摘要:

In rats with severe two-kidney, one clip (2-K.1C) hypertension the time-course of changes in left and right ventricular (LV and RV) weight and LV dimensions was assessed following initiation of chronic treatment with minoxidil, enalapril or removal of the clipped kidney in relation to changes in blood pressure (BP) and sympathetic activity, as well as plasma and blood volumes. Minoxidil decreased BP markedly, but tolerance to the antihypertensive effect developed after 2-3 weeks. In contrast, enalapril or uninephrectomy caused a rapid and persistent normalization of BP.Significant increases in LV and RV weight occurred after 3-5 weeks of treatment with minoxidil. Left ventricular wall thickness decreased over the initial 1-2 weeks and then returned to untreated levels. Left ventricular internal dimensions showed an increase after 1-2 weeks of minoxidil, which persisted with more prolonged treatment. With enalapril, regression to normal occurred for both LV and RV weight within 1 week of treatment. Following uninephrectomy a more gradual regression took place and normal cardiac weight was not obtained until 3 weeks.Indices of sympathetic activity (plasma catecholamines, BP response to hexamethonium or heart rate) did not differ significantly in minoxidil treatment versus untreated hypertensive rats from 2 to 35 days of treatment. A significant increase in heart rate was found after 1 day of minoxidil and a decrease after enalapril. Plasma and blood volumes were elevated in minoxidil-treated rats from 7 to 35 days, as well as initially after uninephrectomy.Therefore, in 2-K.1C hypertensive rats long-term treatment with minoxidil induces both RV hypertrophy and LV eccentric hypertrophy. Changes in cardiac volume load may play a major role in the differing effects of different antihypertensive therapies on cardiac hypertrophy.

ISSN:0263-6352    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

The relationship between blood pressure and alcohol intake was examined in 2434 male and 1608 female London civil servants. These subjects had been selected from 24 000 office workers on the basis of responses to a health questionnaire. The men had an average blood pressure of 134/80 mmHg and consumed a mean of 62 g alcohol/week as beer, 28 g/week as wine or fortified wine and 18 g/week as spirits (a total of 11.8 drinks/week). The women had an average blood pressure of 133/79 mmHg and consumed 7 g alcohol/week as beer, 25 g/week as wine and 11 g/week as spirits (a total of 4.4 drinks/week). Twenty-five per cent of men and 24% of women had a casual diastolic pressure equal to or greater than 90 mmHg and were considered to have diastolic hypertension on the one occasion.There was no increase in either systolic or diastolic pressure in men until total alcohol intake exceeded 50 drinks/week. However, 1 % of all men had hypertension associated with drinking alcohol and in those with hypertension, alcohol may have been the cause in between 4 and 9%. Defining 'hypertension' as a diastolic blood pressure of 90 mmHg or above on one occasion, 12-14% of people drinking more than 50 drinks of alcohol per week had hypertension associated with this intake of alcohol, and similarly, of those with both 'hypertension' and this level of intake, 36% could attribute their high blood pressure to their alcohol consumption. More men consumed beer than spirits or wine and the relationship between a high alcohol intake and an increase in blood pressure could only be confirmed for beer consumption. However, 43% of men consumed wine as well as other drinks. When the effect of the type of drink was examined there was a tendency for a high intake of wine to be associated with a lower blood pressure. The result of this inverse association was to strengthen the positive association with beer consumption so that a beer intake of more than 2.5 pints a day (30 units/week) was associated with an increase in systolic blood pressure. A positive relationship between alcohol consumption and an elevated blood pressure was not observed in those drinking either less than 30 units of beer/week or those drinking less than 50 mixed drinks/week, either before or after adjusting for obesity and age.Women drank less than men and did not have a positive relationship between alcohol intake and blood pressure. However, systolic blood pressure was inversely associated with a spirit intake of 1-9 drinks/week (but not more than 10 drinks/week).

ISSN:0263-6352    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Casual blood pressure (BP) can predict the development of cardiovascular morbidity and mortality, but the correlations between its values and the subsequent occurrence of such complications are low. This may depend on different individual resistance to the damage produced by hypertension. However, it may also depend on the recognized inability of casual BP to reflect accurately the 24-h mean and profile BP. In order to test the latter hypothesis, 24-h BP was recorded intra-arterially (Oxford method) in 108 hospitalized subjects with essential hypertension ranging from mild to severe. The 24-h means and standard deviations (i.e. variabilities) for systolic, mean and diastolic BP obtained by computer analysis of the BP tracing were related to the rate and severity of target-organ damage (TOD) assessed by clinical examination and quantified according to a predetermined score. The results confirmed that 24-h BP may be variably different from cuff BP among subjects. For nearly any value of cuff BP, subjects in whom the 24-h mean BP was low had a lower prevalence and severity of TOD than those in whom the 24-h mean BP was high (P<0.01). Furthermore, for nearly any level of 24-h mean BP, subjects in whom the 24-h BP variability was low had a lower prevalence and severity of TOD than those in whom the 24-h BP variability was high (P<0.05).These findings demonstrate that the severity of hypertension is more closely related to 24-h mean BP than to cuff BP values. They also provide the first unequivocal demonstration that hypertension-dependent TOD also relates to the extent of BP variability. This supports the diagnostic superiority of ambulatory over more traditional BP measurements in hypertension.

ISSN:0263-6352    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Instrumented dogs were presented with two daily avoidance conditioning sessions during 12 days of continuous'saline infusion (1.3 I/day). Avoidance conditioning of sodium-loaded dogs resulted in progressive 24-h hypertension over the 12-day conditioning periods (systolic, 21 ±3 mmHg; diastolic, 15 ±1 mmHg) accompanied by a decreased 24-h heart rate (-14.8 ± 4.0 beats/min). Under these conditions, renal excretion of sodium decreased relative to sodium intake (-88 ± 19 mmol/12days) while urine volume was increased relative to water intake (0.18 ± 0.07 I/day). The sodium retention was accompanied by increased plasma sodium levels (1.8 ± 0.7 mmol/l) and decreased plasma calcium levels (-1.2 ± 0.2 mmol/l). Daily creatinine clearance decreased during the development of hypertension (-53 ± 13% per day). Subsequently, each dog was exposed to 12 days of saline infusion in the absence of avoidance sessions. Under these conditions, arterial pressure and sodium balance remained stable. It was concluded that the rapidly developing and reversible hypertension occurring in sodium-loaded dogs exposed to recurrent behavioural stress is mediated by increased levels of total body sodium.

ISSN:0263-6352    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats were started at birth on sodium diets ranging from severely deficient (9 µmol) to a regular intake (101 µmol Na+/g food). Blood pressure and sympathetic activity were assessed at 6 and 16 weeks of age. At either age, SHR on 9 µmol Na+failed to develop hypertension. Spontaneously hypertensive rats on 17µmol Na+ exhibited significant blunting of the hypertension; SHR on 26 µmol showed a small amelioration. At 6 weeks, basal plasma noradrenaline was similar in SHR and WKY on 9 and 101 µmol Na+, whereas plasma adrenaline was increased in SHR at the lowest sodium level. At 16 weeks, both catecholamines were significantly increased in SHR on the 9 and 17 µmol sodium diet versus SHR on the control diet. Blood pressure responsiveness to noradrenaline was significantly decreased on 9 µmol Na+, but to a similar extent in both strains. In contrast, the blood pressure lowering effect of ganglionic blockade was markedly blunted in SHR on 9 µmol Na+and to a lesser extent on 17µmol Na+(both for percentage and absolute decrease) and 26 µmol Na+(only for absolute fall); however, this did not occur in WKY over the diet-range used.We conclude that a sodium-deficient diet from birth prevents/blunts the development of hypertension in SHR, at least partly by decreasing the pressor effect of the sympathetic nervous system

ISSN:0263-6352    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Forty young subjects, aged 18 to 28 years, with mildly elevated blood pressure participated in a double-blind randomized three-period crossover study of the effect of sodium restriction with and without potassium supplementation on blood pressure. Dietary sodium intake was restricted for 18 weeks in which the patients received in random sequence 'slow-sodium' (90 mmol/day), 'slow-potassium' (72 mmol/day), and placebo tablets, each for 6 weeks. Mean urinary sodium excretion was 129 mmol/24 h in the slow-sodium period, 57 mmol/24 h during placebo, and 69 mmol/24 h during slow-potassium. Mean supine systolic blood pressure in the sixth week of the slow-potassium period was 3.3 mmHg lower than that at the end of the slow-sodium period (P<0.05). There was no significant difference in systolic or diastolic blood pressure between the placebo and the slow-sodium periods. The fall in systolic blood pressure in the low sodium/high potassium period was accompanied by a fall in cardiac index of 0.4 l/min per m2 body surface area (BSA) (P=0.03). Our observations suggest a small hypotensive effect of moderate sodium restriction combined with high potassium intake in young hypertensive subjects. Sodium restriction alone has little effect on blood pressure in this group. The combination of a low sodium/high potassium diet may lower blood pressure by affecting cardiac output. Reducing the dietary sodium:potassium ratio may therefore be useful in the management of early primary hypertension.

ISSN:0263-6352    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Two groups, each with nine essential hypertensive patients, were maintained on 10 mmol sodium daily over 14-17 days and treated in this sequence: (1) placebo; (2) captopril (25 or 50 mg given thrice daily) or indomethacin (50 mg given thrice daily) alone; (3) captopril plus indomethacin, and (4) captopril alone. The initial fall in mean blood pressure induced by captopril (118 ±1 to 102 ±1 mmHg) was unaffected by the addition of indomethacin. However, if indomethacin treatment preceded captopil, the antihypertensive effect was attenuated (116 ±4 to 109 ±4), and was associated with significant reductions in urinary prostaglandin and kinin excretion. Addition of captopril to indomethacin returned kinin excretion to placebo levels but did not affect indomethacin-induced reduction in prostaglandin excretion. Captopril alone stimulated plasma renin activity (PRA) fivefold; aldosterone excretion was lowered by 25% and further reduced by indomethacin. Thus, when captopril and indomethacin are administered together, the order of administration is critical to the antihypertensive effect of captopril.

ISSN:0263-6352    

出版商:OVID    

年代:1987

数据来源: OVID