Food does not affect the pharmacokinetics of tesaglitazar, a novel dual peroxisome proliferator-activated receptor alpha/gamma agonist.

Tesaglitazar is a dual peroxisome proliferator-activated receptor (PPAR) alpha/gamma agonist in development to treat lipid and glucose abnormalities associated with type 2 diabetes. This study evaluated the effects of food on tesaglitazar pharmacokinetics. In an open, randomized, 2-way crossover study, 20 healthy men received tesaglitazar 1 mg during fasting and after a high-fat, high-calorie breakfast. Blood samples were taken to assess pharmacokinetic variables. Systemic exposure to tesaglitazar was unaffected by food intake. Estimated ratios were 0.99 (90% confidence interval [CI], 0.94-1.04) for fed/fasted area under plasma concentration-time curve and 0.82 (90% CI, 0.78-0.86) for fed/fasted maximum plasma concentration (C(max)). Mean C(max) was approximately 18% lower (0.41 [95% CI, 0.38-0.43] versus 0.50 [95% CI, 0.47-0.53] mumol/L), and median time to C(max) was increased (2.00 vs 0.75 h) in fed versus fasted state. The median difference of t(max) was 1.25 h (P = .0001, signed-rank test). Tesaglitazar was well tolerated. Tesaglitazar pharmacokinetics is unaffected by food intake, allowing once-daily administration of tesaglitazar with or without food in clinical practice.

Pharmacokinetics and metabolism of tesaglitazar, a novel dual-acting peroxisome proliferator-activated receptor alpha/gamma agonist, after a single oral and intravenous dose in humans.

The pharmacokinetics of tesaglitazar (GALIDA), a novel dual-acting peroxisome proliferator-activated receptor alpha and gamma agonist, were studied in eight healthy male subjects. The subjects initially received either a single oral or intravenous (i.v.) dose of 1 mg of [(14)C]tesaglitazar. After a washout period, they received 1 mg of nonlabeled tesaglitazar via the alternative administration route. Serial blood samples and complete urine and feces were collected until 336 h postdose. Tesaglitazar absorption was rapid, with maximum plasma concentration (C(max)) at approximately 1 h postdose, and the absolute bioavailability was approximately 100%, suggesting no, or negligible, first-pass metabolism. Mean plasma clearance was 0.16 l/h and the volume of distribution at steady state was 9.1 liters. After either route of administration, the plasma concentration-time profiles of radioactivity and tesaglitazar were virtually identical, indicating low systemic metabolite concentrations and formation rate limitation of metabolite elimination. The elimination half-life of radioactivity and tesaglitazar was approximately 45 h. Radioactivity recovery was complete in all subjects, with mean values of 99.9% (i.v.) and 99.6% (oral). Tesaglitazar was mainly metabolized before excretion, and most radioactivity (91%) was recovered in urine. Approximately 20% of the dose was recovered unchanged after either administration route, resulting in a renal clearance of 0.030 l/h. Most of the radioactivity in urine was identified as acyl glucuronide of tesaglitazar. Plasma protein binding of tesaglitazar was high ( approximately 99.9%), and the mean blood-plasma partitioning ratio was 0.66, suggesting low affinity for red blood cells. There was no indication of partial inversion of the (S)-enantiomer to the corresponding (R)-form. Tesaglitazar was well tolerated.

Beta1-adrenergic receptor gene polymorphisms and response to beta1-adrenergic receptor blockade in patients with essential hypertension.

BACKGROUND: Studies suggest that the Ser49Gly and Arg389Gly polymorphisms in the beta1-adrenergic receptor might be of functional importance for the cardiovascular system. Both have been associated with altered receptor activity in vitro, and with hypertension and cardiac failure in vivo. HYPOTHESIS: The aim of this study was to test whether these polymorphisms were associated with the change in heart rate or blood pressure in patients with essential hypertension and left ventricular (LV) hypertrophy treated with the beta1-adrenergic receptor blocker atenolol. METHODS: Blood pressure and heart rate were measured in 101 hypertensive patients with echocardiographically verified LV hypertrophy, randomized in a double-blind study to treatment with either the beta1-adrenergic receptor blocker atenolol or the angiotensin II type I receptor antagonist irbesartan. Changes in blood pressure and heart rate were evaluated after 12 weeks. Beta1-adrenergic receptor genotyping was performed using polymerase chain reaction and restriction fragment length polymorphism. RESULTS: We found no significant associations between the changes in the measured variables and either of the two polymorphisms. However, carriers of the 49Gly allele showed a tendency toward a greater reduction in heart rate compared with patients with the Ser/Ser49 genotype (p = 0.06). CONCLUSIONS: The Ser49Gly and Arg389Gly beta1-adrenergic receptor polymorphisms do not seem to exert a major effect on the changes in heart rate and blood pressure during 12 weeks of treatment with atenolol in patients with essential hypertension and LV hypertrophy.

A single nucleotide polymorphism in the promoter region of the osteoprotegerin gene is related to intima-media thickness of the carotid artery in hypertensive patients. The Swedish Irbesartan Left Ventricular Hypertrophy Investigation vs Atenolol (SILVHIA).

Osteoprotegerin (OPG) is a secreted member of the tumor necrosis factor receptor family, and in previous studies has been shown to regulate osteoclast activity and differentiation. Ablation of the OPG gene in mice results in calcification of the aorta and renal arteries. We have previously reported an association between a single nucleotide polymorphism in the promoter region of OPG and vascular morphology and function in healthy humans. The objective with this study was to confirm our previous results in a larger population, and in addition, to study subjects with hypertension. The OPG genotype was determined by restriction fragment length and the intima-media thickness (IMT) of the common carotid artery was measured by ultrasound in 100 patients with hypertension and left ventricular hypertrophy, and 75 healthy normotensive control subjects. In the hypertensive group subjects with the CC genotype (n=24) showed a significantly increased IMT compared to those with the TC (n=52, p=0.007) and TT (n=24, p=0.009) genotype, in the hypertensive group only (mean +/- SD for TT=0.88 +/- 0.21 mm, TC=0.90 +/- 0.16 mm, CC=1.05 +/- 0.31 mm). The allele distribution did not differ between hypertensive and control individuals. The present study confirms our previous finding and shows that polymorphism in the promoter region of OPG is associated with vascular morphology in hypertensive subjects.

Gender-specific association between preproendothelin-1 genotype and reduction of systolic blood pressure during antihypertensive treatment--results from the Swedish Irbesartan Left Ventricular Hypertrophy Investigation versus Atenolol (SILVHIA).

BACKGROUND: Studies suggest that endothelin-1 contributes to the pathogenesis of hypertension. A G5665T gene polymorphism of preproendothelin-1 has been shown to be associated with higher blood pressure in overweight patients. No study has yet determined the effect of this polymorphism on the change in blood pressure during antihypertensive treatment. HYPOTHESIS: This study aimed to determine this effect in hypertensive patients with left ventricular (LV) hypertrophy during antihypertensive treatment with either irbesartan or atenolol. METHODS: We determined the preproendothelin-1 genotype using minisequencing in 102 patients with essential hypertension and LV hypertrophy verified by echocardiography, randomized in a double-blind fashion to treatment with either the AT1-receptor antagonist irbesartan or the beta1-adrenoceptor antagonist atenolol. RESULTS: The change in systolic blood pressure (SBP) after 12 weeks of treatment was related to the preproendothelin-1 genotype in men; after adjustment for potential covariates (age, blood pressure, and LV mass index at study entry, dose of irbesartan/atenolol, and type of treatment), those carrying the T-allele responded on average with a more than two-fold greater reduction than those with the G/G genotype (-21.9 mmHg 13.9] vs. -8.9 [2.3], p = 0.007). No significant differences in blood pressure change between G/G and carriers of the T-allele were seen among women. CONCLUSIONS: Our finding suggests a gender-specific relationship between the G5665T preproendothelin-1 polymorphism and change in SBP in response to antihypertensive treatment with irbesartan or atenolol, suggesting the endothelin pathway to be a common mechanism included in the hypertensive action of the drugs.

Relationships between left ventricular mass and the renin-angiotensin system, catecholamines, insulin and leptin.

OBJECTIVES: Several neurohormonal systems have been suggested to stimulate myocardial cell growth, and thus take part in the development of left ventricular (LV) hypertrophy. We studied associations between LV mass and markers of the renin-angiotensin-aldosterone system (RAAS), the sympathetic nervous system, glucose homeostasis and leptin. DESIGN: A total of 115 hypertensive patients with LV hypertrophy and two age- and gender-matched control groups consisting of 38 hypertensive patients without LV hypertrophy and 38 normotensive subjects were included. We examined determinants of the RAAS, plasma levels and 24-h urinary excretions of noradrenaline and adrenaline, plasma proinsulin, insulin, glucose, leptin and LV mass by echocardiography. RESULTS: Plasma renin activity (PRA) and serum aldosterone were higher (both P < 0.001) in the LV hypertrophy group than in patients without LV hypertrophy and normotensive subjects (1.0 +/- 0.8, 0.2 +/- 0.2 and 0.2 +/- 0.2 ng mL(-1) h(-1), and 327 +/- 126, 269 +/- 146 and 221 +/- 80 pmol L(-1), respectively). PRA and aldosterone both related (P < 0.001) to LV mass index (r = 0.44 and 0.27, respectively). Catecholamine levels and excretions were similar in all three groups and did not relate to LV mass index. Proinsulin, insulin and leptin levels were all elevated in the hypertensive patients (P < 0.01), but proinsulin, insulin, insulin sensitivity (by the homeostasis model assessment) and leptin did not relate to LV geometry, when indexed for body size. CONCLUSIONS: Plasma renin activity and serum aldosterone levels are elevated in hypertensive LV hypertrophy and relate to LV mass index. In addition to blood pressure, activation of the RAAS may be an important nonhaemodynamic mechanism in the control of LV hypertrophy.

Angiotensin converting enzyme gene polymorphism predicts blood pressure response to angiotensin II receptor type 1 antagonist treatment in hypertensive patients.

OBJECTIVES: To determine whether polymorphisms in the renin-angiotensin system can predict blood pressure-lowering response to antihypertensive treatment; more specifically, in response to treatment with irbesartan or atenolol. DESIGN AND METHODS: Eighty-six patients with hypertension were randomized to double-blind treatment with either the angiotensin II type 1 receptor antagonist irbesartan or the beta1 adrenergic receptor blocker atenolol and followed for 3 months. We analysed angiotensinogen T174M and M235T, angiotensin converting enzyme (ACE) I/D and angiotensin II type 1 receptor A1166C polymorphisms and related them to blood pressure reduction. RESULTS: The mean reductions in blood pressure were similar for both treatments. In the irbesartan group, individuals homozygous for the ACE gene I allele showed a greater reduction in diastolic blood pressure, exceeding those with the D allele (-18 +/- 11 SD versus -7 +/- 10 mmHg, P = 0.0096). This was not the case during treatment with atenolol, and the interaction term between type of treatment and ACE II genotype was significant (P = 0.0176). The angiotensinogen and angiotensin II type 1 receptor polymorhisms were not related to the response to treatment. CONCLUSIONS: ACE genotyping predicted the blood pressure-lowering response to antihypertensive treatment with irbesartan but not atenolol. Thus, specific genotypes might predict the response to specific antihypertensive treatment.

Regression of left ventricular hypertrophy in human hypertension with irbesartan.

BACKGROUND: The Swedish irbesartan left ventricular hypertrophy investigation versus atenolol (SILVHIA). OBJECTIVE: Angiotensin II induces myocardial hypertrophy. We hypothesized that blockade of angiotensin II subtype 1 (AT1) receptors by the AT1-receptor antagonist irbesartan would reduce left ventricular mass (as measured by echocardiography) more than conventional treatment with a beta blocker. DESIGN AND METHODS: This double-blind study randomized 115 hypertensive men and women with left ventricular hypertrophy to receive either irbesartan 150 mg q.d. or atenolol 50 mg q.d. for 48 weeks. If diastolic blood pressure remained above 90 mmHg, doses were doubled, and additional medications (hydrochlorothiazide and felodipine) were prescribed as needed. Echocardiography was performed at weeks 0, 12, 24 and 48. RESULTS: Baseline mean blood pressure was 162/ 104 mmHg, and mean left ventricular mass index was 157 g/m2 for men and 133 g/m2 for women. Systolic and diastolic blood pressure reductions were similar in both treatment groups. Both irbesartan (P < 0.001) and atenolol (P< 0.001) progressively reduced left ventricular mass index, e.g. by 26 and 14 g/m2 (16 and 9%), respectively, at week 48, with a greater reduction in the irbesartan group (P = 0.024). The proportion of patients who attained a normalized left ventricular mass (i.e. < or = 131 g/m2 for men and < or = 100 g/m2 for women) tended to be greater with irbesartan (47 versus 32%, P = 0.108). CONCLUSIONS: Left ventricular mass was reduced more in the irbesartan group than in the atenolol group. These results suggest that blocking the action of angiotensin II at AT1-receptors may be an important mechanism, beyond that of lowering blood pressure, in the regulation of left ventricular mass and geometry in patients with hypertension.

Less difference between office and ambulatory blood pressure in women than in men both before and during antihypertensive treatment.

In 199 subjects (56% women) with a diastolic blood pressure (BP) of 95-115 mmHg, 5 mg of either amlodipine or felodipine extended release (ER) was given for 4 weeks following 4 weeks of placebo-treatment. BP was measured by conventional clinic BP technique and by 24-h ambulatory BP monitoring (Spacelab 90202/90207). Men and women had identical clinic BP at baseline and it was lowered equally much by 4 weeks of treatment (men: 158/101 and 147/93, women: 159/102 and 149/93 mmHg, respectively). However, ambulatory BP was higher in women than in men both before and after treatment (men: 145/91 and 134/85, women: 149/95 and 140/89 mmHg, respectively, p < 0.05 for both comparisons). The difference between clinic BP and daytime ambulatory BP was higher in men than in women (systolic men: 8.1 +/- 14, women: 3.7 +/- 15 mmHg, respectively, p = 0.04; diastolic men: 5.5 +/- 8.0, women: 2.1 +/- 8.3 mmHg, p = 0.004). The correlation between the treatment effect measured by ambulatory and clinic BP was poor (systolic r = 0.26, p < 0.0001; diastolic r = 0.17, p = 0.03) and was unaffected by exclusion of subjects with normal ambulatory BP. The poor correlation between treatment effects measured as clinic and ambulatory BP is intriguing, and suggests that using ambulatory BP instead of clinic BP for monitoring the treatment of hypertension could affect the clinical outcome.

Pitfalls in Doppler evaluation of diastolic function: insights from 3-dimensional magnetic resonance imaging.

Ultrasound-Doppler assessment of diastolic function is subject to velocity errors caused by angle sensitivity and a fixed location of the sample volume. We used 3-dimensional phase contrast magnetic resonance imaging (MRI) to evaluate these errors in 10 patients with hypertension and in 10 healthy volunteers. The single (Doppler) and triple (MRI) component velocity was measured at early (E) and late (A) inflow along Doppler-like sample lines or 3-dimensional particle traces generated from the MRI data. Doppler measurements underestimated MRI velocities by 9.4% +/- 8.6%; the effect on the E/A ratio was larger and more variable. Measuring early and late diastolic inflows from a single line demonstrated the error caused by their 3-dimensional spatial offset. Both errors were minimized by calculating the E/A ratio from maximal E and A values without constraint to a single line. Alignment and spatial offset are important sources of error in Doppler diastolic parameters. Improved accuracy may be achieved with the use of maximal E and A velocities from wherever they occur in the left ventricle.

Plasma levels of cyclic GMP and endothelin in postmenopausal women with unstable coronary artery disease.

Many women with typical anginal chest pain have normal coronary angiograms, which may be due to altered endothelial function. We evaluated the endothelial markers cyclic GMP (cGMP) and immunoreactive endothelin (ir-ET) regarding presence of coronary atherosclerosis in women with clinical signs of unstable coronary artery disease (CAD). Plasma levels of cGMP and ir-ET were determined in 118 patients and 84 controls. Ischaemia was evaluated at an exercise test. Of the patients 20% had normal vessels, 14% insignificant CAD and 66%, significant stenosis at coronary angiography. Mean (95% CI) concentration of cGMP (nmol/l) was higher in patients than in controls (5.05 (4.53; 5.58) vs. 3.79 (3.34; 4.23)). Separating patients according to daily intake of nitroglycerin, only patients with this medication had significantly higher cGMP level (5.73 (4.88; 6.58)), whereas the difference between those without (4.35 (3.76; 4.94)) and controls disappeared. Patients with ischaemia at exercise test had higher cGMP level than those without (6.01 (5.13; 6.88) vs. 4.30 (3.66; 4.94)), even after adjusting for nitroglycerin treatment. ir-ET (pmol/l) was lower in patients with normal vessels than patients with coronary atherosclerosis (0.83 (0.78; 0.88) vs. 0.98 (0.92; 1.04)) and than the control group (0.91 (0.87; 0.94)). The difference between the control group and patients with atherosclerosis was also significant. Patients with unstable CAD and long-term nitroglycerin treatment have increased cGMP level. Patients with exercise-induced ischaemia have higher cGMP level than those without, irrespective of nitroglycerin treatment, which may reflect a general compensatory mechanism. Patients with normal vessels have low level of ir-ET, indicating different mechanisms for ischaemia/angina in these patients compared with patients with atherosclerosis.

Effect of amlodipine versus felodipine extended release on 24-hour ambulatory blood pressure in hypertension.

Amlodipine and felodipine are calcium antagonists of the dihydropyridine type. The elimination half-life of amlodipine is longer than that of felodipine. To study whether the different elimination rates of the drugs were reflected in different duration of blood pressure (BP) control, we compared amlodipine and felodipine extended release (ER) by both conventional clinic BP 24 h after drug intake and 24 h ambulatory BP monitoring (ABPM), with special reference to nighttime and morning blood pressure. Two hundred and sixteen patients with primary hypertension (supine diastolic BP, 95 to 115 mm Hg) were randomized to receive amlodipine or felodipine ER in a multicenter study. The starting dose of both drugs was 5 mg. If the target clinic diastolic BP (90 mm Hg) had not been achieved after 4 weeks the dose was increased to 10 mg. Twenty-four-hour ABPM was performed with the subjects taking placebo medication before randomization and after 4 and 8 weeks undergoing active treatment. Significantly more patients responded after 4 weeks of treatment with amlodipine (50%) as compared with felodipine (33%) (P = .013). ABPM during daytime (07:00 to 23:00) was similar during both treatments, but nighttime systolic (P = .026) and diastolic (P = .019) BP was more effectively reduced by amlodipine than by felodipine. After 8 weeks 82% achieved the target pressure with amlodipine and 69% with felodipine (P = .036 for the difference). Amlodipine seems to be more effective than felodipine when the drugs are compared in the same dose, with regard to the effect on clinic BP 24 h after dosing and to ambulatory BP during the night. The longer elimination half-life of amlodipine as compared to felodipine is the probable reason for this finding.

Circulating plasma prekallikrein and tissue kallikrein in normotensive and hypertensive humans: effects of angiotensin II infusion.

Kinins lower blood pressure but the stimuli leading to kinin generation and their origin are less well known. We administered angiotensin II in graded infusion doses to patients with primary hypertension and normotensive controls to study the effects of on circulating kallikreins. Angiotensin II infusion did not significantly alter plasma prekallikrein or tissue kallikrein levels and the plasma levels and their changes did not correlate with blood pressure levels or changes. In the normotensive group prekallikrein levels and renin activity correlated negatively with urinary sodium and chloride excretion during basal conditions and partially during the infusion. U-tissue kallikrein concentration increased in the normotensive group. Thus, acute elevation of blood pressure induced by angiotensin II does not activate the circulating kallikrein-kinin systems. Data rather indicate that the circulating kallikrein-kinin systems may be related to alterations in volume and sodium balance and that these mechanisms may be altered in primary hypertension.

A population-based study of the white-coat blood pressure effect: positive correlation with plasma cortisol.

We aimed to study the white-coat effect (WCE) of clinic blood pressure (BP) and its relation to plasma cortisol, neuropeptide Y (NPY) and demographic variables. Henry et al. have earlier suggested two stress-reaction patterns. The "defeat reaction" mainly involves the cortisol-axis and the "fight-flight-response" is mediated by the sympathoadrenal-system. Ninety-one men and 88 women 20-70 years of age, randomly selected from the population were recruited in this cross-sectional study. Clinic BP, plasma cortisol and plasma NPY (both analysed by radio-immunoassay) were obtained at 0800 h and 24h ambulatory BP (ABP) was performed. WCE was defined as supine clinic BP - mean daytime ABP. Cortisol correlated to the systolic WCE in the total material* (r = 0.22, p = 0.005) and in men 45-70 years of age (r = 0.45, p = 0.002, n = 47) and to diastolic WCE in women 45-70 years of age* (r = 0.37, p = 0.02, n = 38). (*women treated with oestrogens, or being pregnant, excluded, n = 21). Only in women did NPY correlate weakly to the systolic WCE (r = 0.22, p = 0.044). Subjects with one or more first degree hypertensive relative had a more marked systolic WCE than those without (-0.02 +/- 10 mmHg and -4.1 +/- 9.3 mmHg, respectively, p = 0.01). In conclusion cortisol correlated stronger to the WCE than did NPY. This would suggest the WCE to be a defeat reaction rather than a fight-flight-response.

Serum leptin concentrations in a normal population and in GH deficiency: negative correlation with testosterone in men and effects of GH treatment.

OBJECTIVE: To study relationships between leptin and factors regulating body composition as well as metabolic risk factors. Furthermore, to study the effects of GH on leptin. DESIGN: Cross-sectional and population-based. Regarding the effects of GH, prospective and interventional. PATIENTS: One hundred and eleven women and 107 men, 20-70 years old, randomly selected from the population registry in the community of Linköping, Sweden. Ten GH-deficient subjects were given GH until normalization of IGF-I levels. MEASUREMENTS: Venous blood was drawn in the fasting state. Serum leptin and hormones were analysed by immunoassay. RESULTS: In the population sample the natural logarithm of leptin (in(leptin)) correlated with body mass index (BMI) (men, r = 0.67), P < 0.0001; women, r = 0.71, P < 0.0001). The median value of leptin was 4.6 micrograms/l in men and 12.3 micrograms/l in women (P < 0.0001). Levels of in(leptin) did not correlate with plasma neuropeptide Y (men, P = 0.13; women, P = 0.35). In men only there was an inverse relationship between in(leptin) and testosterone (r = -0.46, P < 0.0001, after correction for BMI standardized r = -0.26, P = 0.03) as well as IGF-I (r = -0.20, P = 0.048). Although BMI was similar, smoking men had higher leptin levels than non-smoking men (median, 6.6 and 4.2 micrograms/l, respectively; Mann-Whitney; P = 0.006). In the GH-deficient subjects leptin levels were elevated and, although GH treatment did not change BMI, leptin levels decreased (median before GH, 21 micrograms/l and after 15 micrograms/l, respectively; P = 0.017). CONCLUSION: Serum leptin concentration is closely associated with BMI in the population with a gender difference in absolute levels and a strong negative correlation with testosterone in men. Serum leptin is elevated in GH deficiency and lowered by GH substitution.

Circulating kallikreins in normotensive and hypertensive humans: effects of mineralocorticoid administration.

The aim of the study was to evaluate if short-term mineralocorticoid administration activates the circulating kallikrein-kinin systems in normotensive humans and patients with hypertension. Fludrocortisone was given daily for 1 week and circulating components of the plasma and tissue kallikrein-kinin systems and renin-angiotensin-aldosterone system were measured repeatedly. Fludrocortisone increased blood pressure in the normotensive group. A significant reduction in circulating pre-kallikrein and increase in tissue kallikrein occurred only in the normotensive group. Changes in blood pressure in the normotensive group correlated negatively with changes in plasma pre-kallikrein and positively with changes in circulating tissue kallikrein. In the hypertensive group the correlation with pre-kallikrein was non-significant and with tissue kallikrein negative. We conclude that short-term administration of fludrocortisone in moderate doses to normotensive humans induces changes compatible with increased activity in the circulating plasma and tissue kallikrein-kinin systems and that this activation may be abnormal in subjects with primary hypertension.

Serum angiotensin-converting enzyme activity correlates positively with plasma angiotensin II: a population-based study of ambulatory blood pressure and the renin-angiotensin system.

A population-based study was performed in order to study the interrelationships of the circulating components of the renin-angiotensin system during basal conditions and their relations to blood pressure (BP), age and gender. One hundred and four women and 95 men, 16-70 years old, evenly age distributed and randomly selected from the population of Linköping, Sweden, participated. Venous blood was drawn at 08.00 hours and ambulatory BP recording was then performed. Serum angiotensin-converting enzyme (ACE) activity correlated with plasma angiotensin II (r = 0.20, P = 0.004), but when calculated separately according to gender, the correlation remained significant only in men (r = 0.33, P = 0.001). Plasma renin activity (PRA) correlated negatively with age (r = -0.30, P < 0.0001), but immunoreactive active renin (IRR) and angiotensin II did not. PRA and IRR correlated negatively with BP in women but correlations disappeared after age adjustment. The 23 women on oestrogen medication did not differ from the remaining 81 with respect to age (P = 0.5), IRR (P = 0.96) or angiotensin II (P = 0.4) levels, but PRA was higher (2.2 +/- 1.4 ng Ang l/ml/h and 1.5 +/- 0.9 ng Ang l/ml/h, respectively, P = 0.004). PRA (r = 0.38, P < 0.0001) and IRR (r = 0.49, P < 0.0001) correlated positively with the levels of angiotensin II. In conclusion the fact that PRA, but not IRR, declined with age and was higher among oestrogen-treated women, although angiotensin II was unaffected suggests IRR to be a more robust marker of angiotensin II levels than is PRA in a population-based setting. ACE correlates positively with angiotensin II in men.

Circulating kallikreins during sodium chloride infusion in normal and hypertensive humans.

The stimuli generating kinins participating in blood pressure, volume and sodium homeostasis and their origin are not fully known. We studied the effects of a combined sodium and volume load on circulating plasma and tissue kallikreins. Normal saline (2000 ml) was infused over 4 h in 14 subjects with primary hypertension and 15 age- and sex-matched normotensive control subjects. The infusion increased blood pressure slightly in both groups. Plasma prekallikrein levels fell in both groups (normotensives: 98 +/- 4 to 87 +/- 5%, p = 0.002; hypertensives: 106 +/- 5 to 94 +/- 6%, p = 0.003), but more rapidly in normotensives. Circulating tissue kallikrein did not change significantly in the normotensive group but was reduced in the hypertensive group. Sodium excretion during the infusion correlated negatively with changes in plasma prekallikrein and positively with plasma levels of tissue kallikrein in the normotensive group only. Urinary tissue kallikrein excretion during the infusion increased significantly only in the normotensive group. The levels or changes of circulating prekallikrein and tissue kallikrein were not related to the levels or changes in blood pressure in any of the groups. In the hypertensive group there was a negative correlation between blood pressure changes and urinary sodium and tissue kallikrein excretion. Thus, in normotensive subjects an acute sodium and volume load appears to activate the plasma kallikrein system and the activation correlates with sodium excretion. There are subtle differences in subjects with primary hypertension. The relevance of these differences with respect to the pathogenesis of primary hypertension remains to be evaluated.

Twenty-four hour ambulatory blood pressure in the population.

OBJECTIVES: To establish a population-based 24-h ambulatory blood pressure (ABP) reference material with day/night mean BP calculated by standardized and true bedtimes. DESIGN: A cross-sectional study of 200 randomly selected subjects (20 men and 20 women in each 10-year age interval 20-70 years) in Linköping, Sweden. SETTING: University Hospital of Linköping, Sweden. RESULTS: Participation rate was 67%. Mean supine clinic BP (CBP) and 24-h-ABP values for the whole material were 123 +/- 13/79 +/- 8 mmHg and 120 +/- 10/73 +/- 7 mmHg, respectively. White coat BP phenomenon increased with age (systolic CBP/ABP ratio versus age, r = 0.35, P < 0.0001). Seventeen participants had a night/day mean arterial blood pressure ratio > 0.9 (non-dipper) when calculated from their own time-notations. If standardized day (06.00-23.00) and night (23.00-06.00) limits were used, 24 subjects were non-dippers. Of these, only eight were 'true'. 'True' non-dippers had a similar day-time mean arterial ABP as 'true' dippers (92.4 +/- 11 mmHg versus 91.9 +/- 13 mmHg, P = 0.92) while night-time BP was higher (89.9 +/- 13 mmHg versus 74.1 +/- 7 mmHg, P < 0.0001). CONCLUSION: Population-based ABP reference values have been defined. We found 9% non-dippers and that standardized day/night-time limits may lead to misclassification. This could be due to gender- and age-differences in sleeping habits, which was also shown in this study. The frequency of white coat BP phenomenon increases with age.

A population study of plasma neuropeptide Y: correlations with components of the metabolic syndrome.

UNLABELLED: To study the relations between neuropeptide Y (NPY) and age, gender, blood pressure (BP) and risk factors for cardiovascular disease and the renin angiotensin system, we performed a population-based study through random selection of 220 subjects (49% men). Subjects on antihypertensive therapy were excluded and participation rate was 67%. Venous blood was drawn at 08.00 h in the fasting state and a Spacelab 90202/90207 ambulatory BP device was then fitted. Plasma NPY levels were normally distributed and the mean level was 144 +/- 17 pmol/L (mean +/- SD). There was a trend towards higher levels in women than in men (147 +/- 17 pmol/L and 142 +/- 17 pmol/L, respectively, p = 0.053). No correlations were found between NPY and ambulatory BP or clinic BP in either gender. Angiotensin II correlated positively with NPY in men but not in women (r = 0.27, p = 0.007). There were no correlations between NPY and body mass index, waist/hip ratio, BP or C-peptide in either gender. Total cholesterol (r = 0.39, p < 0.0001) and LDL-cholesterol (r = 0.35, p = 0.0001) were positively correlated with NPY in women only. The correlation remained in multiple regression analysis with plasma total or LDL- cholesterol as second independent variable to age, and NPY as dependent variable (total cholesterol: standardised r = 0.43, p = 0.0002, LDL-cholesterol: standardised r = 0.34, p = 0.002, respectively). CONCLUSION: The positive correlation between LDL-cholesterol and NPY in women, independent of age, and components of the metabolic syndrome, makes it a possible gender-specific cardiovascular riskmarker.