The Trial of Antihypertensive Interventions and Management (TAIM) Study. Final results with regard to blood pressure, cardiovascular risk, and quality of life.

The Trial of Antihypertensives Interventions and Management (TAIM) was a multicenter double-blind placebo-controlled clinical trial of drug and diet combinations for the treatment of mild hypertension among 878 participants, ages 21 to 65, 110% to 160% ideal weight, and with baseline diastolic blood pressure 90 to 100 mm Hg. The drugs used were placebo, chlorthalidone (25 mg/daily) or atenolol (50 mg/daily). The diets studied were usual, weight loss, sodium reduction/potassium increase. Trial end points were 6-month diastolic blood pressure change, cardiovascular risk change, and quality of life change. Either drug combined with weight loss produced the greatest blood pressure reduction of 15 mm Hg, compared to 8 mm Hg on placebo/usual diet. Adding sodium restriction to either drug did not enhance blood pressure lowering effect. Drugs outperformed diet in terms of antihypertensive effect. However, those on placebo and assigned to weight reduction who lost more than 4.5 kg and those on sodium restriction who reduced sodium to less than 70 mEq daily lowered blood pressure to a similar extent as those on either of the two drugs alone. Cardiovascular risk at 6 months relative to baseline ranged from 0.85 in weight loss/atenolol subgroup to 1.04 in the usual diet/chlorthalidone subgroup. Blacks were more responsive to chlorthalidone plus weight loss and whites to atenolol plus weight loss. Quality of life, as measured by scales of distress and well-being, was favorably affected by weight reduction. Although there were few side effects of the drugs and most patients improved on most parameters, sexual complaints were worsened among those on chlorthalidone and usual diet compared to placebo.(ABSTRACT TRUNCATED AT 250 WORDS)     

Pharmacologic and nutritional treatment of mild hypertension: changes in cardiovascular risk status

OBJECTIVE: To evaluate the 6-month change in cardiovascular (coronary heart disease) risk as a function of diet and drug therapy for mild hypertension. DESIGN: Collaborative randomized, controlled clinical trial to assess the efficacy of alternative regimens in treating mild hypertension. SETTING: Three university-based tertiary care centers-the Trial of Antihypertensive Interventions and Management (TAIM). PATIENTS: Six hundred and ninety-two men and women ages 21 to 65 years with diastolic blood pressure between 90 and 100 mm Hg and weight between 110% and 160% of ideal weight. MEASUREMENTS AND MAIN RESULTS: Patients stratified by clinical center and race were randomized into diet (usual, low sodium-high potassium, weight loss) and drug (placebo, chlorthalidone, and atenolol) groups resulting in nine diet plus drug combinations. The cardiovascular risk at 6-month follow-up was estimated relative to baseline in 692 participants using the Framingham Study model. Due to the blood pressure reduction, cardiovascular risk declined from baseline for all treatment groups (except the usual diet plus chlorthalidone group because of increased cholesterol levels). The relative cardiovascular risk at 6 months compared to baseline ranged from 0.83 in the weight loss plus atenolol subgroup to 1.03 in the usual diet plus chlorthalidone subgroup. The active drug plus weight loss groups showed the lowest relative cardiovascular risk at 6 months. CONCLUSIONS: Mild hypertension was generally reduced to desirable levels within 6 months by monotherapy. Evaluating blood pressure changes together with the risk factors indicated a differential effect on overall cardiovascular risk depending on the diet and drug used. Dietary therapy, particularly weight reduction, was important adjunctive treatment in reducing overall cardiovascular risk.     

The Trial of Antihypertensive Interventions and Management (TAIM) study. Adequate weight loss, alone and combined with drug therapy in the treatment of mild hypertension.

This report examines the effect of weight loss, alone and in combination with drugs, on diastolic blood pressure change in the Trial of Antihypertensive Interventions and Management (TAIM), which is a randomized, multicenter, placebo-controlled clinical trial of drug and diet combinations in the treatment of mild hypertension among 787 patients. Diastolic blood pressure drop (11.6 mm Hg) at 6 months among those patients who were randomized to weight reduction and placebo drug treatment was greater among those who lost 4.5 kg or more, than the 7-mm Hg drop for those who lost less than 2.25 kg or for the placebo-treated control group, and it was statistically equivalent to the reduction achieved by 25 mg of chlorthalidone or 50 mg of atenolol (11.1- and 12.4-mm Hg drop, respectively). Weight loss potentiated effects of drugs, with reductions of 18.4 mm Hg, for those patients who were taking atenolol and had a 4.5-kg or more weight loss, and of 15.4 mm Hg, for those patients who were taking chlorthalidone and had at least a 2.25-kg weight loss. We concluded that effective weight loss (greater than or equal to 4.5 kg) lowers blood pressure similarly to low-dose drug therapy and potentiates drug effects, with the apparent 4.5-kg threshold being lowered to 2.25 kg for those patients who receive chlorthalidone.     

Effect of antihypertensives on sexual function and quality of life: the TAIM Study

OBJECTIVE: To evaluate treatment of mild hypertension using combinations of diet and low-dose pharmacologic therapies. DESIGN: Multicenter, randomized, placebo-controlled clinical trial. SETTING: Three university-based tertiary care centers. PATIENTS: Patients (697) 21 to 65 years of age with diastolic blood pressure between 90 and 100 mm Hg as well as weight between 110% and 160% of ideal weight. INTERVENTION: Patients were stratified by clinical center and race and were randomly assigned to one of three diets (usual, low-sodium and high-potassium, weight loss) and one of three agents (placebo, chlorthalidone, and atenolol). MEASUREMENTS: Changes in measures of sexual problems, distress, and well-being after 6 months of therapy were analyzed. MAIN RESULTS: Low-dose chlorthalidone and atenolol produced few side effects, except in men. Erection-related problems worsened in 28% (95% CI, 15% to 41%) of men receiving chlorthalidone and usual diet compared with 3% (CI, 0% to 9%) of those receiving placebo and usual diet (P = 0.009) and 11% (CI, 2% to 20%) of those receiving atenolol and usual diet (P greater than 0.05). The weight loss diet ameliorated this effect. The low-sodium diet with placebo was associated with greater fatigue (34%; CI, 23% to 45%) than was either usual diet (18%; CI, 10% to 27%; P = 0.04) or weight reduction (15%; CI, 7% to 23%; P = 0.009). The low-sodium diet with chlorthalidone increased problems with sleep (32%; CI, 22% to 42%) compared with chlorthalidone and usual diet (16%; CI, 8% to 24%; P = 0.04). The weight loss diet benefited quality of life most, reducing total physical complaints (P less than 0.001) and increasing satisfaction with health (P less than 0.001). Total physical complaints decreased in 57% to 76% of patients depending on drug and diet group, and were markedly decreased by weight loss. CONCLUSION: In general, low-dose antihypertensive drug therapy (with chlorthalidone or atenolol) improves rather than impairs the quality of life; however, chlorthalidone with usual diet increases sexual problems in men.     

Systolic Hypertension in the Elderly Program (SHEP): antihypertensive efficacy of chlorthalidone

The Systolic Hypertension in the Elderly Program (SHEP) is a randomized, blinded test of the efficacy of antihypertensive drug treatment. In a large feasibility trial, 551 men and women who had isolated systolic hypertension and were at least 60 years old received chlorthalidone (25 to 50 mg/day) or matching placebo as the step I drug. After 1 year, 83% of the chlorthalidone group and 80% of the placebo group were still taking SHEP medications. Of those still taking chlorthalidone, 88% had reached goal blood pressure (BP) without requiring a step II drug, and most had responded to the lower dose (25 mg/day). The BP response was similar in all age, sex and race subgroups, with an overall mean difference between randomized groups of 17 mm Hg for systolic BP (p less than 0.001) and 6 mm Hg for diastolic BP (p less than 0.001). The only common adverse effects were asymptomatic changes in the serum levels of potassium (0.5 mEq/liter lower in the chlorthalidone group, p less than 0.001), uric acid (0.9 mg/dl higher, p less than 0.001) and creatinine (0.08 mg/dl higher, p = 0.02). This study indicates that chlorthalidone is effective for lowering BP in elderly patients with systolic hypertension and sets the stage for a larger trial of the effects of such treatment on the incidence of cardiovascular disease.     

Effects of diet and sodium intake on blood pressure: subgroup analysis of the DASH-sodium trial.

BACKGROUND: Initial findings from the Dietary Approaches to Stop Hypertension (DASH)-Sodium Trial demonstrated that reduction of sodium intake in two different diets decreased blood pressure in participants with and without hypertension. OBJECTIVE: To determine effects on blood pressure of reduced sodium intake and the DASH diet in additional subgroups. DESIGN: Randomized feeding study. SETTING: Four clinical centers and a coordinating center. PARTICIPANTS: 412 adults with untreated systolic blood pressure of 120 to 160 mm Hg and diastolic blood pressure of 80 to 95 mm Hg. INTERVENTION: Participants followed the DASH diet or a control (typical U.S.) diet for three consecutive 30-day feeding periods, during which sodium intake (50, 100, and 150 mmol/d at 2100 kcal) varied according to a randomly assigned sequence. Body weight was maintained. MEASUREMENTS: Systolic and diastolic blood pressure. RESULTS: In all subgroups, the DASH diet and reduced sodium intake were each associated with significant decreases in blood pressure; these two factors combined produced the greatest reductions. Among nonhypertensive participants who received the control diet, lower (vs. higher) sodium intake decreased blood pressure by 7.0/3.8 mm Hg in those older than 45 years of age (P < 0.001) and by 3.7/1.5 mm Hg in those 45 years of age or younger (P < 0.05). CONCLUSION: The DASH diet plus reduced sodium intake is recommended to control blood pressure in diverse subgroups.     

The dietary approaches to stop hypertension (DASH) clinical trial: implications for lifestyle modifications in the treatment of hypertensive patients

Lifestyle modifications, such as weight loss, sodium restriction, and limiting alcohol consumption, are important components of the initial treatment of hypertensive patients. The Dietary Approaches to Stop Hypertension (DASH) study investigated the effects of dietary patterns on blood pressure in individuals with diastolic blood pressure between 80-95 mmHg. Two different dietary patterns were tested in this feeding study. A diet enriched in fruits and vegetables and a diet enriched in fruits, vegetables, and low-fat dairy products and low in total and saturated fat (combination diet) were compared with a control diet. Dietary intake was adjusted so that participants did not lose weight, and all study diets had comparable sodium intake (approximately 3 grams/day). All meals were provided for 459 participants for an 11-week period. Those randomized to the combination diet (n = 151) had a significant change in systolic (-5.5 mmHg; p < 0.001) and diastolic blood pressure (-3.0 mmHg; p < 0.001) after subtracting the response to the control diet (n = 154). The fruits-and-vegetables diet (n = 154) produced a significant but lesser decrease in blood pressure (systolic, -2.8 mmHg; p < 0.001 and diastolic, -1.1 mmHg; p = 0.07). Hypertensive individuals and African Americans had particularly favorable responses with blood pressure reductions, which were significantly greater than other subgroups. The combination diet was well-accepted and adherence to the diet was high (>90%) for all participants. The DASH combination diet is an effective lifestyle modification for lowering blood pressure in patients with high-normal or Stage 1 hypertension.     

Effect of dietary potassium on blood pressure, renal function, muscle sympathetic nerve activity, and forearm vascular resistance and flow in normotensive and borderline hypertensive humans

We evaluated the effect of a low potassium diet on blood pressure in normotensive (NT) and in borderline hypertensive subjects (BHT). There were 11 BHT men (age, 24.6 +/- 1.2 years) and 10 NT men (age, 23.5 +/- 1.0 years). Subjects were studied while on both low potassium, high sodium (30 meq/day, 400 meq/day) diets and high potassium, high sodium (100 meq/day, 400 meq/day) diets, each taken for 6 days. During the low potassium diet, daytime ambulatory systolic blood pressure increased in both NT (123 +/- 5 mm Hg, low potassium, vs. 116 +/- 4 mm Hg, high potassium, p less than 0.01) and BHT groups (134 +/- 3, low potassium, vs. 124 +/- 3, high potassium, p less than 0.001). Mean blood pressure was not different in NT during the two diets but was significantly higher during the low potassium diet in BHT subjects (97 +/- 2 mm Hg low potassium, vs. 92 +/- 1 mm Hg, high potassium, p less than 0.05) without change in heart rate in BHT subjects during the two diets. Low potassium diet increased the postural rise in diastolic blood pressure when subjects changed from the supine position to quiet standing (standing diastolic blood pressure for NT: low potassium, 79 +/- 2 mm Hg vs. high potassium, 72 +/- 2 mm Hg; for BHT: low potassium, 89 +/- 2 mm Hg vs. high potassium diet, 83 +/- 2 mm Hg, p less than 0.01). The effects of low potassium diet on blood pressure were not related to marked changes in renal hemodynamics, in plasma renin activity, in aldosterone, or in norepinephrine, nor to increases in forearm vascular resistance or in muscle sympathetic nerve activity. In fact, muscle sympathetic nerve activity decreased in the BHT group during low potassium compared with high potassium diets (p less than 0.001) and did not change in the NT group. Sympathetic nerve activity was also higher in BHT compared with the NT group during high potassium and low potassium diets, p less than 0.001. In the NT group, the low potassium diet was associated with lower hematocrit levels, weight gain, and increased 24 hour urinary calcium levels. After the low potassium diet, serum potassium fell in both groups, and serum phosphorus fell significantly in the BHT group.(ABSTRACT TRUNCATED AT 400 WORDS)     

Results of the Diet,Exercise, and Weight Loss Intervention Trial (DEW-IT)

National guidelines for the prevention and treatment of hypertension recommend sodium reduction, weight loss, the Dietary Approach to Stop Hypertension (DASH) diet, and regular aerobic exercise. However, no trial has assessed the efficacy of simultaneously implementing all of these recommendations. The objective of this study was to determine the effects on blood pressure and other cardiovascular disease risk factors of a comprehensive lifestyle intervention. We conducted a randomized controlled trial of 44 hypertensive, overweight adults on a single blood pressure medication. Participants were randomized to a lifestyle or control group. For 9 weeks, the lifestyle group was fed a hypocaloric version of the DASH diet that provided 100 mmol/d of sodium. This group also participated in a supervised, moderate-intensity exercise program 3 times per week. The control group received no intervention. Outcomes were ambulatory blood pressure, serum lipids, weight, and fitness. At the end of the intervention, mean weight loss in the lifestyle group, net of control, was 4.9 kilograms. In the lifestyle group mean net reductions in 24-hour ambulatory systolic and diastolic blood pressures were 9.5 mm Hg (P<0.001) and 5.3 mm Hg (P<0.002), respectively. Corresponding changes in daytime systolic and diastolic blood pressures were 12.1 mm Hg (P<0.001) and 6.6 mm Hg (P<0.001). The lifestyle group experienced mean reductions in total cholesterol (-25 mg/dL, P<0.001), low-density lipoprotein cholesterol (-18 mg/dL, P=0.005), high-density lipoprotein cholesterol (-5 mg/dL, P<0.001), net of control. In conclusion, among hypertensive overweight adults already on antihypertensive medication, a comprehensive lifestyle intervention can substantially lower blood pressure and improve blood pressure control.     

Low sodium/high potassium diet for prevention of hypertension: probable mechanisms of action

20 normotensive subjects (10 with a family history of hypertension) were investigated as to whether moderate salt restriction and/or a high potassium intake had a beneficial effect on blood pressure regulation and prevention of hypertension. In all subjects a moderate reduction of salt intake from 200 to 50 mmol/day over 2 weeks reduced the rise in blood pressure induced by various doses of noradrenaline (0.1, 0.2, and 0.4 microgram/kg/min). Furthermore, of 20 subjects 12 (8 with a family history of hypertension) responded to salt restriction with a fall in systolic or diastolic blood pressure of at least 5 mm Hg. There were no significant differences in plasma renin, aldosterone, vasopressin, and catecholamine levels between responders (salt-sensitive subjects) and non-responders, but salt-sensitive subjects had a mean baseline diastolic blood pressure which was higher than that of salt-insensitive subjects by 13 mm Hg (77.3+/-3.26 vs. 64.6+/-2.06, p less than 0.001). A high potassium intake reduced diastolic blood pressure by at least 5 mm Hg in 10 out of 20 subjects, of the 10 7 had a family history of hypertension and 9 responded to salt restriction. A high potassium intake also improved compliance with a low salt regimen, promoted sodium loss, prevented the rise in plasma catecholamines induced by a low salt diet, and increased the sensitivity of the baroreceptor reflex. These four effects occurred in the group as a whole and were probably the means by which a high potassium intake reduced blood pressure. In all subjects 2 weeks of a combined low sodium/high potassium intake reduced blood pressure rises induced by mental stress or noradrenaline infusion by 10 mm Hg. The results of this study suggest that moderate salt restriction combined with a high potassium intake helps to prevent hypertension, that salt-sensitive subjects exist, and that these individuals would profit most.     

Long-term effects of weight loss and dietary sodium reduction on incidence of hypertension

To examine the long-term effects of weight loss and dietary sodium reduction on the incidence of hypertension, we studied 181 men and women who participated in the Trials of Hypertension Prevention, phase 1, in Baltimore, Md. At baseline (1987 to 1988), subjects were 30 to 54 years old and had a diastolic blood pressure (BP) of 80 to 89 mm Hg and systolic BP <160 mm Hg. They were randomly assigned to one of two 18-month lifestyle modification interventions aimed at either weight loss or dietary sodium reduction or to a usual care control group. At the posttrial follow-up (1994 to 1995), BP was measured by blinded observers who used a random-zero sphygmomanometer. Incident hypertension was defined as systolic BP > or =160 mm Hg and/or diastolic BP > or =90 mm Hg and/or treatment with antihypertensive medication during follow-up. Body weight and urinary sodium were not significantly different among the groups at the posttrial follow-up. After 7 years of follow-up, the incidence of hypertension was 18.9% in the weight loss group and 40.5% in its control group and 22.4% in the sodium reduction group and 32.9% in its control group. In logistic regression analysis adjusted for baseline age, gender, race, physical activity, alcohol consumption, education, body weight, systolic BP, and urinary sodium excretion, the odds of hypertension was reduced by 77% (odds ratio 0.23; 95% confidence interval 0.07 to 0.76; P=0.02) in the weight loss group and by 35% (odds ratio 0.65; 95% confidence interval 0.25 to 1.69; P=0.37) in the sodium reduction group compared with their control groups. These results indicate that lifestyle modification such as weight loss may be effective in long-term primary prevention of hypertension.     

Effects of potassium on blood pressure in salt-sensitive and salt-resistant black adolescents.

This study examined the effects of increasing dietary potassium on ambulatory blood pressure nondipping status (<10% decrease in blood pressure from awake to asleep) and cardiovascular reactivity in salt-sensitive and salt-resistant black adolescents. A sample of 58 normotensive (blood pressure, 101/57+/-9/4 mm Hg) black adolescents (aged 13 to 16 years) participated in a 5-day low sodium diet (50 mmol/24 h) followed by a 10-day high sodium diet (150 mmol/24 h NaCl supplement) to determine salt-sensitivity status. Participants showed a significant increase in urinary sodium excretion (24+/-19 to 224+/-65 mmol/24 h) and were identified as salt-sensitive if their mean blood pressure increase was >/=5 mm Hg from the low to high sodium diet. Sixteen salt-sensitive and 42 salt-resistant subjects were then randomly assigned to either a 3-week high potassium diet (80 mmol/24 h) or usual diet control group. Urinary potassium excretion significantly increased in the treatment group (35+/-7 to 57+/-21 mmol/24 h). At baseline, a significantly greater percentage of salt-sensitive (44%) compared with salt-resistant (7%) subjects were nondippers on the basis of diastolic blood pressure classifications (P<0.04). After the dietary intervention, all of the salt-sensitive subjects in the high potassium group achieved dipper status as a result of a drop in nocturnal diastolic blood pressure (daytime, 69 versus 67 mm Hg; nighttime, 69 versus 57 mm Hg). No significant group differences in cardiovascular reactivity were observed. These results suggest that a positive relationship between dietary potassium intake and blood pressure modulation can still exist even when daytime blood pressure is unchanged by a high potassium diet.     

DASH (Dietary Approaches to Stop Hypertension) diet is effective treatment for stage 1 isolated systolic hypertension

Use of the DASH (Dietary Approaches to Stop Hypertension) diet, which is rich in fruits, vegetables, and low-fat dairy foods, significantly lowers blood pressure. Among the 459 participants in the DASH Trial, 72 had stage 1 isolated systolic hypertension (ISH) (systolic blood pressure, 140 to 159 mm Hg; diastolic blood pressure, <90 mm Hg). We examined the blood pressure response in these 72 participants to determine whether the DASH diet is an effective treatment for stage 1 ISH. After a 3-week run-in period on a typical American (control) diet, participants were randomly assigned for 8 weeks to 1 of 3 diets: a continuation of the control diet (n=25), a diet rich in fruits and vegetables (n=24), or the DASH diet (n=23). Sodium content was the same in the 3 diets, and caloric intake was adjusted during the trial to prevent weight change. Blood pressure was measured at baseline and at the end of the 8-week intervention period with standard sphygmomanometry. Use of the DASH diet significantly lowered systolic blood pressure compared with the control diet (-11.2 mm Hg; 95% confidence interval, -6.1 to -16.2 mm Hg; P<0.001) and the fruits/vegetables diet (-8.0 mm Hg; 95% confidence interval, -2.5 to -13.4 mm Hg; P<0.01). Overall, blood pressure in the DASH group fell from 146/85 to 134/82 mm Hg. Similar results were observed with 24-hour ambulatory blood pressure measurements. In the DASH diet group, 18 of 23 participants (78%) reduced their systolic blood pressure to <140 mm Hg, compared with 24% and 50% in the control and fruits/vegetables groups, respectively. Our results indicate that the DASH diet, which is rich in fruits, vegetables, and low-fat dairy foods, is effective as first-line therapy in stage 1 ISH.     

Effect of antihypertensive therapy on weight loss. The Trial of Antihypertensive Interventions and Management Research Group.

We report the effect of weight changes of the type of antihypertensive medication prescribed in a trial of the relative efficacy of drug and dietary measures in mild hypertension. The Trial of Antihypertensive Interventions and Management studied 878 mildly hypertensive individuals randomly assigned, in a 3 x 3 design, to no diet change, weight loss, or a low sodium-high potassium diet and to placebo, 25 mg chlorthalidone, or 50 mg atenolol. The type of drug prescribed affected weight change with all diets. The drug effect on weight change, present in all groups at 6 months, was most pronounced in those randomly assigned to the weight loss diet, where the placebo group lost 4.4 kg, the atenolol group lost 3.0 kg, and the chlorthalidone group lost 6.9 kg. The group differences were attenuated but persisted at 24 months. We suggest that the antihypertensive drug prescribed affects the success of a conjoint weight loss program and speculate that the difference between the drugs may be due to their intrinsic effects on the sympathetic nervous system and related metabolic changes.     

A double-blind parallel trial to assess the efficacy of doxazosin, atenolol and placebo in patients with mild to moderate systemic hypertension

The antihypertensive and lipid effects of doxazosin and atenolol were compared in a 10-week, double-blind, parallel, placebo-controlled study. The 129 adults enrolled had mild to moderate hypertension (average supine diastolic blood pressures for doxazosin, atenolol and placebo were 100.6, 101.0 and 99.7 mm Hg, respectively). Patients were randomly assigned to treatment with doxazosin, 1 to 16 mg daily, atenolol, 50 to 100 mg daily or placebo. Among 114 patients included in the efficacy analysis, standing blood pressure (systolic/diastolic) changed by -13/-11 mm Hg with doxazosin (n = 37), -12/-12 mm Hg with atenolol (n = 39) and +1/-1 mm Hg with placebo (n = 38). Mean reductions in blood pressure for doxazosin and atenolol were significantly greater than those for placebo (p less than 0.01), although no statistically significant differences between the active agents were noted. Serum lipid measurements were evaluable for 116 patients, and the 38 doxazosin-treated patients in this group experienced reductions in total cholesterol, total triglyceride and very low density lipoprotein cholesterol levels. Both doxazosin and atenolol demonstrated comparable acceptance profiles. Doxazosin is an effective hypotensive agent with beneficial effects on serum lipid levels.     

Comparison of the effects of diuretic therapy and low sodium intake in isolated systolic hypertension

Of 103 patients with isolated systolic hypertension, 71 were treated with diuretics and another 32 with low-sodium diet. In the 71 who were treated with diuretics, body weight decreased from 69.48 ± 1.47 to 68.60 ± 1.45 kg (p < 0.0005) and systolic blood pressure from 178 ± 2 to 152 ± 2 mm Hg (p < 0.0005). Plasma renin activity increased from 1.78 ± 0.30 to 7.32 ± 1.78 ng/ml per hour (p < 0.005) and urinary aldosterone from 10 ± 1 to 23 ± 4 μg per 24 hours (p < 0.005). The greatest decrease in systolic blood pressure occurred in patients in the low-renin group (?32 ± 2 mm Hg), whereas it decreased by 24 ± 2 mm Hg (p < 0.04) in the normal-renin group; however, blood pressure did not change significantly in the high-renin group. In the 32 patients who were treated with low-sodium diet, the 24-hour urinary sodium excretion decreased from 143 ± 10 to 48 ± 5 meq (p < 0.005), body weight decreased from 71.18 ± 2.50 to 70.17 ± 2.47 kg (p < 0.005), systolic blood pressure decreased from 174 ± 2 to 156 ± 3 mm Hg (p < 0.0005), and diastolic blood pressure decreased from 90 ± 1 to 87 ± 1 mm Hg (p < 0.01). Plasma renin activity increased from 2.25 ± 0.33 to 4.27 ± 0.43 ng/ml per hour (p < 0.005) and urinary aldosterone from 9 ± 1 to 15 ± 2 μg per 24 hours (p < 0.005). The decrease in the systolic blood pressure was related to the pretreatment 24-hour urinary sodium excretion (r = 0.40, p < 0.05). The smallest decrease in systolic blood pressure occurred in the patients with high renin values (?1 ± 9 mm Hg, n = 5), whereas the decrease in systolic blood pressure in the low-renin (n = 12) and normal-renin groups (n = 15) was similar, ?22 ± 2 mm Hg and ?21 ± 3 mm Hg, respectively (p < 0.005 compared with the high-renin group). These results indicate that both diuretic therapy and low-sodium diet are effective antihypertensive means in most patients with isolated systolic hypertension and low or normal plasma renin activity.     

Urinary sodium excretion and blood pressure in chronic psychiatric in-patients.

Studies of populations or communities with no rise in blood pressure (BP) with advancing age and low prevalence of hypertension, may provide aetiological clues on the cause of hypertension. Within westernised societies, low blood pressures have been reported amongst chronic psychiatric in-patients and closed order secluded nuns. To investigate factors associated with BP in chronic psychiatric in-patients, we surveyed the BP and lifestyle factors in 89 such subjects in low security wards in three psychiatric hospitals. The average age of examines was 48.1 years (s.d. 15.8) and the patients had been in hospital for a mean of 8.6 years (range 1.1 to 51.7 years). The mean systolic and diastolic blood pressures of this group were 122.0 mm Hg (s.d. 14.2) and 76.9 mm Hg (s.d. 8.5) respectively. This was lower than pressures obtained when they were admitted to hospital (mean systolic BP change -17.1 mm Hg (s.d. 14), paired t-test P < 0.001; mean diastolic BP change -3.7 mm Hg (s.d. 12.2), paired t-test P < 0.001). BP at examination was significantly correlated with the urinary sodium to creatinine ratio (r = 0.302, P = 0.027), but not with the urinary sodium or potassium concentrations or potassium/creatinine ratio. The change in mean systolic BP (that is, the difference in BP between admission and examination) was significantly correlated with sodium/creatinine ratio (r = 0.62, P < 0.0001), urinary sodium concentration (r = 0.27, P = 0.045) and urinary sodium/potassium ratio (r = 0.36, P = 0.008). No relationship was found between BP and the nature of the psychiatric diagnosis or the type of psychotropic medication that was being prescribed. Stepwise multiple regression demonstrated that urinary sodium creatinine ratio and age were predictive of the change in systolic BP since admission to hospital. Our study confirms previous observations of lower mean systolic and diastolic blood pressures in chronic psychiatric subjects after a long in-patient stay. This fall is related to a low urine sodium excretion and suggests that a low dietary sodium intake may, in part, account for the low BP, or the difference between BP in the stressed and relaxed state, seen in these patients.     

Comparison of antihypertensive therapies by noninvasive techniques

We compared the antihypertensive effects of the beta-blocker atenolol and the converting enzyme inhibitor lisinopril during 12 weeks of treatment in patients with mild to moderate essential hypertension. Atenolol (n = 10) significantly decreased conventionally measured blood pressure from 144/103 to 135/93 mm Hg and lisinopril (n = 9) from 150/104 to 130/92 mm Hg. Based on data derived from automated 24-h ambulatory blood pressure monitoring, atenolol decreased the average whole-day systolic pressure by 18 +/- 6 mm Hg (p less than 0.02) and the diastolic pressure by 11 +/- 2 mm Hg (p less than 0.01). Lisinopril produced decreases of 27 +/- 5 mm Hg (p less than 0.01) and 13 +/- 2 mm Hg (p less than 0.001). Examination of the 24-h blood pressure patterns showed that the efficacies of the two drugs were similar. Each appeared to be effective throughout the whole-day monitoring period, although only lisinopril significantly decreased blood pressure during the final four-h period (4 AM to 8 AM) preceding the next day's dose. Neither drug produced significant echocardiographic changes in left ventricular wall thickness or muscle mass during the short-term treatment. Lisinopril and atenolol effectively decrease blood pressure during a 24-h period. Moreover, we found that automated whole-day blood pressure monitoring is a useful tool for comparing the efficacy and duration of action of differing antihypertensive agents.     

Effect of energy-restricted diet on sympathetic muscle nerve activity in obese women.

Twenty obese women aged 45-65 years with borderline hypertension were allocated randomly to either a group with an energy-restricted diet or to a control group. Body weight, blood pressure, urinary sodium, and urinary excretion of norepinephrine and plasma volume were recorded. Resting muscle sympathetic nerve activity was measured in the peroneal nerve by tungsten microelectrodes and expressed as bursts per minute. These measurements were repeated after 3 days of semistarvation and after a body weight reduction of 7% while each patient's weight was in a steady state. After 3 days of semistarvation, only body weight was reduced, whereas after the long-term energy intake restriction, there were reductions of body weight (79.9 +/- 3.4 versus 74.1 +/- 3.4 kg; p less than 0.001), diastolic blood pressure (93 +/- 3 versus 86 +/- 4 mm Hg; p = 0.01), and muscle sympathetic nerve activity (49 +/- 2 versus 42 +/- 3 bursts/min; p less than 0.05). Other variables were unchanged. There were no changes in body weight, blood pressure, or muscle sympathetic nerve activity in the control group. We conclude that body weight decrease in obesity results in a reduction of blood pressure that is at least partially caused by a reduction of sympathetic vasoconstrictor activity.     

Intracellular sodium and the response to nitrendipine or atenolol in African blacks

The relationship between the hypotensive effect of nitrendipine (N), 20 mg/day (n = 17), or atenolol (A), 100 mg/day (n = 17), and the erythrocyte sodium [( Na]i) and potassium [( K]i) concentrations was investigated in hypertensive African blacks during a randomized double-blind study. After 6 weeks, both treatments significantly reduced supine and standing blood pressures; however, the magnitude of the decrease in supine systolic (-22.0 +/- 2.0 vs -12.1 +/- 3.4 mm Hg) and diastolic (-14.1 +/- 1.3 vs -7.6 +/- 2.1 mm Hg) pressures and in standing diastolic pressure (-16.0 +/- 1.7 vs -9.2 +/- 2.0 mm Hg) was more pronounced (p less than 0.05) in the N-treated than in the A-treated group. Pulse rate, plasma aldosterone, and plasma renin activity were lower (p less than 0.05) in the A-treated patients. Neither treatment had significant influence on [Na]i, [K]i, or ouabain-sensitive sodium efflux. The N-induced changes in supine systolic and diastolic pressure correlated (p less than 0.05) with age (r = -0.65 and r = -0.58, respectively) and pretreatment plasma renin activity (r = 0.71). Multiple regression analysis demonstrated a negative association between pretrial [Na]i and the change in systolic pressure during N treatment that was independent of age, pretreatment blood pressure, and change in pulse rate. Age and the change in supine pulse rate were also independently correlated with the change in diastolic pressure during N treatment. The results show a greater antihypertensive efficacy of N than A in the patients entered in this study and suggest that a higher intracellular sodium concentration could predict a better hypotensive response to N.