Normotensive young men with family histories of hypertension gain weight and decrease their intraerythrocyte sodium content during a 5-year follow-up

Family history of hypertension and the risk of overweight in Japanese children: results from the Toyama Birth Cohort Study

Background

Family history can be a useful screening tool in the assessment and management of the risk for noncommunicable disease. However, no data have yet been reported on family history of hypertension and its effect on children’s overweight.

Methods

A total of 7249 Japanese children enrolled in the Toyama Birth Cohort Study were followed until 2002 (mean age: 12.3 years). Family history of hypertension was ascertained by asking children’s parents whether children’s biological parents or grandparents had doctor-diagnosed hypertension. Child overweight was defined according to international criteria for age- and sex-specific body mass index.

Results

The prevalence of child overweight at age 12 was 21.7% for males and 15.9% for females. After adjusting for family structure, parental employment status, and lifestyle factors, we found that a maternal family history of hypertension was positively associated with the risk of child overweight at age 12 (adjusted odds ratio [OR] 1.21, 95% confidence interval [CI] 1.04–1.39). The adjusted OR increased from 1.16 (95% CI 0.99–1.35) to 1.42 (95% CI 1.04–1.92) to 4.75 (95% CI 1.35–16.69) as the number of family members with hypertension increased from 1 to 2 to 3, respectively. There was no significant difference in the prevalence of overweight between children with a paternal family history of hypertension and those without.

Conclusions

A maternal family history of hypertension was positively associated with the risk of overweight in children at age 12.

Effect of L-arginine infusion in normotensive subjects with and without a family history of hypertension

BACKGROUND

Experimental studies have shown that nitric oxide (NO) generation in the kidney from L-arginine participates in the regulation of renal function. Our purpose was to study the effect of infusion of L-arginine (1, 5, and 10 mg/kg/min) on blood pressure (BP), renal hemodynamics, and urinary excretion of sodium and albumin in normotensive subjects with a family history of either severe hypertension (FHSH, N = 17) or mild hypertension (FHMH, N = 20) and in control subjects (N = 18) without a hereditary predisposition for hypertension.

METHODS

The glomerular filtration rate (GFR) and renal plasma flow (RPF) were measured by renal clearances of Cr51 ethylenediaminetetraacetic acid and paramino-hippurate. Renal tubular reabsorption of sodium was estimated by lithium clearance. To evaluate the effect of L-arginine infusion on the L-arginine/NO pathway, we measured the NO-metabolite nitrate in plasma, and urinary excretion of cGMP, the second messenger of NO. The derivative at an L-arginine dose of 7.5 mg/kg/min was used as a measure of sensitivity to L-arginine.

RESULTS

There was no difference in baseline systolic BP between the groups, but diastolic BP was significantly higher in FHSH compared with control subjects (P < 0.05). L-arginine caused a significant increase in urine flow, urinary excretion of albumin and sodium, and lithium clearance in all groups. FHSH showed a significantly decreased sensitivity to L-arginine with respect to urine flow rate (P = 0029) compared with FHMH and control subjects. L-arginine caused a significant decrease in the GFR in FHSH (P < 0.02) and control subjects (P < 0.001), but in FHMH, the decrease did not reach statistical significance (P = 0.097). There was no difference in sensitivity to L-arginine with respect to BP, RPF, or GFR between the three groups. In all patients, there was a significant positive relationship between Delta urine flow rate or Delta urinary sodium excretion and Delta GFR during infusion of L-arginine (P = 0.003 and P = 0.03, respectively). Plasma nitrate and urinary cGMP decreased in all groups during the L-arginine infusion.

CONCLUSION

L-Arginine infusion in normotensive subjects caused an enhanced urine flow rate and urinary sodium and albumin excretion and a slight reduction in GFR. The effect of L-arginine on the urine flow rate was significantly less pronounced in subjects with a family history of severe hypertension, which may indicate a tubular disturbance in hypertension.

Ambulatory systolic blood pressure is related to the deletion allele of the angiotensin I converting enzyme gene in young normotensives with parental history of hypertension

The aim of the present study was to evaluate the relationship between the angiotensin I converting enzyme (ACE) gene polymorphism and ambulatory blood pressure in young normotensive males with (n=45) and without (n=100) family history of hypertension. Twenty-four hour and daytime systolic blood pressure was significantly higher in subjects with a parental history of hypertension. Ambulatory blood pressure values did not differ significantly across ACE genotypes in subjects with negative family history of hypertension. In subjects with a parental history of hypertension, there was a significant positive association between the D allele of the ACE gene polymorphism and 24-h, daytime and nighttime systolic blood pressure. For twenty-four hour systolic blood pressure there was an average 9 mmHg difference between subjects with DD and II genotypes. The results indicate that in normotensive subjects with a genetic predisposition to hypertension, ambulatory systolic blood pressure is related to the D allele of the ACE gene.

Impaired glucose and insulin metabolism in borderline hypertension

This study investigated glucose and insulin metabolism in borderline hypertension (BHT) defined as repeated diastolic blood pressures (DBP) of 85-94 mmHg. Seventy-five BHT and 75 age-matched normotensive (NT, DBP < or = 80 mmHg) men were recruited from a population screening programme. Plasma lipoproteins were determined and an oral glucose tolerance test was performed (WHO criteria). Fasting insulin was significantly higher in the BHT group (17.2 vs 14.2 mU/ml, p < 0.001), whereas fasting blood glucose levels were similar in the two groups, indicating a reduced insulin sensitivity. The BHT group had significantly lower levels of HDL cholesterol and higher levels of plasma triglycerides, VLDL cholesterol and VLDL triglycerides. When adjusted for BMI these differences disappeared, whereas the basal insulin levels remained significantly elevated (F = 10.7, p < 0.001). These results indicate that an altered glucose and insulin metabolism is present already in the early stages of hypertension. They also suggest that these disturbances are only partly dependent on BMI. This supports the hypothesis that reduced insulin sensitivity could be of importance in the early phases of essential hypertension.

Insulin sensitivity is more related to fat distribution than to heredity for hypertension in normotensive men

The insulin-mediated glucose disposal rate was assessed during a euglycemic hyperinsulinemic clamp in 16 normotensive men (mean age, 41 +/- 5 years) with positive family histories of hypertension and mild overweight (PFHO) and in 25 men with negative family histories of hypertension (NFH). The control group was divided into one group with normal body weight ([NFHN] n = 11) and a second group with a similar degree of overweight ([NFHO] n = 14) as in the group with PFHO. Systolic and diastolic blood pressures were significantly greater in subjects with PFHO as compared with the NFHN group. Blood glucose and plasma insulin at baseline and during the insulin clamp did not differ between the three groups. Insulin sensitivity, expressed as the glucose disposal rate per total body weight, was significantly (P < .01) decreased in PFHO subjects (7.7 +/- 3.0 mg/kg/min) and in NFHO subjects (7.1 +/- 3.5 mg/kg/min) as compared with NFHN subjects (11.1 +/- 4.0 mg/kg/min). In multivariate analysis using body mass index, waist to hip ratio, and blood pressure as predictor variables, the waist to hip ratio was significantly related to both baseline plasma insulin (r = .70, P < .0001) and insulin sensitivity (r = -.71, P < .0001). In the present study, insulin sensitivity was related to body weight and fat distribution, whereas no difference was found regarding insulin sensitivity in subjects with or without positive family histories of hypertension.

Increased response to physical and mental stress in men with hypertensive parents

Blood pressure and heart rate responses to isometric handgrip exercise were studied at age 31 and after 5 years in young nonhypertensive men with positive family histories of hypertension (n = 13) and in those with negative family histories of hypertension (n = 13) for two generations to test whether subjects with positive family histories established a pattern of increased blood pressure and heart rate responses during the 5-year follow-up period. At follow-up the response to mental stress (Stroop's color word test) was also studied. Baseline blood pressure and heart rate at rest did not differ, initially or at follow-up, between the groups. At the initial examination, absolute blood pressure levels were significantly higher during isometric handgrip exercise just before exhaustion in subjects with positive family histories. At follow-up the absolute blood pressure level (p < 0.001) and the blood pressure responses (p < 0.01-0.001) were found to be significantly increased during handgrip exercise in subjects with positive family histories compared with subjects with negative family histories. In subjects with positive family histories the diastolic blood pressure response was significantly higher (p < 0.01) at follow-up than initially and was significantly related (r = 0.70, p < 0.01) to changes in baseline diastolic blood pressure during the follow-up period. In subjects with negative family histories the systolic blood pressure response was somewhat lower at follow-up than initially. During the mental stress test, the blood pressure response was significantly greater in subjects with positive than with negative family histories.(ABSTRACT TRUNCATED AT 250 WORDS)

Increased waist/hip ratio, metabolic disturbances, and family history of hypertension

To test whether nonhypertensive subjects with a two-generation positive family history of hypertension (PFH) are characterized by disturbed glucose metabolism, 16 men (38 +/- 6 years old) with PFH and 25 subjects matched for age and with negative family histories of hypertension (NFH) were recruited. Blood pressure; serum lipids; erythrocyte transmembrane sodium transport; and the glucose, plasma insulin, and C-peptide responses to an oral glucose tolerance test were investigated. Subjects with PFH had higher blood pressure, body weight, body mass index (BMI), waist/hip ratio (WHR), and abdominal sagittal diameter than subjects with NFH. Baseline blood glucose, plasma insulin, serum lipids, and transmembrane sodium transport did not differ between the two groups. Blood glucose levels at 90 and 120 minutes after oral glucose were significantly higher in subjects with PFH than in controls. Blood glucose adjusted for BMI and WHR at 90 minutes was significantly related to a PFH. Plasma insulin level at 90 minutes during the glucose load was significantly higher in subjects with PFH. In multivariate analysis, WHR was significantly related to baseline blood pressure, insulin, and cholesterol, whereas BMI was significantly associated with the insulin response to the oral glucose tolerance test. Transmembrane sodium transport was significantly related to blood pressure only. In conclusion, subjects with PFH are characterized by increased body weight and BMI, increased visceral fat accumulation, and an altered blood glucose response to an oral glucose load. It was also shown that WHR was related to blood pressure and that BMI was more related to cholesterol and response to glucose loading than a PFH was.