ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The effects of changes in dietary intake of sodium and potassium on 125l-angiotensin II binding to platelets were studied in normal subjects. We also defined binding to platelets from patients with essential hypertension and subjects with normal blood pressure. Restriction of sodium intake in normal subjects resulted in a decrease in the number of receptor sites from 6.2 ± 0.3 sites/cells to 4.1 ± 0.4 sites/cell (P<0.01) but there were no changes in affinity as measured by the Kd. Over a range of sodium intakes from 15 to 200 mmol/day there was a negative correlation between plasma concentration of angiotensin II and receptor site concentration (rs=0.57, P<0.01). Changes in dietary potassium did not affect angiotensin II binding. Angiotensin II binding was also measured in 10 patients with essential hypertension (mean blood pressure [BP] 178/107 mmHg, plasma concentrations of renin [PRC] 12 ± 2 i^U/ml and angiotensin [pANG] 1114 + 2 pg/ml) and 10 subjects with normal blood pressure (mean BP 112/74 mmHg, PRC 13 ± 2 jxlJ/ml, pANG II 13 ± 2 pg/ml). In the hypertensive patients, binding capacity and affinity (Kd=5.0 ± 0.6 × 10−10M, 5.7 ± 0.8 sites/cell) were similar to those in the normotensive subjects (Kd=4.9 ±0.8x10'1 0 M, 5.4 ± 0.5 sites/cell). Changes in sensitivity to angiotensin II in essential hypertension may not be determined at receptor level. Angiotensin II receptors in platelets respond to changes in sodium intake like receptors in arterial muscle.

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

We tested the hypothesis that in renal hypertension the increased peripheral vascular resistance of neurogenic origin might be due to a reflex through resetting of the carotid body chemoreceptors. The reflex respiratory and cardiovascular functions of the carotid bodies were studied in a one-kidney wrapped hypertension model in conscious rabbits, and compared with a control group of animals, by breathing 100% oxygen, three hypoxic gas mixtures to which were added sufficient CO2 to maintain the PaCO2 constant, and 2 and 4% CO2 in 21 % O2 and N2. In the control state (breathing room air) the renal hypertensive animals had a slightly higher respiratory minute volume, a higher level of arterial blood pressure and increased calculated systemic vascular resistance, compared with the normal group, but there was no difference in cardiac output. Hyperoxia had no consistent effect on respiration, heart rate or arterial blood pressure. Increasing degrees of isocapnic hypoxia caused the same degree of hyperventilation and bradycardia in both groups of animals. The arterial blood pressure did not change in either group but there was a transient increase in systemic vascular resistance in the renal hypertensives breathing 9 and 7.5% O2 The respiratory responses to 2 and 4% CO2 were similar in the two groups of animals. In the renal hypertensive animals, serial sections of the carotid bodies showed pathological changes, including subendothelial proliferation in vessels supplying the carotid bodies with narrowing of their lumens, fragmentation of the elastic laminae of the media, hypertrophy of the smooth muscle and extensive fibrosis with occasional haemorrhages.The capillaries, however, were normal. The rostral-caudal lengths of the carotid bodies were similar in the two groups. In view of our findings we conclude that the relatively normal carotid chemoreceptor responses in renal hypertensive rabbits may, in part at least, be the result of the carotid body blood flow through the partially occluded vessels being maintained at near normal levels by the elevated blood pressure

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The purpose of the present study was to assess the effect of chronic peripheral sympathectomy in rats on plasma vasopressin (basal and dehydrated) and on pressor sensitivity to vasopressin. Sympathectomy was produced in male Sprague-Dawley rats by daily injection of guanethidine (45 mg/kg) for 9 days. Control rats received saline over the same period. Plasma vasopressin was determined by radio-immunoassay, and pressor sensitivity was determined by monitoring mean arterial pressure response to graded injections of vasopressin (0.1-20 mil) in conscious rats. Sympathectomized rats showed ptosis and supersensitivity to norepinephrine, and had significantly greater basal and dehydrated plasma vasopressin levels than controls (10.3 ± 1.5 versus 6.2 ± 0.7, and 12.4 ± 0.9 versus 8.6 ± 1.0 pg/ml, s.e.m.respectively, P<0.05 for both). Sympathectomized rats also had an increased pressor sensitivity to vasopressin (dose response curve shifted to left, lower threshold, greater slope, P<0.001). Injection of a vasopressin pressor-antagonist, d (CH2)5 Me Tyr AVP, had no effect on blood pressure in control rats but caused a significant decrease of blood pressure in sympathectomized rats (15 ± 1.0 mmHg, P<0.001). These results suggest that chronic peripheral sympathectomy in rats is associated with increased basal and dehydrated plasma vasopressin, and increased pressor sensitivity to vasopressin. The effect of the vasopressin antagonist suggests that vasopressin may play a role in blood pressure maintenance in sympathectomized rats

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Intra-arterial (radial) blood pressure (BP) measurement was compared with the indirect cuff method in 55 healthy volunteers aged from 59-80 years (mean 68.6 ± 5.2 s.d.). On average, the cuff method underestimated systolic BP by 5 mmHg and overestimated diastolic BP by 8 mmHg. Cuff measurement underestimated systolic BP by>10 mmHg in 17 cases, and by>20 mmHg in three cases. The cuff method overestimated diastolic BP by>10 mmHg in nine cases (one>20 mmHg) and in two cases the cuff overestimated diastolic BP by>30 mmHg, compared with intra-arterial pressures. The differences correlated with pulse wave velocity, an index of arterial stiffness. A pulse wave velocity index reflecting the entire length from the aortic root to the posterior tibial artery (PWVI/ao-pt) gave a correlation (r) of 0.48 (P<0.0005) with systolic arterial/cuff (A/C) difference, a correlation of 0.43 (P<0.001) with diastolic A/C difference, and a correlation of 0.57 (P<0.00001) with the A/C difference in measurement of mean arterial pressure. A positive but weaker correlation was observed between A/C difference and PWVI aorta-femoral. Although the pressure differences were not as great in these healthy elderly subjects as in previous studies of patients suspected of having pseudo-hypertension, caution still appears to be indicated in the interpretation of cuff blood pressure measurement in the elderly.

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Noradrenergic activity was measured in the brainstem, hypothalamus and thoracic spinal cord of male and female spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats at 6 and 28-36 weeks of age. Two techniques were used, measurement of a major noradrenaline (NA) metabolite, free 3,4-dihydroxyphenylethyleneglycol (DHPG),| and measurement of the rate of decline in brain NA levels following dopamine-beta -hydroxylase (DBH) inhibition by FLA-63. There was a good correlation between the changes with age in NA turnover measured by the two techniques. NA levels and NA turnover measured by both techniques fell with age in brainstem and thoracic spinal cord in both SHR and WKY rats. In both strains these falls in turnover were associated with increases in blood pressure. However, the increase in blood pressure in the SHR was greater than in the WKY, even though NA turnover fell to a similar extent in both strains. These data show a difference in the pattern of change in NA levels and turnover in the brainstem and thoracic spinal cord compared to other brain regions and may therefore be related to the development of higher levels of blood pressure in older rats in both strains. They do not offer a simple explanation for the much higher blood pressures seen at all ages in the SHR.

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Twenty-nine patients with essential hypertension were studied while on their normal diets, on the 5th day of a high sodium diet (around 350 mmol/day) and on the 5th day of a low sodium diet (10 mmol/day). The fall in mean arterial pressure on changing from the high sodium to the low sodium diet was 9.0 ± 1.6 mmHg and the rise in the plasma renin activity in the same period was 2.52 ± 0.41 ng/ml/h, these two variables being significantly correlated (r=-0.45; P<0.02). An infusion of saralasin was given on the 5th day of the low sodium diet. A highly significant negative correlation was found between the fall in blood pressure on sodium restriction and the change in blood pressure with saralasin (r=-0.52; P<0.005); this correlation was still significant when corrected for the severity of the hypertension (r=-0.41; P=0.03) while it became non-significant if controlled for plasma renin activity on the low sodium diet (r=-033; NS). These results provide direct evidence that the fall in blood pressure which is seen on reducing sodium intake in many patients with essential hypertension is, at least in part, directly mediated by the reactivity of the renin angiotensin system.

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Several recent studies have reported the existence of additional plasma proteins in essential hypertensive patients and strains of genetically hypertensive rats. The aim of this work was to look for similar changes in a model of salt induced hypertension, the Dahl salt sensitive (DS) rat, using the sodium dodecyl sulphate (SDS) polyacrylamide gel electrophoresis. No additional proteins were found when different staining techniques were employed (Coomassie, silver). However, during the development of hypertension a characteristic change in the plasma protein pattern of DS rats occurred, which could not be detected in the majority of normotensive control animals.Treatment with nifedipine inhibited both the development of hypertension and this specific change in the plasma proteins, in spite of continuous dietary salt loading. It is postulated that the plasma protein changes reflect a regulatory phenomenon of hypertension.

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Screening for hypertension in the community leads to the identification of hypertensive people not previously detected, and those detected but inadequately treated or not treated at all. The aim of the present study was to assess the long-term efficacy of screening for blood pressure control in a general population. During 1981, 2139 parents of high school students were invited to our institute for a blood pressure measurement; 1533 persons (71.7%) attended the screening; 239 of them (15.6%) were found to be hypertensive (diastolic blood pressure s= 95 mmHg or already receiving antihypertensive treatment). Among the hypertensives, 42.3% did not know that they had high blood pressure, and only 7.5% had their blood pressure controlled by treatment. After being informed about the importance of lowering their blood pressure levels, all hypertensives were invited again to the institute for a further evaluation. Two hundred and two persons (84.5%) attended the re-examination. Of these, 154 (76.2%) were still hypertensive. Of the 202, 151 (74.7%) had contacted their physicians. The most common advice was to make further measurements of blood pressure over a period of time, followed by laboratory tests. The proportion of treated hypertensives rose from the initial 33.1 % to 53.9%, but in about half the patients normalization of blood pressure was not achieved. Physicians tended to treat only people with moderate to severe hypertension. The results of the present study, which are consistent with those observed in different socio-cultural conditions, suggest that one-time community screening for hypertension has limited efficacy in improving blood pressure control, unless it is integrated into a wider programme of health care.

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID