ISSN:0194-911X    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Data from a representative sample of the U.S. adult population obtained during 1971–1975 were analyzed to provide a profile of blood pressure (BP)levels and related nutritional and sociodemographic factors. Older adults (aged 55–74 years) had a twofold greater prevalence of high BP than younger adults (25–54 years), and older black persons had the highest rates. Isolated systolic elevation was uncommon under 54 years of age, but occurred in 5% to 10% of adults over 55 years and was less common than systolic-diastolic elevation. In older adults, body mass (weight/height) had the strongest relationship to BPof all the nutritional variables. Alcohol consumption and dietary calcium and phosphorus were associated with high BP, but dietary sodium and salt use were not. The serum calcium/phosphorus ratio and serum urate were significantly higher in older adults with high BP. In general, the variables associated with elevated BP in older adults were similar to those in younger adults, although the strengths of the associations differed. Associations of factors useful for nonpharmacologic prevention and management of high BP in older persons were suggested from this survey.

ISSN:0194-911X    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Blood pressure (BP) and associated factors were determined in 1737 men in a remote Kenyan agricultural community. Systolic BP showed no significant rise with age until after 54 years; diastolic BP showed a small rise with age. Both systolic and diastolic BP correlated with weight independent of age. Systolic and diastolic BP correlated positively with casual urinary sodium/potassium and negatively with potassium/creatinine ratios. Both systolic and diastolic BP correlated significantly with the number of years of education, as did urinary sodium/potassium and sodium/creatinine ratios. Potassium/creatinine ratios were negatively correlated with the number of years of education. Blood pressure and urinary sodium/creatinine ratios were significantly lower in subsistence farmers compared with those in other occupations, and potassium/creatinine ratios were significantly higher. Two pilot studies of Luo tribesmen showed a strong correlation between casual urinary electrolyte ratios and those derived from 24-hour urine samples and a greater variance of sodium excretion between these people than that found within individuals. These results suggest that a relationship between BP and casual urine electrolyte estimations may be identifiable in communities where there is less day-to-day dietary variation. They also suggest that some of the changes in BP associated with urbanization could be mediated by changes in dietary electrolytes.

ISSN:0194-911X    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Twenty-three moderately obese middle-aged men with previously untreated hypertension (World Health Organization classification 1–2) were evaluated to assess the effects on blood pressure (BP) of a diet restricted in energy (fats and carbohydrates) but unrestricted in sodium (Group 1) compared to a diet restricted in energy and sodium (Group 2). The patients were randomly allocated to either of the two groups and were comparable in age, sex, weight, and BP. The same energy- and sodium- restricted diet was given to both groups, but the intake of Group 1 (n = 13) was supplemented with dietary sodium. The average urinary sodium output for Group 1 was 192 ± 39 mmol/24 hr at baseline and 200 ± 56 mmol/24 hr during the diet. For Group 2 (n = 10), which remained on the initial diet, urinary sodium excretion changed from 188 ± 53 mmol/24 hr at baseline to 97 ± 32 mmol/24 hr (p < 0.001). Intraarterial BP, cardiac output (CO), plasma volume, circulating norepinephrine (NE), and urinary NE were measured at baseline and at the end of the dieting periods. Before the dietary sodium supplement while on the initial diet, the patients in Group 2 showed a reduction in body weight from 97.3 ± 10.5 kg to 88.6 ± 9.9 kg (p < 0.001). Heart rate (HR) and urinary NE output were significantly reduced in comparison with baseline, but intraarterial BP was unchanged. No change in cardiopulmonary blood volume, CO, or stroke volume (SV) was observed. Total blood volume was unchanged, but it was relatively increased when corrected for body surface area (BSA) or body weight. Group 2 had a significant reduction in body weight of from 98.2 ± 9.6 kg to 89.5 ± 9.3 kg (p < 0.001). Significant reductions were also observed in intraarterial BP, HR, CO, circulating NE, and urinary NE compared with baseline. In comparison to Group 1, Group 2 also had a mean arterial pressure that was significantly reduced (p < 0.05). Total blood volume was unchanged during restriction of dietary sodium and energy. In conclusion, we found that hemodynamic adjustment and BP reduction were associated with weight reduction only when the dietary sodium was also restricted. The results indicate a reduction of sympathetic nervous tone in both groups, probably as a consequence of energy restriction. How normal sodium intake offsets the hypotensive response to weight reduction is not known.

ISSN:0194-911X    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

In 25 outpatients with essential hypertension, sodium sensitivity, defined as the difference in mean arterial pressure (AMAP) between 2 weeks of high-sodium (300 mmol per day) and 2 weeks of low-sodium (LS) intake (50–100 mmol per day), was studied in relation to the plasma norepinephrine (NE) level, NE release, and pressor response to intravenous NE. In addition, forearm blood flow (FBF) was measured by plethysmography. There were two control periods of regular sodium intake, one of 4 weeks' duration at the beginning of the study and one of 2 weeks' duration at the end. The AMAP ranged from +18 to − 8 mm Hg. The eight patients in whom AMAP was greater than 10 mm Hg were regarded as salt-sensitive. When compared with salt-insensitive subjects, saltsensitive patients had higher plasma NE levels in the control period (p < 0.05) and after 2 weeks of HS intake (p < 0.01). Sodium sensitivity was directly related to the change in plasma NE between the HS and LS periods (p < 0.001). The NE release decreased in salt-insensitive subjects whereas it increased in salt-sensitive patients between the LS and HS periods. Changes in NE release were directly related to sodium sensitivity (p < 0.05). The pressor response to NE was not significantly influenced by changes in sodium intake. The FBF fell in salt-sensitive patients and increased in salt-insensitive subjects between the LS and HS periods. Sodium sensitivity was directly related to the change in forearm vascular resistance (p < 0.01). Our data indicate that changes in adrenergic activity and in vascular resistance contribute significantly to sodium sensitivity.

ISSN:0194-911X    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Ouabain-resistant Na and Li effluxes in erythrocytes from 18 normal subjects and 19 hypertensive subjects were studied in fresh cells that contained about 9 mmol Li and 2.5 or 6.5 mmol Na per liter of erythrocytes after intact cells had been incubated for 5 hours in 110 mM Li, 40 mM Na medium, with or without ouabain 10′‴4M. Outward Na cotransport was estimated at both internal Na concentrations as the furosemide-sensitive unidirectional22Na efflux from erythrocytes into a Na freemedium containing 75 mM MgCI2. The changes in furosemide-sensitive outward Na transport between the two levels of internal Na were considered as a measure of the response of Na cotransport to the changes in internal Na within its physiological range. At both levels of internal Na, outward Na cotransport was reduced in the majority but not in all of the patients with essential hypertension (p < 0.05 at 2.5 mmol; p < 0.001 at 6.5 mmol). The ratio of the changes in Na cotransport to those in internal Na was lower in the hypertensive patients than in the control subjects (17.2/xmol/liter red blood cells/hr/1 mmol in internal Na increase vs 42.2, p < 0.001). The Li-Na countertransport was increased in a few patients with essential hypertension, with no relationship to cotransport. We conclude that, in essential hypertension, the outward Na + K cotransport is impaired in fresh erythrocytes not treated with PCMBS (2,5 p-chloromercuribenzene sulfonate) or nystatin, even when internal Na is around its physiological range.

ISSN:0194-911X    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Although animal studies have shown that cardiopulmonary receptors regulate the release of antidiuretic hormone (ADH), human studies have produced conflicting results. Consequently, we studied 17 normal healthy men to determine the ADH response to selective unloading (decreased stretch) of cardiopulmonary low-pressure receptors by thigh cuff inflation in the supine position. Thigh cuff inflation of 30 to 40 mm Hg decreased the central blood volume and right atrial pressure (cardiopulmonary receptor load), while mean arterial pressure and pulse pressure were unchanged (arterial baroreceptor load). Thigh cuff inflation to this level did not alter plasma osmolality or cardiac output. Plasma ADH increased an average of 67% (p < 0.01) following thigh cuff inflation compared to the preceding supine baseline. After thigh cuff deflation (n = 6), the ADH decreased toward preinflation values. We conclude that selective unloading of the cardiopulmonary receptors in humans increases plasma ADH levels.

ISSN:0194-911X    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

The amount and biochemical properties of renin excreted by anesthetized dogs were investigated to elucidate the significance of urinary excretion in the metabolism of renin. Mean arterial blood pressure was 127 ± 4 mm Hg, renal blood flow was 170 ± 8 ml/min, glomerular filtration rate, 38.6 ± 2.3 ml/min, and urine flow rate, 0.37 ± 0.09 ml/min (n = 11). Urinary renin concentration (URC) was 9.2 ± 2.1 ng angiotensin I (ANG I)/ml-hr (n = 11), as determined by radioimmunoassay for ANG I generated by incubation with semipurified homologous renin substrate. The ANG I-producing activity was inhibited by more than 90% by a specific antibody to dog kidney renin. The renin secretion rate from the left kidney into the renal vein was 76.4 ± 13.3 ng ANG 1/ml-hr per min (n = 11), and the simultaneous urinary excretion rate of renin was 2.3 ± 0.4 ng ANG 1/ml-hr per min(n = 11). Molecular weight of the urinary renin was 40,000 daltons. The pH dependent curves of the angiotensin-forming capacity of renin showed an optimum between pH 5.5 to 6.0, and the estimated Michaelis constant was 0.42/J, M. These biochemical parameters were similar to the findings in the case of renin in the plasma and the kidney. Moreover, neither acid nor trypsin treatment altered the renin activity in the urine. Thus, the active form of renin with a molecular weight 40,000 was excreted into the urine in dogs. Urinary excretion of renin was a small percentage of the renin secretion rate, thereby indicating the minor role of urinary excretion in the metabolism of renin.

ISSN:0194-911X    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Three stable monoclonal antibodies to rat angiotensinogen were obtained by fusing myeloma cells with spleen cells from Balb/c mice injected with pure rat angiotensinogen. They were screened by their binding to pure iodinated angiotensinogen and to insolubilized angiotensinogen in a solid phase assay. The tilers of the three antibodies varied from 1/3500 to 1/35000, their dissociation constants from 2.5 × 10″8M to 3.8 × 10″10M, and the sensitivity of the assay ranged from 200 to 10 pmol of pure angiotensinogen. These monoclonal antibodies did not recognize either angiotensin peptides or angiotensinogen from other species, except for mouse angiotensinogen, which crossreacted with the different antibodies from 0 to 25%. Rat cerebrospinal fluid angiotensinogen, plasma des-angiotensin I-angiotensinogen, and plasma angiotensinogen were equally recognized by these monoclonal antibodies. Contrary to what was observed for a polyclonal antiserum, the monoclonal antibodies failed to inhibit the renin-angiotensinogen reaction in vitro.

ISSN:0194-911X    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

This study assessed the contributions of the sympathetic nervous system and arginine vasopressin to the onset of one-kidney, one-wrap (1K1VV) renal hypertension in rats fed a high sodium diet. Two weeks before renal wrap or sham wrap, rats were given a high sodium diet and water ad libitum. At 3 days postwrap, resting mean arterial pressure (MAP) was significantly greater in renalwrapped rats. The contributions of the sympathetic nervous system and vasopressin to blood pressure (BP) were assessed by ganglionic blockade and vascular vasopressin receptor antagonism, respectively. Depressor responses to ganglionic blockade were significantly greater in the normotensive rats as compared to the hypertensive rats. Administration of vasopressin antagonist caused a significant fall in pressure only in wrapped rats. In addition, enhanced pressor responses to bolus injections of vasopressin were observed in hypertensive rats. These results indicate that during this phase of the hypertension there is an activation of the vasopressin pressor system without an increase in neurogenic function. Equalization of arterial pressure occurred only when both systems were blocked, regardless of the order of blockade, which indicated that the sympathetic nervous system and vasopressin interact to maintain the hypertension. Comparison of depressor responses to the blocking agents revealed that the interaction is compensatory in nature since the contributions of the sympathetic nervous system and vasopressin to the maintenance of arterial pressure were greater when the other system was blocked.

ISSN:0194-911X    

出版商:OVID    

年代:1984

数据来源: OVID