Pioglitazone decreases carotid intima-media thickness independently of glycemic control in patients with type 2 diabetes mellitus: results from a controlled randomized study.

BACKGROUND: Patients with type 2 diabetes mellitus are at high risk of cardiovascular disease. Carotid intima-media thickness (IMT) is a strong predictor of myocardial infarction and stroke. METHODS AND RESULTS: We compared the effects of pioglitazone-based therapy (45 mg/d) and glimepiride-based treatment (2.7+/-1.6 mg/d) for 12 and 24 weeks on metabolic control (HbA1c), insulin resistance (homeostasis model assessment), and carotid IMT (B-mode ultrasonography) in a randomized controlled study in 173 orally treated patients with type 2 diabetes (66 women, 107 men; mean+/-SD age, 62.6+/-7.9 years; body mass index, 31.8+/-4.6 kg/m2; HbA1c, 7.5+/-0.9%). Treatment was generally well tolerated in both groups. Despite similar improvements in metabolic control (HbA1c) after 24 weeks (-0.8+/-0.9% [pioglitazone] versus -0.6+/-0.8% [glimepiride]; P=NS), carotid IMT was reduced only in the pioglitazone group after 12 weeks (-0.033+/-0.052 versus -0.002+/-0.047 mm [glimepiride]; P<0.01 between groups) and 24 weeks (-0.054+/-0.059 versus -0.011+/-0.058 mm [glimepiride]; P<0.005 between groups). Insulin resistance was also improved only in the pioglitazone group (homeostasis model assessment, -2.2+/-3.4 versus -0.3+/-3.3; P<0.0001 between groups). Reduction of IMT correlated with improvement in insulin resistance (r=0.29, P<0.0005) and was independent of improvement in glycemic control (r=0.03, P=0.68). CONCLUSIONS: We found a substantial regression of carotid IMT, independent of improved glycemic control, after 12 and 24 weeks of pioglitazone treatment. This finding may have important prognostic implications for patients with type 2 diabetes mellitus.

Endothelin-1 plus oxidized low-density lipoprotein, but neither alone, increase human monocyte adhesion to endothelial cells.

Endothelin-1 is a potent vasoconstrictor and mitogenic peptide that is implicated in the atherosclerosis of apolipoprotein E-deficient mice and may promote atherogenesis in humans. We hypothesized that endothelin-1 might promote the adhesion of monocytes to endothelial cells, a key early event in atherosclerosis. We investigated the adhesion of primary human monocytes (isolated by elutriation) to human umbilical vein endothelial cell cultures after incubation with endothelin-1 (0.1 and 0.01 nM; approximately physiological concentrations), copper-oxidized low-density lipoprotein (LDL) (0.1 mg/ml) and a combination of the two. After a 4 h incubation with 0.1 or 0.01 nM endothelin-1 combined with oxidized LDL, adhesion was increased to 120+/-4% (P<0.001 compared with control) and 118+/-4% (P<0.002) respectively, whereas neither substance alone increased adhesion (92-104% of control values; not significant). Neither endothelin receptor A blockade nor co-incubation with anti-fibronectin antibody inhibited the pro-adhesive effects of endothelin-1 plus oxidized LDL (115+/-7% and 115+/-3% of control compared with 120+/-4% respectively; not significant). Endothelial cell expression of intercellular adhesion molecule-1, vascular adhesion molecule-1 and E-selectin were unchanged throughout the experiment. Therefore physiological concentrations of endothelin-1 and oxidized LDL may act synergistically to increase the adhesion of human monocytes to endothelial cells, contributing in part to the observed pro-atherogenic effects of endothelin-1.

Impaired sodium excretion during mental stress in mild essential hypertension.

In hypertensive rats, environmental stress causes sodium retention by an exaggerated increase in renal sympathetic nerve activity, which is modulated by angiotensin II. We tested whether similar effects can be observed in humans. In 66 normotensive subjects (half of them with a family history of hypertension) and 36 subjects with mild essential hypertension, urinary sodium excretion and renal hemodynamics were examined at rest and during mental stress treated either with placebo or ACE inhibition in a double-blind, randomized, cross-over design. Despite a marked increase in glomerular filtration rate in response to mental stress (Deltaglomerular filtration rate, 4.3+/-7.7 mL/min in normotensives without versus 5.6+/-8.4 mL/min in normotensives with a family history versus 10.1+/-5.7 mL/min in patients with mild essential hypertension; P:<0.002), the increase in urinary sodium excretion was blunted in patients with mild essential hypertension (Deltaurinary sodium excretion, 0.12+/-0.17 mmol/min versus 0.10+/-0.14 mmol/min versus 0.05+/-0.14 mmol/min; P:<0.05). ACE inhibition corrected the natriuretic response to mental stress in subjects with mild essential hypertension (Deltaurinary sodium excretion, 0.05+/-0.14 mmol/min with placebo versus 0.13+/-0.19 mmol/min with ACE inhibition; P:<0.01); thus, after ACE inhibition, urinary sodium excretion increased similarly in all 3 groups. In conclusion, impaired sodium excretion occurs during mental stress in human essential hypertension but not in subjects with positive family history of hypertension. This abnormality in sodium handling during activation of the sympathetic nervous system appears to be mediated by angiotensin II.

Enhanced antinatriuresis in response to angiotensin II in essential hypertension.

Angiotensin II regulates sodium homeostasis by modulating aldosterone secretion, renal vascular response, and tubular sodium reabsorption. We hypothesized that the antinatriuretic response to angiotensin II is enhanced in human essential hypertension. We therefore studied 48 white men with essential hypertension (defined by ambulatory blood pressure measurement) and 72 normotensive white control persons, and measured mean arterial pressure, sodium excretion, renal plasma flow, glomerular filtration rate, and aldosterone secretion in response to angiotensin II infusion (0.5 and 3.0 ng/kg/min). Hypertensive subjects exhibited a greater increase of mean arterial pressure (16.7+/-8.2 mm Hg v 13.4+/-7.1 mm Hg in normotensives, P < .05) and a greater decrease of renal plasma flow (-151.5+/-73.9 mL/ min v -112.6+/-68.0 mL/min in controls, P < .01) when 3.0 ng/kg/min angiotensin II was infused. The increase of glomerular filtration rate and serum aldosterone concentration was similar in both groups. Sodium excretion in response to 3.0 ng/kg/min angiotensin II was diminished in both groups (P < .01). However, the decrease in sodium excretion was more pronounced in hypertensives than in normotensives (-0.18+/-0.2 mmol/min v -0.09+/-0.2 mmol/min, P < .05), even if baseline mean arterial pressure and body mass index were taken into account (P < .05). We conclude that increased sodium retention in response to angiotensin II exists in subjects with essential hypertension, which is unrelated to changes in glomerular filtration rate and aldosterone concentration. Our data suggest a hyperresponsiveness to angiotensin II in essential hypertension that could lead to increased sodium retention.

1166 A/C polymorphism of the angiotensin II type 1 receptor gene and the response to short-term infusion of angiotensin II.

BACKGROUND: Previous studies reported an association of the 1166 A/C polymorphism of the angiotensin II (Ang II) type 1 receptor gene with high blood pressure and cardiovascular disease. We tested the hypothesis that this polymorphism affects the blood-pressure, renal hemodynamic, and aldosterone response to infused Ang II. METHODS AND RESULTS: Young, male, white volunteers (n = 116) with normal (n = 65) or mildly elevated (n = 51) blood pressure on a high salt intake were genotyped for the 1166 A/C polymorphism. Two doses of Ang II (0.5 and 3 ng x kg(-1) x min(-1) over 30 minutes each) increased blood pressure, plasma aldosterone, glomerular filtration rate, and filtration fraction and decreased renal blood flow. The blood-pressure, renal hemodynamic, and aldosterone responses were not significantly different between subjects homozygous for the A allele (n = 56) and heterozygous subjects (n = 47) or subjects homozygous for the C allele (n = 13). Comparison of A allele homozygotes with all C allele carriers pooled (n = 60) or restriction of the analysis to normotensive volunteers also revealed no significant differences between genotypes. CONCLUSIONS: The 1166 C variant of the Ang II type 1 receptor does not lead to a greater blood-pressure, aldosterone, or renal vascular response to infused Ang II in young, male, white subjects. We conclude that the 1166 A/C polymorphism does not have a major effect on these actions of Ang II.

Hyper-responsiveness to angiotensin II is related to cardiac structural adaptation in hypertensive subjects.

BACKGROUND: Angiotensin II has been found to be a growth stimulating factor for myocardial cells. In humans, angiotensin II infusion causes vasoconstriction in systemic and renal vasculature and leads to aldosterone secretion. Our hypothesis was that hyper-responsiveness to angiotensin II is related to left ventricular mass in human essential hypertension. METHODS AND RESULTS: In 30 normotensive individuals and 30 subjects with mild essential hypertension (white men, mean age 26+/-3 years), the responsiveness to angiotensin II was assessed by measuring changes in mean arterial pressure, renal blood flow, glomerular filtration rate and aldosterone secretion in response to i.v. angiotensin II infusion (0.5 and 3.0 ng/kg per min). The provoked changes to angiotensin II infusion were similar in the normotensive and hypertensive group with the exception of an exaggerated increase in mean arterial pressure in hypertensives (14+/-5 versus 10+/-5 mm Hg, P<0.001 at 3.0 ng/kg per min angiotensin II). The increase in mean arterial pressure was correlated with left ventricular mass in hypertensive subjects (angiotensin II 0.5 ng/kg per min: r = 0.49, P<0.005; angiotensin II 3.0 ng/kg per min: r = 0.35, P<0.05); no such correlation was found in the normotensive group. After taking into account baseline mean arterial pressure and body mass index, the increase in mean arterial pressure to angiotensin II 0.5 ng/kg per min was still correlated with left ventricular mass (partial r = 0.50, P<0.01). Similarly, the change of glomerular filtration rate but not of renal blood flow in response to angiotensin II 0.5 ng/kg per min was correlated with left ventricular mass, (r = 0.42, P<0.02) in the hypertensive group but not in the normotensive one. This relationship remained significant even after taking baseline glomerular filtration rate, mean arterial pressure and body mass index into account (partial r = 0.43, P<0.05). CONCLUSION: Hyper-responsiveness to angiotensin II is related to an increased left ventricular mass in hypertensive subjects independent of blood pressure.

Impact of dietary sodium intake on left ventricular diastolic filling in early essential hypertension.

AIMS: Dietary sodium intake modulates left ventricular hypertrophy in established essential hypertension independent of blood pressure level. We conducted this study to elucidate the relationship between sodium intake and left ventricular structural or functional changes in early essential hypertension. METHODS: Forty-four young male patients (age 25.9 +/- 2.6 years) with mild essential hypertension that had never been treated and 45 normotensive male control subjects of similar age were examined. Dietary sodium intake was measured from 24 h urinary sodium excretion, blood pressure from 24 h ambulatory monitoring (SpaceLabs 90207), left ventricular structure from 2-D guided M-mode echocardiography, and diastolic filling of the left ventricle (as the main compound of diastolic function in a young population) by pulse-wave Doppler sonography. RESULTS: In hypertensive patients, daily sodium excretion correlated with the ratio of late (A) to early (E) maximum velocity (A/E; r = + 0.27, P = 0.07), velocity time integrals (A/E; r = + 0.54, P < 0.001) as well as atrial contribution, as a percent of left ventricular filling (VH ATCO; r = + 0.52, P < 0.001) independent of heart rate, whereas the opposite correlations were observed in normotensive (all P < 0.001). Stepwise multiple regression analysis confirmed these results. Sodium excretion emerged as the strongest independent determinant of impaired diastolic filling in hypertensive patients (velocity time integrals A/E: R(2) = 0.49, beta = 0.57, P = 0.0001; VH ATCO: R(2) = 0.48, beta = + 0.56, P < 0.0001; Vmax A/E: ns). In normotensive subjects, sodium excretion was a similar strong, but inverse determinant of diastolic filling (velocity time integrals A/E: R(2) = 0.40, beta = -0.43, P = 0.0028). Heart rate was a strong determinant of diastolic filling in hypertensive patients (beta = +0.55, P = 0.0002) and in normotensive subjects (beta = + 0.34, P = 0.011). Left ventricular mass and end-diastolic volume index were not related to diastolic filling in either group. CONCLUSION: In early essential hypertension, sodium excretion is correlated with impaired left ventricular diastolic filling independent of left ventricular mass. The renin-angiotensin-aldosterone-aldosterone system might be a mediator of the observed correlation.

Inadequate suppression of angiotensin II modulates left ventricular structure in humans.

BACKGROUND: In a previous study we found that high angiotensin II levels in relation to the corresponding urinary sodium excretion aggravate left ventricular hypertrophy in hypertensive patients. To analyze whether a dysregulation of the renin angiotensin aldosterone system determines left ventricular structure in young individuals, we examined whether the response of angiotensin II after increasing salt intake is related to left ventricular structure. METHODS: In 51 young, male Caucasians with normal or mildly elevated blood pressure, left ventricular structure, 24-hour ambulatory blood pressure and dietary sodium intake (as estimated by 24-hour sodium excretion) were determined in parallel with plasma renin activity, angiotensin II, and aldosterone concentrations. Angiotensin II concentration and 24-hour sodium excretion were measured twice: firstly on a normal Bavarian diet and secondly at high salt intake to determine the resulting suppression of the renin-angiotensin-aldosterone system. RESULTS: Body mass index (r = 0.42, p < 0.001) and both systolic (r = 0.28, p < 0.05) and diastolic (r = 0.25, p < 0.05) 24-hour ambulatory blood pressure correlated with left ventricular mass. No direct relationship was found between left ventricular structure and baseline angiotensin II concentration. The lower the physiological decrease of angiotensin II after high oral salt intake, i.e. the higher the angiotensin II level after salt intake remained, the greater was left ventricular mass (r = 0.38; p < 0.006) even after taking 24-hour ambulatory blood pressure into account (partial correlation; r = 0.43, p < 0.005). Consistently, angiotensin II concentration at high salt intake correlated with left ventricular mass independently of ambulatory blood pressure (partial correlation: r = 0.29, p < 0.05). Subgroup analysis revealed that the increase in sodium excretion at high salt intake was related to the decrease in angiotensin II levels in normotensive (r = -0.43, p < 0.05), but not in hypertensive subjects (r = 0.16, n.s.). The changes in angiotensin II concentration at high salt intake were related to left ventricular mass in hypertensive (r = 0.43, p < 0.02), but not in normotensive individuals (r = 0.21, n.s.). CONCLUSION: Our finding that angiotensin II concentration at high salt intake correlated with left ventricular mass independently of ambulatory blood pressure suggests that inadequate suppression of angiotensin II after high salt intake contributes to left ventricular hypertrophy already in young hypertensive individuals independently of blood pressure.

Does lipoprotein(a) impair endothelial function?

OBJECTIVES: This study was undertaken to test the hypothesis that lipoprotein(a) [Lp(a)] impairs endothelial function. BACKGROUND: Elevated Lp(a) plasma levels have been demonstrated to be associated with an increased risk of coronary heart disease. In atherosclerosis, endothelial dysfunction is known to be an early indicator of vascular changes. However, the effect of Lp(a) on nitric oxide (NO)-dependent vasodilator response has not yet been determined. We therefore examined the influence of Lp(a) on basal and stimulated NO-mediated vasodilator response in the forearm vascular bed. METHODS: Strain gauge plethysmography was used to measure changes in forearm blood flow produced by intraarterial infusion of increasing doses of acetylcholine (3, 12, 24 and 48 microg/min), sodium nitroprusside (200, 800 and 3,200 ng/min) and N-monomethyl L-arginine (L-NMMA) (1, 2 and 4 micromol/min) in 57 white subjects (mean age +/- SD 37 +/- 14 years). Lp(a) plasma concentrations were determined by rocket immunoelectrophoresis. RESULTS: Endothelium-dependent vasodilation tested by intraarterial acetylcholine and endothelium-independent vascular relaxation tested by intraarterial sodium nitroprusside were not correlated with Lp(a). Similarly, no significant differences in forearm blood flow changes were observed when patients were classified into tertiles according to their individual Lp(a) concentration. In contrast, changes in forearm blood flow after intraarterial L-NMMA indicating basal production and release of NO differed significantly among tertiles. Patients in the highest Lp(a) tertile (49.2 +/- 20.3 mg/dl) had a much greater vasoconstrictive response to L-NMMA than patients in the lowest Lp(a) tertile (4.8 +/- 2.5 mg/dl): 2 micromol/min of L-NMMA, -23.6 +/- 22.5% vs. -10.4 +/- 9.1% (p < 0.02); 4 micromol/min of L-NMMA, -27.8 +/- 10.3% vs. -17.6 +/- 9.9% (p < 0.03). Lp(a) plasma level consistently correlated negatively with the forearm blood flow responses to 4 micromol/min of intraarterial L-NMMA (r = -0.38, p < 0.01). Multiple stepwise regression analysis of variables, including total and high and low density lipoprotein cholesterol, further confirmed that plasma Lp(a) remained a significant independent determinant of forearm blood flow changes in response to L-NMMA (p < 0.02). CONCLUSIONS: The endothelium-dependent vasoconstrictive response to L-NMMA was enhanced in subjects with relatively high Lp(a) plasma levels, suggesting an increased basal production and release of NO. This response seemed to reflect a compensatory mechanism of the endothelium to yet unknown Lp(a)-induced atherosclerotic effects.

Impact of alpha- versus beta-blockers on hypertensive target organ damage: results of a double-blind, randomized, controlled clinical trial.

In hypertensive disease, the extent of target organ damage determines the prognosis. We conducted a 6-month, double-blind randomized study to compare the effects of an alpha1-adrenoreceptor blocker (bunazosin) with those of a beta1-adrenoreceptor blocker (metoprolol) on early hypertensive target organ damage at a similar level of blood pressure reduction. The study consisted of 43 patients (29 men and 14 women) of varying ages (mean age 52 +/- 9 years) with essential hypertension World Health Organization stage I-II. Both the alpha- and the beta-blocker lowered blood pressure to a similar extent measured by 24-h blood pressure monitoring. The left ventricular mass was comparably reduced in both cohorts (alpha-blocker 284 +/- 80 v 259 +/- 67 g, P < .05, beta-blocker 282 +/- 74 v 254 +/- 70 g, P < .05). Treatment with the alpha-blocker led to reduced total peripheral resistance (22.9 +/- 8.0 v 19.9 +/- 5.3 U, P < .05), whereas therapy with the beta-blocker resulted in an elevated total peripheral resistance (25.5 +/- 8.4 v 28.5 +/- 9.3 U, P < .10; P < .05 for the difference in both groups). Renal plasma flow remained constant in the alpha-blocker treated group but decreased in the beta-blocker treated group (508 +/- 141 v 477 +/- 134 mL/min/1.73 m2, P < .05). Glomerular filtration rate as measured by inulin clearance tended to increase after treatment with the alpha-blocker (112 +/- 20 v 115 +/- 18 mL/min/1.73 m2, P < .10) in accordance with a decrease of serum creatinine (1.00 +/- 0.14 v 0.93 +/- 0.12 mg/dL, P < .001). Plasma cholesterol and LDL cholesterol was lowered after treatment with the alpha-blocker (238 +/- 48 v 312 +/- 37 mg/dL; P < .001, and 153 +/- 32 v 130 +/- 25 mg/dL; P < .05) while remaining unchanged in group treated with the beta-blocker. Left ventricular hypertrophy was similarily reduced with alpha- and with beta-blockade at a comparable reduction of 24-h blood pressure. Alpha-blockers effected a more favorable renal and systemic hemodynamic profile than beta-blockers, but only long-term prospective studies will answer the question whether these hemodynamic effects result into a better cardiovascular prognosis.

Is endogenous erythropoietin a pathogenetic factor in the development of essential hypertension?

BACKGROUND: Recent experimental studies have found that erythropoietin elicits vasoconstriction and proliferation of endothelial cells. We conducted the following study to assess the possible interactions between endogenous erythropoietin, systemic and renal haemodynamics at different stages of essential hypertension. METHODS: We examined 47 patients with borderline essential hypertension (age 26 +/- 3 years) and 49 patients with established essential hypertension WHO stage I-II (age 52 +/- 10 years), and compared them to 42 normotensive individuals (age 26 +/- 3 years). The concentration of erythropoietin (radioimmunoassay), 24-h ambulatory blood pressure (Spacelab 90207), systemic haemodynamics (Doppler sonography) and renal haemodynamics (para-aminohippuric acid and inulin clearance) were determined. RESULTS: Erythropoietin was within normal range and similar among the three groups. In patients with established essential hypertension, a close correlation was found between erythropoietin and systolic (r = 0.45, P < 0.002) and diastolic (r = 0.51, P < 0.001) ambulatory blood pressure. In contrast, ambulatory blood pressure was not correlated with erythropoietin in subjects with borderline hypertension. Total peripheral resistance (r = 0.41, P < 0.02) was linked to erythropoietin in established but not in borderline hypertension. However, erythropoietin was inversely correlated with renal plasma flow in both established and borderline hypertension (r = -0.33, P < 0.05, and r = -0.34, P < 0.05 respectively). In normotensive subjects, in contrast, erythropoietin was not correlated with any of the determined variables. In neither group erythropoietin was linked to the haematocrit or hemoglobin concentration. CONCLUSION: The correlation between erythropoietin and renal vascular changes which is already present in borderline hypertension and is confirmed in established hypertension indicates an involvement of erythropoietin in the development of essential hypertension. The presence of normal concentrations of endogenous erythropoietin in all groups suggests a dysregulation of erythropoietin in patients with essential hypertension as the pathophysiological link between erythropoietin and vascular changes.

Endogenous erythropoietin correlates with blood pressure in essential hypertension.

Patients on maintenance hemodialysis with a family history of essential hypertension are at higher risk for increased arterial blood pressure when treated with erythropoietin than patients without family history. This study was performed to elucidate the role of endogenous erythropoietin in essential hypertension. We conducted a study in 42 untreated patients (mean age, 51 +/- 9 years) with essential hypertension World Health Organization stages I or II. Ambulatory 24-hour blood pressure (Spacelab 90207), cardiac output (2D guided M-mode echocardiography and CW Doppler sonography), renal hemodynamics (para-aminohippurate and inulin clearance), and endogenous erythropoietin (radioimmunoassay) together with erythrocyte count, hemoglobin, and hematocrit were measured in parallel. Mean 24-hour systolic blood pressure was 145 +/- 13 mm Hg, and mean diastolic blood pressure was 93 +/- 8 mm Hg. The average erythropoietin concentration was 15.3 +/- 3.7 mU/mL and within the normal range. We found that the higher erythropoietin concentrations, the more elevated was both 24-hour ambulatory systolic (r = 0.51, P < 0.005) and diastolic blood pressure (r = 0.49, P < 0.005). Also, the concentration of endogenous erythropoietin was correlated with total peripheral resistance as noninvasively determined by echocardiographic and Doppler sonographic measurements (r = 0.40, P < 0.02 and r = 0.49, P < 0.02, respectively). With increasing erythropoietin concentrations, renal plasma flow and renal blood flow were found to be progressively reduced (r = -0.32, P < 0.05 and r = -0.35, P < 0.05, respectively) and renal vascular resistance increased (r = 0.41, P < 0.01). Neither hematocrit nor hemoglobin nor erythrocyte count were related to endogenous erythropoietin concentrations. In human essential hypertension, the level of arterial blood pressure is related to endogenous erythropoietin, which is hemodynamically mediated by an increase of total peripheral resistance. Because erythropoietin has shown proliferative and vasoconstricting effects on the endothelium in experimental studies, we suggest that endogenous erythropoietin might be an aggravating or even a promoting factor in the pathogenesis of essential hypertension.

Antihypertensive efficacy and orthostatic tolerance of bunazosin vs nitrendipine: a multicentre double-blind randomized controlled study.

A multicentre double-blind randomized controlled study was conducted in 358 patients with mild to moderate essential hypertension. The goal was to compare the antihypertensive efficacy, tolerability, and in particular postural hypotension of the alpha 1-adrenoreceptor blocker bunazosin with the calcium channel blocker nitrendipine. Both treatment groups had comparable baseline blood pressure (BP) values, namely diastolic BP (DBP) of 103.8 +/- 5.6 mm Hg in the bunazosin group, and 103.4 +/- 6.0 mm Hg in the nitrendipine group, respectively. Baseline systolic BPs (SBP) were 149.7 +/- 14.4 mm Hg (bunazosin) and 149.2 +/- 14.3 mm Hg (nitrendipine). After 12 weeks of therapy, reduction of DBP (-6.1 +/- 11.7 mm Hg on bunazosin vs -6.9 +/- 9.9 mm Hg on nitrendipine; P = n.s.), and SBP (-4.4 +/- 14.3 mm Hg on bunazosin vs -7.0 +/- 14.4 mm Hg on nitrendipine; P = n.s.) was similar in both groups. During a provocative orthostatic tolerance test after the first dose, the incidence of prae-collapses (ie termination of the test due to orthostatic complaints) was higher on bunazosin (17 vs 2; P < 0.05) but orthostatic dysregulation symptoms (symptom score 1.37 on bunazosin vs 0.95 on nitrendipine; n.s.) and collapses (four on bunazosin vs one on nitrendipine; n.s.) occurred to a similar extent in both treatment groups. Three and 9 weeks after treatment, no increased susceptibility to orthostatic stress compared to baseline could be found in either group. Under daily life conditions, the frequency of orthostatic dysregulation was identical in both groups (0.8%). Bunazosin, however, was far better tolerated with 43.8% of the patients complaining of adverse events as opposed to 63.6% on nitrendipine (P < 0.001). The rate of early discontinuations due to adverse events was only 1.3% on bunazosin compared to 13.6% on nitrendipine (P < 0.001). In conclusion, bunazosin has a similar antihypertensive efficacy as nitrendipine. Despite an initially higher susceptibility to orthostatic stress under a provocative manoeuver, bunazosin evoked the same low incidence of orthostatic dysregulation symptoms as nitrendipine under daily life conditions, but was significantly better tolerated than nitrendipine.

Angiotensin II related to sodium excretion modulates left ventricular structure in human essential hypertension.

BACKGROUND: Urinary sodium excretion and angiotensin II (Ang II), which are linked in a physiological feedback mechanism, have both been described to be blood pressure-independent determinants of left ventricular hypertrophy in essential hypertension. We conducted a study to investigate the interaction of sodium excretion with Ang II and its potential impact on myocardial hypertrophy. METHODS AND RESULTS: Sixty-eight patients (46 men and 22 women; mean age, 52 +/- 10 years) with untreated World Health Organization stage I to II essential hypertension were examined in a cross-sectional study. Left ventricular structure and function (two-dimensionally guided M-mode echocardiography), dietary sodium intake (as estimated by 24-hour urinary sodium excretion), and noninvasive ambulatory blood pressure over 24 hours (Spacelab 90207) were determined in parallel with plasma renin activity and plasma Ang II and serum aldosterone concentrations (radioimmunoassay). Twenty-four-hour urinary sodium excretion emerged as a strong correlate of relative wall thickness independent of 24-hour ambulatory blood pressure (partial r = .49, P < .001). Ang II concentrations were weakly correlated with septal wall thickness (r = .27, P < .05) and left ventricular mass (r = .25, P < .05). Patients with high Ang II concentrations in relation to sodium excretion had a greater left ventricular mass (318 +/- 77 versus 257 +/- 54 g, P < .02), posterior wall thickness (11.8 +/- 1.9 versus 10.5 +/- 0.8 mm, P < .02), and septal wall thickness (13.6 +/- 1.8 versus 11.9 +/- 1.3 mm, P < .01) than those with "relatively low" Ang II levels in relation to sodium excretion. CONCLUSIONS: Impaired suppression of the renin-Ang II system appeared to act as a stimulus for myocardial hypertrophy in hypertensive patients.

Salt and left ventricular hypertrophy: what are the links?

Left ventricular hypertrophy is a frequent and prognostically unfavourable finding in patients with essential hypertension and has been found to be a predictor for the development of essential hypertension in normotensive subjects. Among various genetic, haemodynamic and humoral determinants, dietary salt intake has been demonstrated to influence left ventricular mass in hypertensive disease. Several cross-sectional studies have shown a close relation between dietary salt intake and parameters of left ventricular hypertrophy. Moreover, reduction of dietary sodium intake was associated with a decrease of left ventricular mass in a prospective study. The underlying mechanism of how salt intake modulates myocardial structure has not been explained yet. Three possible explanations are discussed: (1) sodium influences left ventricular mass via raised preload, (2) the sympathetic nervous system acts as a mediator, and (3) the renin-angiotensin-aldosterone system is the responsible link. Recent animal experiments and clinical studies suggest that the renin-angiotensin-aldosterone system may mediate both the cardiotrophic and the blood pressure raising effects of salt. However, not all individuals have a similar high susceptibility to blood pressure elevation develop left ventricular hypertrophy when exposed to high salt intake. We suggest that the underlying mechanism is a dysregulation of the renin-angiotensin-aldosterone system. Some individuals may have an impaired downregulation of angiotensin II synthesis when challenged with high salt intake. Accordingly, we found that relatively too high levels of angiotensin II in relation to urinary sodium excretion were associated with left ventricular hypertrophy in these individuals on high salt intake.