensives and normotensives by analysis of variance (ANOVA). While the FAVR responses at the lowest doses of both NE and Ang II were similar in hypertensives and normotensives, FAVR responses in hypertensives diverged progressively from the normotensive response pattern,P< 0.01 according to ANOVA. The hypertensives achieved greater maximum FAVR levels at the highest doses of both agonists,P< 0.05 according to repeated measures ANOVA. After 10 min of ischaemic exercise, FAVR was higher in hypertensives than in normotensives (2.24 ± 0.10 versus 1.87 ± 0.08; P = 0.02, respectively). This value for FAVR was termed the minimum FAVR (mFAVR).The overall response pattern characterized by increased mFAVR, unchanged threshold sensitivity, steeper, slope, greater maximum response and similarity of responses to both NE and Ang II is most consistent with a structural augmentation of resistance responses. A model was used in an effort to increase understanding of the vessel morohology. This model suggested that an increased wall/lumen ratio, perhaps without an actual increase in vascular smooth muscle mass, played an important role in the observed FAVR pattern.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

We have examined the effect of trypsin treatment of rat plasma on the rate of angiotensin (Ang) I generation and measurement of this peptide by radio-immunoassay. Trypsin increased the renin incubation blank but did not alter the kinetics of the renin reaction with exogenous renin. The quantity of immunoreactive material detected in trypsin-treated plasma was not proportional to the volume of plasma assayed. Consequently, the level of inactive renin was dependent upon the volume of plasma subjected to the assay. This discrepancy occurred with two independent radio-immunoassay systems. The rate of Ang I generation was linear and significantly elevated following the addition of renin substrate to trypsin-treated plasma. However, if trypsin degradation of endogenous renin substrate was extensive and additional renin substrate was not provided, non-linear rates of Ang I generation occurred.Multiple additions of trypsin were necessary to activate maximally inactive rat plasma renin. Inactive renin accounted for 79 ± 2% of the total enzyme activity in normal rats. Although active renin declined following bilateral nephrectomy, the ratio of active to inactive renin did not change. The data suggest that the kidney is the primary source of inactive renin in the normal rat.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

This bibliography is produced in association with Current Opinion in Cardiology (Gower Academic Journals Ltd, UK). Each issue of the Journal of Hypertension lists papers relevant to hypertension, published over a two-month period, arranged under subject headings. A complete, updated list of the journals scanned is included. A cumulative bibliography, covering 12 months is published in the first issue (January) each year.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

The responsiveness of plasma aldosterone to an angiotensin (Ang) II infusion was assessed in normotensive young men, nine without and 13 with a family history of essential hypertension, after 7 days of low (mean urinary sodium 12 ± 10 mmol/24 h) and 7 days of high (269 ± 92 mmol/day) sodium intake. Under both conditions, the two study groups did not differ in body weight, arterial pressure, heart rate, plasma or urinary sodium and potassium or plasma renin, aldosterone or Ang II levels. However, after both dietary periods, the relationship between plasma aldosterone and plasma Ang II concentrations had shifted significantly (P< 0.01) to the right in predisposed compared to non-predisposed subjects. The sodium-related changes in adrenocortical sensitivity to Ang II were similar in the two groups. The pressor response to Ang II did not differ between the two groups of subjects. These findings suggest that, in addition to the known cardiovascular abnormalities of sympathetic, renal and ion transport mechanisms, a fourth area of disturbance involving the response of plasma aldosterone to Ang II may be present in normotensive subjects with familiar predisposition to essential hypertension.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID