High blood pressure in older Americans. The First National Health and Nutrition Examination Survey

Centenarians and supercentenarians: a black swan. Emerging social, medical and surgical problems

The Black Swan Theory was described by Nassim Nicholas Taleb in his book “The Black Swan”. This theory refers to “high-impact, hard-to-predict, and rare events beyond the realm of normal expectations”. According to Taleb’s criteria, a Black Swan Event is a surprise, it has a major impact and after the fact, the event is rationalized by hindsight, as if it had been expected. For most of human history centenarians were a rare and unpredictable phenomenon. The improvements of the social-environmental conditions, of medical care, and the quality of life caused a general improvement of the health status of the population and a consequent reduction of the overall morbidity and mortality, resulting in an overall increase of life expectancy. The study of centenarians and supercentenarians had the objective to consider this black swan and to evaluate the health, welfare, social and economic consequences of this phenomenon.

Community-based blood pressure measurement by non-health workers using electronic devices: a validation study

Introduction

Population monitoring and screening of blood pressure is an important part of any population health strategy. Qualified health workers are expensive and often unavailable for screening. Non-health workers with electronic blood pressure monitors are increasingly used in community-based research. This approach is unvalidated. In a poor, urban community we compared blood pressure measurements taken by non-health workers using electronic devices against qualified health workers using mercury sphygmomanometers.

Method

Fifty-six adult volunteers participated in the research. Data were collected by five qualified health workers, and six non-health workers. Participants were randomly allocated to have their blood pressure measured on four consecutive occasions by alternating a qualified health worker with a non-health worker. Descriptive statistics and graphs, and mixed effects linear models to account for the repeated measurement were used in the analysis.

Results

Blood pressure readings by non-health workers were more reliable than those taken by qualified health workers. There was no significant difference between the readings taken by qualified health workers and those taken by non-health workers for systolic blood pressure. Non-health workers were, on average, 5–7 mmHg lower in their measures of blood pressure than the qualified health workers (95%HPD: −2.9 to −10.0) for diastolic blood pressure.

Conclusion

The results provide empirical evidence that supports the practice of non-health workers using electronic devices for BP measurement in community-based research and screening. Non-health workers recorded blood pressures that differed from qualified health workers by no more than 10 mmHg. The approach is promising, but more research is needed to establish the generalisability of the results.

The relationship between blood pressure and serum parathyroid hormone with special reference to urinary calcium excretion: the Tromsø study

The aim of the present cross-sectional epidemiological study from Tromsø, Northern Norway, was to evaluate the relation between blood pressure and serum PTH, and to examine whether this relation can be explained by a blood pressure-induced increase in urinary calcium. Ten thousand-four hundred and nineteen subjects were invited to participate and 8,128 attended. Those with serum calcium outside the reference range (2.20-2.60 mmol/l), with increased serum creatinine (upper limit 120 micromol/l for men and 100 micromol/l for women) and those using antihypertensive medication were excluded. Three thousand- six hundred and twenty subjects had complete data on outcome measures. Height, weight, blood pressure, serum calcium, PTH, and creatinine were measured and smoking status recorded. A morning urine sample was collected and urinary calcium, sodium and creatinine measured. The urinary calcium/urinary creatinine ratio (Uca/Ucr) and urinary sodium/urinary creatinine ratio (Una/Ucr) were calculated. There was a significant association between both systolic and diastolic blood pressure and serum PTH. The Uca/Ucr increased with increasing blood pressure. However, the Uca/Ucr did not affect the association between blood pressure and serum PTH in a multiple linear regression model. The relationship between blood pressure and serum PTH was also seen in subjects with similar Uca/Ucr, and a negative association between serum PTH and the Uca/Ucr was found. In conclusion, blood pressure and serum PTH are associated. This association cannot be explained by the urinary calcium excretion alone.

Effect of calcium supplementation on blood pressure in patients with secondary hyperparathyroidism

The aim was to study the effect of calcium supplementation 477 mg twice daily on BP in patients with secondary hyperparathyroidism during an intervention study (6 weeks) and after 954 mg during a short study (3 h). The intervention study was a placebo-controlled, double-blind, cross-over, while the short study gave a placebo and calcium in random order on separate days. The participants were obtained from an epidemiological survey in Tromsø 1994-1995 that included more than 27.000 subjects. The re-examination was performed in 2000/2001 at the University Hospital of North Norway, Norway. There were 18 subjects with secondary hyperparathyroidism and 28 control subjects in the intervention study while there were 14 cases and 8 control subjects in the short study. The results showed that in the subjects with secondary hyperparathyroidism after calcium supplementation in the intervention study there was an increase in serum calcium from 2.28 +/- 0.09 to 2.36 +/- 0.06 mmol/l (mean +/- SD) and a decrease in serum PTH from 8.6+/-1.6 to 6.5+/-2.4 pmol/l. However, there was no significant difference in either systolic or diastolic BP between calcium supplementation and placebo (138.3 +/- 21.0 vs 135.9 +/- 17.0 mm Hg and 80.9 +/- 11.1 vs 78.9+/-9.5 mm Hg, respectively). Similar results were seen in the control group. In the short study, serum calcium increased and serum PTH decreased after oral calcium, but the BP did not differ as compared to when placebo was given. To conclude, in the present setting we did not find any effect on BP by calcium supplementation in subjects with moderate secondary hyperparathyroidism.

Role of weight loss and polyunsaturated fatty acids in improving metabolic fitness in moderately obese, moderately hypertensive subjects

OBJECTIVE

While the exact regulatory interactions between blood pressure (BP) and obesity are not completely understood, weight loss provides an alternative to pharmacological treatment of hypertension. The intent of this repeated measures study of mild-moderate hypertensive, moderately obese subjects (34 females/18 males) was to determine if the reduction in BP following weight loss could be further affected by modifying the fatty acid (FA) composition of the hypocaloric diet.

METHODS

BP, insulin sensitivity (Si), and lipid parameters were assessed before and after a 10-week calorie-restricted period. Subjects were randomized to one of three dietary groups differing in FA composition. Reduced body weight was maintained for a further 4 weeks and body composition assessment, BP and heart rate measurements were repeated.

RESULTS

Weight loss (10%) in obese hypertensive subjects resulted in substantial improvements in BP, Si and lipid profile. There was no additional effect on the reduction in BP by the type of FA consumed in the diet. Following weight loss, there was a trend for omega-3 FAs to have a protective effect on fat-free mass loss (compared to omega-6 FA Group and saturated FA Group) and a trend to further enhance Si. There were significant improvements in circulating lipid profiles independent of the dietary FA intervention following the weight loss. The improvements in BP and body composition were maintained during the weight-loss maintenance period. The type of fat consumed had minor differential effects on some of the measured metabolic outcomes.

CONCLUSION

These results provide strong support for modest weight loss as a treatment for hypertension.

Relation of cellular potassium to other mineral ions in hypertension and diabetes

To investigate the role of intracellular potassium (K(i))and other ions in hypertension and diabetes, we utilized (39)K-, (23)Na-, (31)P-, and (19)F-nuclear magnetic resonance (NMR) spectroscopy to measure K(i), intracellular sodium (Na(i)), intracellular free magnesium (Mg(i)), and cytosolic free calcium (Ca(i)), respectively, in red blood cells of fasting normotensive nondiabetic control subjects (n=10), untreated (n=13) and treated (n=14) essential hypertensive subjects, and diabetic subjects (n=5). In 12 subjects (6 hypertensive and 6 normotensive controls), ions were also measured before and after the acute infusion of 1 L of normal saline. Compared with those in controls (K(i)=148+/-2.0 mmol/L), K(i) levels were significantly lower in hypertensive (132.2+/-2.9 mmol/L, sig=0.05) and in type 2 diabetic subjects (121.2+/-6.8 mmol/L, sig=0.05). K(i) was higher in treated hypertensives than in untreated hypertensives (139+/-3.1 mmol/L, sig=0.05) but was still lower than in normals. Although no significant relation was observed between basal K(i) and Na(i) values, saline infusion elevated Na(i) (P<0.01) and reciprocally suppressed K(i) levels (142+/-2.4 to 131+/-2.2 mmol/L, P<0.01). K(i) was strongly and inversely related to Ca(i) (r=-0.846, P<0.001), and was directly related to Mg(i) (r=0.664, P<0.001). We conclude that (1) K(i) depletion is a common feature of essential hypertension and type 2 diabetes, (2) treatment of hypertension at least partially restores K(i) levels toward normal, and (3) fasting steady-state K(i) levels are closely linked to Ca(i) and Mg(i) homeostasis. Altogether, these results emphasize the similar and coordinate nature of ionic defects in diabetes and hypertension and suggest that their interpretation requires an understanding of their interaction.

Calcium from dairy products, vitamin D intake, and blood pressure: the Tromso Study

BACKGROUND

The present epidemiologic study was conducted in Tromso, Northern Norway, in 1994-1995.

OBJECTIVE

The objective was to evaluate the relation between calcium intake from dairy products and the intake of vitamin D on systolic and diastolic blood pressure.

DESIGN

Subjects who were taking drugs for hypertension or heart disease, those taking calcium tablets, subjects reporting cardiovascular disease, and pregnant women were excluded, leaving 7543 men and 8053 women aged 25-69 y for analysis. Calcium and vitamin D intakes were calculated from a food-frequency questionnaire.

RESULTS

After correction for age, body mass index, alcohol and coffee consumption, physical activity, cigarette smoking, and vitamin D intake, there was a significant linear decrease in systolic and diastolic blood pressure with increasing dairy calcium intake in both sexes (P < 0.05). However, the difference in blood pressure between subjects with the highest and those with the lowest calcium intake was </=1-3 mm Hg. Similarly, with increasing blood pressure there was a significant (P < 0.001) linear decrease in age-adjusted calcium intake from dairy sources; the difference between the highest and the lowest blood pressure groups was 3-10%. Vitamin D intake had no significant effect on blood pressure.

CONCLUSIONS

There is a negative association between calcium intake from dairy products and blood pressure. However, although the effect of calcium on blood pressure appears to be small, calcium could have a significant effect on primary prevention of cardiovascular diseases.

Relation between low calcium intake, parathyroid hormone, and blood pressure

In a population health survey in 1995, serum parathyroid hormone (PTH) was measured in 1113 subjects, aged 30 to 79 years, and was found to be elevated (>6.9 pmol/L) in 118 subjects. In 1998, this group and 131 subjects with normal PTH levels were invited for reexamination, and 82 and 90 subjects from each respective group attended the follow-up. At the follow-up, 72 subjects had elevated and 100 had normal serum PTH levels. Those with elevated serum PTH levels (8 subjects with hyperparathyroidism were excluded) had significantly lower serum calcium levels and intake of calcium than those with normal PTH (2.24+/-0.09 and 2.29+/-0.10 mmol/L [mean+/-SD] and 400.3+/-227.3 and 592.1+/-459.6 mg/d, respectively; P<0.01). Serum levels or intake of vitamin D did not differ between the 2 groups. Subjects with elevated PTH in both 1995 and 1998 had significantly lower bone mineral content and bone mineral density in the lumbar spine than did those with persistently normal PTH levels (P<0.05). In the females, but not in the males, the systolic and diastolic blood pressures were significantly higher in those with elevated serum PTH (158.0+/-27.5 versus 141.5+/-19.2 mm Hg and 90. 5+/-13.6 versus 82.6+/-8.6 mm Hg, respectively; P<0.01). This difference was even more pronounced when those with persistently elevated PTH were considered separately. In conclusion, reduced intake of calcium is frequently associated with high levels of serum PTH. This is associated with moderately reduced bone mineral content and bone mineral density in the lumbar spine. In women, high levels of serum PTH are also associated with markedly increased blood pressure.

Regular walking increases peak limb vasodilatory capacity of older hypertensive humans: implications for arterial structure

BACKGROUND

Although regular aerobic exercise has been shown to lower arterial blood pressure in older adult humans with essential hypertension, the mechanisms responsible for this hypotensive effect remain largely unknown.

OBJECTIVE

To examine the hypothesis that the reduction in arterial blood pressure in older hypertensive humans with regular exercise is accompanied by evidence of a change in arterial structure.

METHODS

We measured peak limb vascular conductance, a well-established noninvasive measure of arterial structure, both in the forearm (untrained limb) and in the calf (exercise-trained limb) of 22 older adults (aged 51-74 years) with stage 1 or 2 essential hypertension. Eleven subjects walked 3-4 days/week at a mild exercise intensity (45% of heart rate reserve) for 6 months. Eleven other subjects served as nonexercising controls.

RESULTS

Maximal oxygen consumption of subjects in the exercise group increased by 17% (P < 0.05) with no change in body mass and body fat. Systolic and diastolic arterial blood pressures at rest were reduced by 7 +/- 4 and 5 +/- 2 mmHg, respectively (P < 0.05). There were roughly 20% increases in peak forearm blood flow and peak forearm vascular conductance (both P < 0.05). Similar increases in peak calf blood flow and vascular conductance were observed (both P < 0.01). There were no significant changes in any of these variables over the same time period for the nonexercising controls.

CONCLUSIONS

The decrease in resting blood pressure in older adults with stage 1 or 2 essential hypertension in response to regular aerobic exercise is associated with an increase in peak limb vascular conductance, which could be due in part to favorable changes in arterial structure. These exercise-induced functional and, possibly, structural changes are not confined to the exercise-trained limbs, but rather are more systemic in nature. These apparent beneficial changes in limb vasodilatory capacity and vascular structure can be produced with a mode, intensity, and frequency of aerobic exercise that can be tolerated and is commonly performed by older adults.

Regulation of blood pressure with calcium-dependent dopamine synthesizing system in the brain and its related phenomena

The effects of calcium on blood pressure regulation remain controversial. Although the mechanism by which calcium increases blood pressure when it is given intravenously and acutely has been elucidated, that by which calcium reduces blood pressure when it is supplemented chronically and slightly through daily diet is unclear. From a number of animal experiments concerning the effects of calcium on blood pressure, we believe that calcium ions have two separate roles in the regulation of blood pressure through both central and peripheral systems: (1) calcium ions reduce blood pressure through a central, calcium/calmodulin-dependent dopamine-synthesizing system and (2) calcium ions increase blood pressure through an intracellular, calcium-dependent mechanism in the peripheral vasculature. These concepts were applied to elucidate the mechanisms underlying hypertension in spontaneously hypertensive rats (SHR) and changes in blood pressure in other experimental animals, and the following conclusions were reached. The decrease of the serum calcium level in spontaneously hypertensive rats (SHR) causes a decrease in calcium/calmodulin-dependent dopamine synthesis in the brain. The subsequent low level of brain dopamine induces hypertension. The increase in susceptibility to epileptic convulsions and the occurrence of hypertension in epileptic mice (El mice) may be linked through a lowering of calcium-dependent dopamine synthesis in the brain, and epilepsy and hypertension may be associated. Exercise leads to increases in calcium-dependent dopamine synthesis in the brain, and the increased dopamine levels induce physiological changes, including a decrease in blood pressure. Cadmium which is not distinguished from calcium by calmodulin, activates calmodulin-dependent functions in the brain, and increased dopamine levels may decrease blood pressure. In this report, our studies are considered in light of reports from many other laboratories.

Dietary calcium supplementation and dopamine-beta-hydroxylase in spontaneously hypertensive rats

Spontaneously hypertensive 4-week-old male rats were fed, before and after the onset of hypertension, with either commercial chow (control) or commercial chow combined with different forms of milk proteins with or without calcium supplementation. After 40 weeks, rats were still hypertensive, and dopamine-beta-hydroxylase enzyme activity measured simultaneously in serum and adrenal was found to be higher than in the controls. The enzyme activity in rats fed diets with milk proteins was increased significantly in both serum and adrenal compared with the control, and such enhancement was significantly higher than that observed in animals fed the commercial diet supplemented with calcium (1.2%), suggesting that dietary calcium intake associated with dietary protein of high digestibility, such as casein, potentiates the endogenous mechanisms regulating the homeostasis of calcium more than calcium supplementation itself. Moreover, the selective and additive effect of diets supplemented with milk proteins and calcium on adrenal enzyme activity clearly suggests a relationship between cardiovascular diseases involving the genesis of hypertension and stress mechanisms through the hypothalamo-pituitary adreno-sympathetic axis.

Oral calcium supplementation reduces intraplatelet free calcium concentration and insulin resistance in essential hypertensive patients

We evaluated the effect of oral calcium supplementation on blood pressure, calcium metabolism, and insulin resistance in essential hypertension. After receiving a standard diet with 500 mg of calcium per day during a 4-week period, 20 nondiabetic, essential hypertensive patients were randomized in a double-blind fashion to receive oral calcium supplementation (1500 mg of calcium per day) or placebo for 8 weeks. At the end of the 4-week period of low-calcium diet and after the 8-week period of intervention, we measured blood pressure (by both office and 24-hour ambulatory blood pressure monitoring), calcium-regulating hormones [urinary hydroxyproline and serum osteocalcin, parathormone, and 1,25(OH)2-vitamin D3], intraplatelet free calcium concentration, fasting plasma glucose and insulin levels, and the insulin-sensitivity index (euglycemic-hyperinsulinemic clamp). Compared with patients maintained at low calcium intake, essential hypertensive patients under oral calcium supplementation significantly reduced serum osteocalcin (from 22.2 +/- 1.9 to 17.9 +/- 2.0 micrograms/L; P = .0015), parathormone (from 4.20 +/- 0.38 to 3.30 +/- 0.36 pmol/L; P = .0003), and 1,25(OH)2-vitamin D3 (from 98.0 +/- 11.0 to 61.6 +/- 5.7 pmol/L; P = .0062). Likewise, we found a significant reduction in intraplatelet free calcium concentration (from 35.9 +/- 1.2 to 26.5 +/- 0.8 nmol/L; P = .0005) and fasting plasma insulin levels (from 71.8 +/- 5.9 to 64.6 +/- 6.2 pmol/L; P = .05) and a significant increase in the insulin-sensitivity index (from 2.89 +/- 0.77 to 4.00 +/- 0.95 mg.kg-1.min-1; P = .0007). None of these parameters were significantly modified in patients maintained at low calcium intake. Office and 24-hour mean values of systolic and diastolic blood pressure did not change after 8 weeks of oral calcium supplementation or placebo.

Genetic and environmental influences on blood pressure in elderly twins

We used 289 pairs of Swedish twins reared apart or together to evaluate the importance of genetic and environmental influences on blood pressure. Unlike other twin and family studies, the adoption/twin design allows a distinction between estimates of the importance of shared rearing environments and genetic effects. Genetic factors were observed to play an important role for individual differences in blood pressure. Model-fitting analyses suggested upper limits of heritability for systolic and diastolic blood pressures in the entire sample of 0.44 and 0.34, respectively. More interestingly, substantial influences of shared family effects accounting for up to 27% of the variation were also revealed. Effects of correlated environment, which might reflect, for example, the intrauterine environment, existed to some extent later in life. The influence of genetic factors tended to decrease across age groups for systolic blood pressure (0.62 in individuals less than 65 years old; 0.12 in those 65 years and older) but not for diastolic blood pressure (0.22 for the middle-aged group; 0.26 for the older group). However, this declining trend for systolic blood pressure did not reach significance (chi 2 = 8.07, df = 4, P = .09).

Dietary calcium and blood pressure in experimental models of hypertension. A review

More than 80 studies have reported lowered blood pressure after dietary calcium enrichment in experimental models of hypertension. The evidence presented here suggests that dietary calcium may act concurrently through a number of physiological mechanisms to influence blood pressure. The importance of any given mechanism may vary depending on the experimental model under consideration. Supplemental dietary calcium is associated with reduced membrane permeability, increased Ca(2+)-ATPase and Na,K-ATPase, and reduced intracellular calcium. These results suggest that supplemental calcium may limit calcium influx into the cell and improve the ability of the VSMC to extrude calcium. This could be a direct effect of calcium on the VSMC or an indirect effect mediated hormonally. The calcium-regulating hormones have all been found to have vasoactive properties and therefore may influence blood pressure. Furthermore, CGRP and the proposed parathyroid hypertensive factor are both vasoactive substances that are responsive to dietary calcium. Therefore, diet-induced variations in calcium-regulating hormones may influence blood pressure. Modulation of the sympathetic nervous system is another important way that dietary calcium can influence blood pressure. There is evidence of altered norepinephrine levels in the hypothalamus as a consequence of manipulations of dietary calcium as well as changes in central sympathetic nervous system outflow. Dietary calcium has also been shown to specifically modify alpha 1-adrenergic receptor activity in the periphery. In some experimental models of hypertension, dietary calcium may alter blood pressure by changing the metabolism of other electrolytes. For example, the ability of calcium to prevent sodium chloride-induced elevations in blood pressure may be attributed to natriuresis. However, natriuresis does not account for all of the interactive effects of calcium and sodium chloride on blood pressure. Sodium chloride-induced hypertension may be due in part to calcium wasting and subsequent elevation of calcium-regulating hormones. Chloride is an important mediator of this effect because it appears that sodium does not cause calcium wasting when it is not combined with chloride. More attention to the central nervous system effects of dietary calcium is needed. Not only can calcium itself influence neural function, but many of the calcium-regulating hormones appear to affect the central nervous system. The influence of calcium and calcium-regulating hormones on central nervous system activity may have important implications for blood pressure regulation and also may extend to other aspects of physiology and behavior.

Plasma triglycerides and 24 hour urinary sodium excretion in elderly hypertensives. A pathogenetic connection?

Hypertension among the elderly generally represents a salt- sensitive state. However this salt-sensitivity does not appear to result from age-related increase in either sodium or salt intake. Since 20 years new trends seem to relate the role of sodium in the genesis of hypertension to a primary abnormality of electrolyte transport of cell membrane. Lipid abnormalities have also been described in untreated patients with high blood pressure. Plasma triglycerides were considerably higher (p < 0.01) in the hypertensives than in the controls. 24 hour sodium excretion was significantly lower (p < 0.0001) in hypertensives than in the controls. We have found a strong correlation among reduced sodium excretion, higher triglycerides and elevated blood pressure in the elderly. The blood pressure correlated negatively with 24 hour sodium excretion (p < 0.0001 for systolic and p < 0.002 for diastolic) and positively with plasma triglycerides (p < 0.0001 for systolic and p < 0.001 for diastolic). The poor literature regarding an association of these two alterations in human hypertensives makes our results provocative. We speculated that these alterations may be a facet of the insulin resistance commonly detectable in human hypertensives. However, further investigations are required to answer to this intriguing hypothesis.

[Evaluation of dietary intake of calcium in adult subjects with idiopathic arterial hypertension]

The calcium-intake relationship with other alimentary and anthropometric variables was investigates in a group of 60 adult (19-75 year-old) subjects, 50 females and 10 males, with essential arterial hypertension (DAP > 90 mmHg). The calcium intake was assessed by three different protocols: 24-hour food intake recall, food-frequency questionnaire and 3 day self-food intake register, repeated along with anthropometric measurements on three different occasions (2-15 month-intervals). The calcium intake assessed by the three methods, as well as the anthropometric data, were statistically similar on all three occasions. The mean data were then compared with those form the control, composed of 75 healthy subjects matched with the hypertensive group by age and sex. The patients ingested less calcium (mean +/- SD) than the controls on the daily (517 +/- 271 x 740 +/- 353 mg/d) and body-weight (8.1 +/- 5.0 x 11.4 +/- 5.9 mg/kg/d) basis. Among the males the calcium intake was the only difference found between groups and could be attributed to the lower intake of calcium-rich foods. The hypertensive females showed also higher lean-body mass (Body-mass index and arm muscle circumference). Thus the calcium intake discriminated both groups being associated with changes in other nutritional parameters only in females.

Effect of regular exercise on 24-hour arterial pressure in older hypertensive humans

The experimental goals were to determine if regular low-intensity aerobic exercise reduces 24-hour arterial blood pressure in middle-aged and older (aged 50 years or older) humans with mild diastolic (90-105 mm Hg) essential hypertension and, if so, whether this is accurately reflected by changes in casual recordings made at rest. Fourteen subjects walked 3-4 days/wk for 6 months, with 10 exercising an additional 6 months; 12 other subjects served as nonexercising controls. In the exercising subjects, maximal oxygen consumption increased 7-14% (p less than 0.05) with little or no change in body weight or fat. Conventional casual readings of systolic, mean, and diastolic arterial pressure at rest were lower (5-10 mm Hg, p less than 0.05) in all body positions after 6 months of exercise and changed little thereafter. Casual recordings made during additional circulatory measurements showed 6-month decreases of only half this magnitude and were specific to a particular blood pressure phase and body position; however, all changes were significant after 12 months of exercise. The reductions in arterial pressure at rest were associated with decreases in heart rate (p less than 0.05) and cardiac output (p less than 0.05). Ambulatory-determined 24-hour arterial pressure was unchanged after 6 months of exercise, but mean levels were slightly lower (4 mm Hg, p less than 0.05) after 12 months due to reductions in daytime (7 mm Hg, p less than 0.05) and nighttime (4 mm Hg, NS) systolic pressure; diastolic pressure was unchanged throughout the year of training. In the controls, conventionally recorded casual blood pressure levels were lower after 6 months (p less than 0.05), but no other changes were observed in any other variable over the 12 months of study. We conclude 1) regular low-intensity aerobic exercise at best produces only small reductions in 24-hour levels of arterial pressure in middle-aged and older humans with mild (diastolic) essential hypertension and 2) training-associated changes in casually determined blood pressure at rest are dependent on the measurement conditions and, most importantly, do not necessarily reflect the magnitude or even the direction of changes in arterial pressure throughout an entire day.

Evaluation of labetalol in elderly patients with essential hypertension

Labetalol was evaluated in a multicenter, placebo-controlled study of elderly patients (greater than or equal to 60 years) with mild to moderate essential hypertension. After a placebo-washout period, doses were titrated from 100 mg BID to a maximum of 400 mg BID over a 6-week period. Once blood pressure control (standing diastolic blood pressure [SDBP] less than 90 mm Hg and greater than or equal to 10 mm Hg reduction from baseline) was achieved or the maximum allowable dosage had been given, the dosage remained the same until the end of the study. The titration phase was followed by a 4-week maintenance period. Blood pressure control was achieved in 37/54 (69%) of the patients who were treated with labetalol compared with 21/58 (36%) of the patients who received placebo (P less than .001). Twenty-nine (78%) of those controlled on labetalol responded to doses of 200 mg or less BID, and there was no significant difference between groups with respect to orthostatic blood pressure changes. Adverse experiences were generally mild and occurred with similar frequency in the labetalol and placebo groups; six patients who received labetalol and five who received placebo withdrew from the study due to adverse experiences, but in only one case (labetalol) was the adverse experience considered drug-related. In summary, labetalol effectively and safely lowered diastolic blood pressure in the elderly without producing significant orthostatic changes.

Impact of age, race, and obesity on hypertensive mechanisms and therapy

Despite the demonstrated efficacy of traditional antihypertensive therapy in reducing blood pressure, hypertension continues to be a major cause of cardiovascular disease morbidity and mortality. Stepped-care therapy is a nonphysiologic approach that, due to potential metabolic derangements and stimulation of undesirable reflex responses, may not substantially reduce the cardiovascular and renal complications associated with hypertension or improve long-term survival in many hypertensive patients. Because of fundamental hemodynamic differences related to the age, race, and weight of hypertensive patients, drug treatment often elicits varying responses. Certain classes of drugs are not only more effective but also more appropriate from a physiologic standpoint in specific types of patients. Therapy selection based in part on hemodynamic mechanisms and demographic patterns is a more rational approach to patient management and may contribute to a better overall outcome than has been observed with conventional treatment.

Nutritional causes of renal impairment in old age

The occurrence of renal insufficiency tends to increase in late adulthood. This common complication of old age is associated with increased physical dependency, morbidity, and mortality, and a lowered quality of life. In this review, the authors will develop the thesis that dietary practices during early and middle adulthood importantly influence the risk of renal insufficiency in the elderly.

Na(+)-H+ antiport activity in skin fibroblasts from blacks and whites

The predisposition of black people to salt (NaCl)-sensitive essential hypertension may relate to racial differences in cellular Na+ metabolism. This tenet was investigated by examining the Na(+)-H+ antiport in serially passed skin fibroblasts from blacks and whites. Na(+)-dependent stimulation of the Na(+)-H+ antiport by cellular acidification resulted in a greater maximal velocity (Vmax) (mean +/- SEM) of this transport system in quiescent fibroblasts from blacks than fibroblasts from whites; the Vmax for recovery from cellular pH (pHi) of 6.6 was 5.84 +/- 0.50 versus 4.39 +/- 0.34 mmol H+/l X 20 seconds for blacks and whites, respectively (p less than 0.05). Although the Na+ concentration producing 50% stimulation of the Na(+)-H+ antiport for blacks (35.1 +/- 5.7 mM) was greater than for whites (24.1 +/- 3.5 mM), this difference was not statistically significant. No racial differences were observed in the Hill coefficient (n, 1.35 +/- 0.21 for blacks and 1.46 +/- 0.28 for whites). Compared with whites, cells from blacks exhibited a greater response to cytoplasmic acidification over the range of pHi values 6.20-6.60, as exhibited by an augmented rate of recovery in the pHi. These differences were not due to different basal pHi values or cellular buffering capacities, which were similar for blacks and whites. Na(+)-H+ antiport activity was not correlated with family history of hypertension. Increased activity of the Na(+)-H+ antiport in fibroblasts from blacks was confirmed without cellular acidification by stimulating quiescent cells with 10% human serum. This study demonstrates innate racial differences in cellular membrane Na(+)-H+ antiport activity.

PRESSÃO ARTERIAL EM FUNÇÃO DO SEXO, IDADE E LARGURA DO MANGUITO

Neste estudo medidas indiretas da pressão arterial foram comparadas, usando-se manguito de largura correta versus o de largura padrão, em 1000 pessoas. O manguito de largura correta, apropriada à circunferência do braço, foi escolhido segundo as recomendações da American Heart Association. Os resultados evidenciaram inadequação do manguito padrão na população estudada, tomando-se excessivamente largo na maioria dos braços; resultando em importante hipoestimação dos valores de pressão arterial, sobretudo nos adultos jovens, sexo feminino, e magros. Tais achados levantam a hipótese de que o uso do manguito padrão possa prejudicar o diagnóstico precoce da hipertensão arterial.

The effect of dietary salt ingestion on blood pressure of old-old subjects. A double-blind, placebo-controlled, crossover trial

To study the effect of dietary salt restriction and supplementation on blood pressure of elderly subjects, we performed a randomized, placebo-controlled, double-blind, crossover trial. Seven healthy subjects living in a long-term care facility, with a mean age of 85 and normal to borderline-hypertensive blood pressures, completed a 16-week protocol. During the double-blind cycles, subjects consumed either a low sodium (43 mmol/day) or a high sodium diet (175 mmol/day) for four weeks supplemented with placebo or salt capsules, with crossover to the other diet. Sitting diastolic blood pressure was significantly lower during the low sodium diet (69.86 mmHg +/- 3.80 vs 78.71 mmHg +/- 3.99, P less than .01), with all subjects showing decreases. Supine plasma renin activity and plasma aldosterone were significantly lower during the high sodium diet. Both low and high sodium diets were well-tolerated by subjects. Symptomatic postural hypotension and hyponatremia were not observed. We conclude that old-old subjects with borderline hypertension demonstrate salt-dependent increases in blood pressure. Without additional supportive studies, however, these results should not be generalized to any specific cohort of elderly individuals.

Awareness, treatment, and control of hypertension in the elderly in a general practice experience. Study Group on Hypertension in the Elderly

In 3858 ambulatory elderly people (age greater than or equal to 65 years) prevalence of hypertension was 67.8%. The hypertensive status was unknown to both the doctor and the patient in 21.4% of cases. More than 90% of known hypertensives were treated, but hypertension could be considered as controlled in less than 30% of them.

Differences of Ca2+ regulation in skin fibroblasts from blacks and whites

Black people have a higher propensity than caucasians toward essential hypertension. To explore the possibility that this racial difference relates to cellular Ca2+ metabolism, we measured 45Ca2+ washout and uptake and cytosolic free concentration of Ca2+ [Ca2+]i in serially passed skin fibroblasts from normotensive black and white males. Depending on the experimental conditions, 45Ca2+ washout in these cells was described by either two or three exponential functions, whereas 45Ca2+ uptake was described only by a two-exponent function. There were no racial differences in 45Ca2+ uptake and washout of unstimulated fibroblasts. However, stimulation by human serum resulted in an increase in the 45Ca2+ washout that was higher in fibroblasts from blacks than from whites. The racial differences were expressed primarily by higher values of the apparent washout rate constant (k1) of 45Ca2+ from the largest and most rapidly exchangeable cellular pool. The effect of human serum was not related to its origin (blacks vs. whites). In 2 mM Ca2+ medium and 10% serum from blacks, the respective k1 (mean +/- SEM; x 10(-2)/min) values for fibroblasts from blacks and whites were 89.68 +/- 5.23 and 73.29 +/- 4.0; in the presence of 10% serum from whites, the k1 values for cells from blacks and whites were 84.14 +/- 2.80 and 76.36 +/- 3.23 (overall significance of P less than .01). In Ca2+-deficient medium in the presence of 10% human serum, the k1 for fibroblasts from blacks and whites were 115.57 +/- 3.76 and 102.15 +/- 3.30 (P less than .05). Serum substantially increased the 45Ca2+ uptake in fibroblasts from both blacks and whites; however, racial differences were not observed. Basal levels of [Ca2+]i were not different in fibroblasts of blacks vs. whites (46.8 +/- 6.8 and 43.2 +/- 7.1 nM for blacks and whites, respectively). However, the peak response of Cai2+ transients for cell stimulated by 5% human serum was significantly higher in blacks than whites (blacks = 963 +/- 213, whites = 481 +/- 162 nM; P = .0286). We conclude that Ca2+ regulation is different in serum-stimulated fibroblasts from blacks and whites and that, at least in part, this difference may relate to a greater agonist-induced mobilization of Ca2+ in fibroblasts from blacks.

Calcium metabolism and hypertension

Returning to the patient presented today, perhaps we can now understand some of his findings. As I noted, men are more likely to demonstrate alterations in calcium metabolism associated with elevations in blood pressure. Furthermore, blacks are more likely than whites to develop hyperparathyroidism, particularly in the third and fourth decades of life. It is unlikely, however, that parathyroid hormone was responsible for the increase in this patient's arterial pressure because PTH has a vasodilating action. Moreover, the long-term response to parathyroidectomy is more likely to be an increase rather than a decrease in blood pressure. It is also unlikely that the mild elevations in the serum total calcium observed in this patient were responsible for his hypertension. Correction of hypercalcemia by surgical intervention failed to improve the blood pressure. There is little evidence that mild, protracted hypercalcemia can account for increases in arterial pressure. Finally, the patient's alcohol abuse might have contributed to his elevated blood pressure; it is possible that his hypertension was in part a reflection of the abnormal calcium metabolism he developed as a consequence of the alcohol abuse. Answers to some questions we faced when we first studied this patient more than a decade ago can be provided by the wealth of basic research and clinical investigation that has occurred since. We now know that calcium metabolism is a factor in blood pressure regulation in some humans and in some experimental models. Epidemiologic studies document a consistent association between lower dietary calcium intake and higher blood pressures in humans. An additional non-pharmacologic approach has been identified that can produce a modest but important lowering of blood pressure in a subset of hypertensive individuals. Much data show that calcium-regulating hormones have important cardiovascular actions that might account for some of the mechanisms by which increased dietary calcium lowers blood pressure. Research in this area also has set the stage for exploring another theoretical mechanism for sodium-chloride-sensitive hypertension. Finally, a theoretical mechanism(s) has emerged that could provide a pathophysiologic link between hypertension and certain high-risk populations such as blacks, the elderly, type-II diabetics, and pregnant women. The principal clinical implication derived from this work to date is the following: In patients with mild to moderate hypertension, the level of dietary calcium intake should be assessed. Patients whose intake is deficient should be encouraged simply to maintain calcium intake at 800 to 1000 mg/day.(ABSTRACT TRUNCATED AT 400 WORDS)

Risk factors in non-insulin dependent diabetes mellitus in elderly Chinese in Hong Kong

The early life environment, 24 h nutrient intake, body mass index, blood pressure and plasma zinc levels among 42 non-insulin dependent diabetic subjects living in sheltered housing were compared to 126 age and sex matched controls from the same community. A high body mass index and systolic blood pressure were the only risk factors. The association with systolic blood pressure was present only among non-obese subjects. No difference in nutrient intake was found. When nutrient intake from all 427 subjects living in sheltered housing was compared to other countries with a higher prevalence of NIDDM, the diet of Chinese subjects consisted of a lower percentage of fat calories and a higher percentage of protein and carbohydrate calories.

Salt sensitivity and systemic hypertension in the elderly

Aging in industrialized societies is accompanied by increases in the incidence and prevalence of hypertension, with a disproportionately greater increase occurring among aging blacks than among aging whites. This geriatric hypertension is generally of a salt-sensitive nature with a disproportionate frequency of isolated systolic hypertension. Although salt-taste acuity declines with age, salt sensitivity among the elderly does not appear to result from a compensatory increase in salt intake. Rather, age-related increases in salt sensitivity result, in part, from a reduced ability to appropriately excrete a salt load, which is due to a decline in renal function and to a reduced generation of natriuretic substances such as prostaglandin E2 and dopamine. Age-associated declines in the activity of membrane sodium/potassium-adenosine triphosphatase (Na/K-ATPase) may also contribute to geriatric hypertension because this results in increased intracellular sodium that may cause reduced sodium-calcium exchange and thereby increase intracellular calcium and vascular resistance. Reductions in cellular calcium efflux due to reduced calcium-ATPase activity may similarly cause an increase in intracellular calcium and vascular resistance. Increasing dietary calcium intake may represent an effective nonpharmacologic treatment for some salt-sensitive persons because it appears to reduce intracellular calcium by (1) suppressing parathyroid hormone-mediated calcium influx, (2) increasing Na/K-ATPase activity, and (3) reducing intravascular volume due to calcium-induced natriuresis.

Recent issues in antihypertensive drug therapy

Results of recent large scale treatment trials have demonstrated that aggressive management of high blood pressure prevents progression of mild hypertension to the accelerated or malignant phase and reduces incidence of stroke, congestive heart failure, and left ventricular hypertrophy. These trials mostly have utilized a diuretic-based, stepped-care approach to drug therapy, however, and have not shown a consistent beneficial effect of treatment on coronary heart mortality. In addition, the results of studies such as MRFIT have raised questions about serious risks of diuretic treatment in selected patients. These concerns have led to increased use of nonpharmacologic approaches to lowering blood pressure in patients with mild hypertension, but most patients ultimately require drug therapy. Alternative agents to diuretics now being employed as monotherapy in mild hypertension include beta-blockers, calcium channel blockers, ACE inhibitors, alpha-blockers, alpha- and beta-blockers, and, to a lesser extent, centrally-acting sympatholytics and peripheral adrenergic antagonists. Rational use of these agents primarily is based on a careful evaluation of concomitant medical conditions (see Table 3), as well as their mode of action, relative side effects, ease of administration, and cost. Age and race recently have been found to be important determinants of antihypertensive response to agents such as diuretics, beta-blockers, calcium channel blockers, and ACE inhibitors (see Table 3) and appreciation of these relative differences may affect drug selection. When these factors are taken into account, an effective and well tolerated regimen can be tailored to the individual patient. It is hoped that aggressive treatment of hypertension in the future will cause a further decline in cardiovascular mortality in the United States.

The association between blood pressure, age, and dietary sodium and potassium: a population study

We examined the relationship between blood pressure and dietary sodium and potassium intake estimated from 24 hr diet recall in a population of 584 men and 718 women 30 to 79 years old in Southern California. In men, but not women, age-adjusted systolic and diastolic blood pressure correlated significantly with dietary sodium intake. In both men and women, age-adjusted diastolic blood pressure significantly inversely correlated with dietary potassium intake. Age-adjusted systolic and diastolic blood pressure correlated significantly with the dietary sodium/potassium ratio in each sex; correlations were better for the ratio than for either sodium or potassium alone. The relationship was apparent over the whole range of blood pressure and dietary intake. A marked age gradient was apparent in men, the regression slope for blood pressure vs sodium/potassium ratio increasing with increasing age, suggesting increasing sensitivity to dietary sodium/potassium ratio with age. Adjusting for intake of other dietary variables, including calories, protein, carbohydrate, saturated fat, alcohol, calcium, and fiber, did not alter the relationships; adjusting for body mass index reduced the strength of the association in women but not in men. These results support the hypothesis that dietary sodium and potassium are related to blood pressure within a population.

Altered erythrocyte and plasma sodium and potassium in hypertension, a facet of hyperinsulinemia

Red blood cell sodium and potassium, plasma potassium, glucose and insulin responses to oral glucose load, serum urate, and plasma triglycerides were determined in a stratified subsample (n = 89) of a representative population sample (n = 1211), comprising 30 nonobese normotensive subjects with normal glucose tolerance (reference group) and 59 subjects representing each of the seven possible combinations of abnormal glucose tolerance, obesity, and hypertension. Rate of cation imbalance (red blood cell sodium greater than or equal to 7.0 mEq/L, potassium less than 92.5 mEq/L, or plasma potassium greater than or equal to 4.5 mEq/L) was 88.1% in subjects with abnormal tolerance, obesity, or hypertension, as compared with 40.0% in the reference group (p less than 0.001). These subjects were also characterized by significantly greater rates of insulin response: 60- and 120-minute postload levels of 100 mU/L or more (88.1 vs 46.7%), plasma triglycerides of 80 mg/dl or more (89.8 vs 53.3%) and serum uric acid of 5.5 mg/dl or more (61.0 vs 26.7%; p less than 0.001 for all). The rate of cation imbalance was significantly associated with each of these three biochemical correlates: insulin response (p less than 0.01), triglycerides (p less than 0.001), and urate (p less than 0.001). In the total population sample, the rate of untreated hypertension increased from 18% to 35% to 55.3% (p less than 0.001), with an increase in the number of biochemical correlates of cation imbalance in combination with glucose intolerance and obesity.(ABSTRACT TRUNCATED AT 250 WORDS)

Genetic variability in response to dietary calcium

Supplemental dietary calcium has been shown to reduce blood pressure in spontaneously hypertensive rats while restricted calcium diets cause an elevation in blood pressure. This latter nutrient effect has been enhanced by modest sodium restriction and is associated with a reduction in serum ionized calcium concentration. To determine whether alterations of dietary calcium and sodium have a similar influence on blood pressure in genetically normotensive rats, Fisher 344, Wistar Furth, and ACI rats were fed either a low (0.1%) calcium, low (0.25%) sodium diet or normal (1.0%) calcium, normal sodium (0.45%) diet from 4 weeks of age through 29 weeks of age. Indirect measurements of systolic blood pressure showed that only the Fisher 344 rats consistently responded to the low calcium/low sodium diets with an elevation of blood pressure. There was considerable variation in serum electrolytes across strains in the normal diets but all three strains experienced a reduction in ionized calcium and an elevation in phosphorus and magnesium on the restricted diets. In the Fisher 344 rats there were significant (p less than .05) inverse correlations among systolic blood pressure and serum ionized and total calcium concentrations and positive correlations among systolic blood pressure, phosphorus, and magnesium. There was no significant correlation between serum electrolytes and blood pressure in the other two strains. The data indicate that there is genetic variability in the blood pressure response to alterations in dietary calcium and sodium. The pattern of change in serum electrolytes across strains suggests that diet-induced alterations of serum electrolytes, specifically calcium, are not necessarily predictive of a pressor response. It would appear that some other calcium-sensitive physiological process involved in blood pressure regulation must respond differentially to calcium availability across strains.

Labetalol in the treatment of hypertension in elderly and younger patients

The efficacy and safety of labetalol therapy were evaluated in 20 patients 60 years and older with isolated systolic or diastolic hypertension and 19 patients aged younger than 60 years with diastolic hypertension. After a two-week placebo washout period, labetalol was titrated for up to four weeks (100-400 mg bid) until blood pressure control was achieved (standing systolic less than 160 mm Hg or greater than or equal to 10% reduction from baseline, and standing diastolic less than 90 mm Hg or a decrease of 10 mm Hg from baseline). Mean decreases in standing systolic and diastolic blood pressure from baseline were statistically significant for both age groups (greater than or equal to 60 years, -23/-13; less than 60 years, -18/-12, P less than .01). Control criteria were met in 18 (90%) older and 15 (79%) younger patients who then entered a four-week maintenance period. Sixteen (80%) of the older patients and six (32%) of the younger patients maintained blood pressure control on 200 mg or less of labetalol bid (P less than .05). Three patients, two of whom withdrew from the study, were judged to have experienced adverse events that were drug related. It was concluded that labetalol was effective and well-tolerated antihypertensive therapy in both elderly and younger patients. In addition, significantly less medication was required to achieve blood pressure control in the elderly.

The calcium paradox of essential hypertension

Three disparate observations--that calcium mediates vascular smooth muscle contraction, that calcium channel blockers lower blood pressure, and that increased dietary calcium intake can also ameliorate hypertension--constitute somewhat of a paradox. The complex interrelationships between calcium metabolism and essential hypertension are discussed in this review. Recent evidence suggests possible defects in intracellular calcium transport or in calcium binding in essential hypertension. This evidence, and the paradoxical therapeutic efficacy of both calcium channel blockers and supplemental dietary calcium, can be integrated into a single theoretic construct.

Nonpharmacological approaches to the control of high blood pressure. Final report of the Subcommittee on Nonpharmacological Therapy of the 1984 Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure

This report reviews a variety of nonpharmacological approaches used to control arterial blood pressure. Of all the modalities considered, only three had sufficient scientific support to warrant recommendation for inclusion in hypertension treatment programs. Each of these three modalities--weight control, alcohol restriction, and sodium restriction--was found to be capable not only of independently controlling blood pressure (particularly in patients with mild hypertension) but also of reducing the number and dosage of prescribed pharmacological agents, should their prescription be indicated. Weight reduction was found to reduce the risk from elevated arterial pressure as well as overall cardiovascular morbidity and mortality. However, because the rate of recidivism was exceedingly high in these studies, close and continuous patient follow-up is considered necessary. Excessive alcohol intake is associated in many studies with proportionally higher arterial pressures and an increased prevalence of hypertension. Therefore, the recommendation of moderation in alcohol consumption to less than 2 oz of ethanol daily for patients with hypertension is supported. Restriction of dietary sodium to less than 2 g/day was the only other nonpharmacological approach with sufficient support to be recommended as a treatment for hypertension. Although long-term studies are sorely lacking, sodium restriction has been shown to be manageable and safe and probably will benefit those hypertensive patients who are sodium-sensitive.

Theoretical mechanisms of dietary calcium's antihypertensive action

Theoretical mechanisms underlying dietary calcium's antihypertensive action are reviewed. Based upon known defects in the regulation of membrane Ca2+ transport and regulation of intracellular free Ca2+ concentration, we conclude that maneuvers that favorably modify calcium homeostasis such as dietary calcium supplementation or 1,25 (OH)2 vitamin D3 administration appear to favorably modify these defects. Consequent improvements in vascular smooth muscle function may mediate the reductions in blood pressure that follows chronic dietary calcium supplementation in experimental hypertension and in the clinical setting.