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We aimed to evaluate markers of vascular dysfunction in patients with resistant hypertension (RH). A group of 144 patients (61 years, 42% women) with essential RH were divided in two groups based on ambulatory blood pressure monitoring (ABPM). True RH (72%) was considered when 24-h blood pressure (BP) was ≥ 130 and/or 80 mmHg. Otherwise, patients were classified as white coat RH (28%). Hyperemia-induced forearm vasodilation (HIFV), serum inflammatory biomarkers (hs-CRP, s-ICAM-1, s-VCAM-1, e-selectin, p-selectin and MCP-1) and large (C1) and small arterial (C2) compliance (HDI/Pulse Wave CR 2000) were determined in all individuals. In comparison with patients with white coat RH, and after adjustment for age, office systolic BP and diabetes status, those with true RH had a more impaired HIFV (201 ± 159 vs 436 ± 157%; p < 0.001), increased e-selectin (53.1 ± 29.8 vs 40.7 ± 23.5 ng/ml; p = 0.035), and MCP-1 (445 ± 120 vs 386 ± 126 ng/ml; p = 0.027). No significant differences were observed in arterial compliance. Maximal HIFV inversely correlated with urinary albumin excretion (Rho: - 0.278; p = 0.004) and with some inflammatory biomarkers (MCP-1: - 0.441; p < 0.001, e-selectin: - 0.468; p < 0.001 and p-selectin: - 0.329; p = 0.001). We conclude that true RH, diagnosed by ABPM, is associated with a more severe degree of vascular dysfunction, as measured by HIFV and serum biomarkers, whereas other types of vascular alterations, such as compliance, are not directly linked with the level of BP.

Background and Objective: Most hypertensive patients do not reach target blood pressure (BP), especially if they are diabetic. The objective of the study is to assess the percentage of tight BP control, defined as BP<130/80mm Hg and identify factors associated with it in diabetic type 2 (DM2) patients treated in nephrology units., Patients and Methods: Observational and cross-sectional study; we included 526 patients with DM2 and arterial hypertension (AHT). We collected data on: demographics, anthropometrics, harmful habits, history of cardiovascular disease (CVD), blood pressure, kidney function, glycaemic control, lipid profile, and drug treatment, among others., Results: The mean age (SD) was 66 (10.6) years, 61% were male, 12.8% were smokers, 39.4% had a history of CVD, 72% had hypercholesterolemia, and 44% were obese. Seventeen point five percent of patients had tight BP control (<130/80mm Hg) (95% confidence interval [CI]:14.3-21.0), while 36.9% had BP below 140/85mm Hg. Seventy-one percent of patients were prescribed two or more anti-hypertensive treatments. Several factors are associated with tight BP control not being achieved, and the logistic regression analysis revealed that LDL cholesterol levels were significantly associated (odds ratio [OR] 0.55; 95% CI:0.41-0.75 for one standard deviation increase)., Conclusions: Of the DM2 patients that attended the nephrology units, less than 20% achieved a tight BP control. Cholesterol levels seem to be the main factor associated with unsatisfactory BP control within our study population.

Resistant (or refractory) hypertension (RH) is a clinical diagnosis based on blood pressure (BP) office measurements. About one third of subjects with suspected RH have indeed pseudo-resistant hypertension and 24-h ambulatory-blood pressure-monitoring aids to precisely identify them. Our aim was to determine those clinical, laboratory or echocardiographic variables that may be associated with subjects with sustained hypertension (namely true RH). We carried out a cross-sectional analysis of 143 patients consecutively enrolled with the clinical diagnosis of RH. All patients underwent clinical-demographic, laboratory evaluation, 2D-echocardiography and 24-h ambulatory-blood pressure-monitoring. Pseudo-resistant hypertension or white-coat RH was defined if office BP was > or =140 and/or 90 mm Hg and 24-h BP <130/80 mm Hg. One-hundred and three (72%) patients had true RH and 40 (28%) patients had white-coat RH. True RH patients had significantly higher diabetes prevalence and higher office-systolic blood pressure (SBP) levels. Regarding target organ damage, left ventricular mass index (LVMI) and 24-h urinary albumin excretion (UAE) were also higher in true RH after adjustment for possible confounders (P=0.031 and P=0.012, respectively). In a logistic regression analysis, only office-SBP (multivariate OR (95%CI): 1.030 (1.003-1.057), P=0.030) and UAE (multivariate OR (95% CI): 2.376 (1.225-4.608), P=0.010) were independently associated with true RH. We conclude that true resistant hypertension is associated with silent target organ damage, especially UAE. In patients with suspected RH, assessment of 24 h ambulatory BP is the most accurate way to detect a population with high risk for target-organ damage.

Objectives: To asses the prevalence of target organ damage (TOD) and factors associated with cardiovascular events in subjects with refractory hypertension., Patients and Methods: Cross-sectional study of 146 patients with clinical diagnosis of refractory hypertension. TOD was defined as the presence of microalbuminuria (MA), renal failure (RF), left ventricular hypertrophy (LVH) or left atrial enlargement (LAE). Cardiovascular events were defined as the antecedent of stroke, coronary heart disease, heart failure or peripheral arterial disease. 24-h ambulatory blood pressure monitoring was (ABPM) performed with a validated Spacelabs 90207., Results: The prevalence of LVH was 62.3%, and LAE was observed in 27.7% of the subjects. The prevalence of RF was 28.1% and MA was found in 41,4%. An association between MA and LVH was observed. After adjusting by age, the urinary albumin excretion (UAE) correlated with clinical blood pressure (BP) and BP during 24-h ABPM, whereas LVMI correlated with ambulatory BP but not with clinical BP. The prevalence of previous cardiovascular events was 22% and in the multivariate regression analysis, UAE was the only independent factor associated with the antecedent of cardiovascular events., Conclusion: In subjects with refractory hypertension, the prevalence of TOD was high, and an association between heart and renal organ damage was observed. UAE was independently associated with the antecedent of cardiovascular disease.

This study aims to test the implication of regions on chromosomes 9, 17, and 18 in essential hypertension (EH) by combining sibling-pair linkage analysis and case-control association studies. The selection of these chromosomal regions is based on previous evidence of their implication in EH or in related phenotypes by comparative genomics in several rat models and from genome-wide linkage studies in humans. For the affected sibling-pair linkage analysis, 27 microsatellite markers were genotyped in 56 pedigrees from Spain with hypertensive sibling pairs. Linkage analysis showed significant excess allele sharing at the D18S474 marker on 18q21.1, as shown by maximum likelihood of allele sharing methods (logarithm of odds=3.24; P=0.00011) and nonparametric linkage calculations (nonparametric linkage=3.32; P=0.00044). On the contrary, no significant results with any of the markers analyzed on chromosomes 9 and 17 were obtained. We further focused on the Ring finger and KH domain containing 2 (RKHD2) gene located 6 Kb distal from D18S474 and performed a case-control association study based on linkage disequilibrium in 112 hypertensive patients and 156 control subjects. We selected 2 RKHD2-tagged single nucleotide polymorphisms, rs1941958 and rs1893379, covering, in terms of linkage disequilibrium, the entire gene, and observed a significant overrepresentation of the rs1941958G-rs1893379T RKHD2 haplotype in the group of hypertensive patients in comparison with controls (2P=0.0004; odds ratio: 2.32). We also detected epistatic effects between the 2 RKHD2 single nucleotide polymorphisms (2P=0.002; odds ratio: 2.48). Our data confirm the implication of chromosome 18 in EH and support a contribution of RKHD2 to the genetic susceptibility of this complex phenotype.

The arachidonic acid-derived metabolite 12-(S)hydroxyeicosatetraenoic acid (12(S)-HETE), catalyzed by 12-lipoxygenase (12-LOX, ALOX12), exhibits a variety of biological activities with implications in cardiovascular disease. Previous studies have shown higher urinary excretion of this metabolite in essential hypertension. The aim of this study was to analyze the association of polymorphisms in ALOX12 with hypertension and urinary levels of 12(S)-HETE. We studied 200 patients with essential hypertension (aged 56+/-1 years, mean+/-s.e.m., 97 males) and 166 matched controls (aged 54+/-1 years, 91 males). Out of six polymorphisms in the coding region of ALOX12, only R261Q determined a nonconservative amino-acid change and was evaluated by polymerase chain reaction and restriction digestion. Urinary 12(S)-HETE was measured in Sep-Pack-extracted samples using specific enzyme-linked immunosorbent assay. The distribution of genotypes of the R261Q polymorphism was significantly different between patients and controls: patients 92 (0.46) GG, 84 (0.42) GA, 24 (0.12) AA vs controls 56 (0.34) GG, 78 (0.47) GA, 32 (0.19) AA (P=0.030). On the contrary, no association was observed for two intronic polymorphisms. The urinary excretion of 12(S)-HETE (ng/mg creatinine) was significantly higher in GG homozygous patients (13.0+/-1.5) than in GA (8.2+/-1.8) or in AA (8+/-1.5) patients (P=0.018). These results indicate that a nonsynonymous polymorphism in ALOX12 is associated to essential hypertension and to urinary levels of 12(S)-HETE, thus suggesting a role for this gene in this disease.

Objective: To evaluate the prevalence of hypertension (HT) in prevalent hemodialysis (HD) patients in our region, and to analyze the associated clinical and biochemical variables., Methods: Observational, cross-sectional and multicentric study including a representative sample of prevalent and stable (> 6 months) HD patients from all the HD centers (in and out of Hospitals) in Catalonia, Spain. Clinical and biochemical variables were recorded and predialysis blood pressure (BP) was determined (x3) in each dialysis session during 1 month, as well as the pre/post weight weekly. HT was defined as having at least one of these criteria: a mean (12 determinations) systolic BP > or = 140 mmHg or diastolic BP > or = 90 mmHg or antihypertensive treatment for at least 3 months., Results: The sample comprised 387 patients from 32 of the 40 centers included, 231 of whom where men, with mean age of 63 +/- 14 years. The prevalence of HT in this sample was 67.4%, varying according to the etiology of End-Stage Renal Disease: diabetic 81%, vascular 81%, glomerulonephritis 61%, PKD 52%, unknown and others 64%. The prevalence of additional CV risk factors was 83%. One of each hypertensive 4 patients were treated, of whom 58% had systolic BP > or = 140 or dyastolic > or = 90, in contrast to 28% of untreated patients. The proportion of individuals according to the number of antihypertensive agents was 21% (no agents), 48% (1 agent), 20% (2 agents), 11% (3 agents). Blood pressure was higher among patients receiving higher number of antihypertensive agents. No differences according HT were found in age (64 +/- 13 in hypertensive patients versus 60 +/- 15 in normotensives), time on dialysis (4 +/- 4 vs 4 +/- 4 years), interdialysis weight gain (2.1 +/- 0.8 vs 2.1 +/- 0.8 kg), proportion of weight gain (3.3 +/- 1.4 vs 3.1 +/- 1.4%) or proportion of patients with > 5% weight gain with respect to dry weight (32.5 vs 27.3%). While 84% of hypertensive patients had an additional CV risk factor, this value was 67% in the patients without HT (p < 0.001)., Conclusion: In HD patients HT has a high prevalence in our region and is poorly controlled. The causes of this poor control may be multiple, and weight gain parameters seem not to be a main factor in these stable patients. Due to the aggregation of risk factors in these patients, strategies in order to improve BP control in HD are mandatory.

A polymorphism (C825T) in the gene encoding the G protein beta3 subunit (GNB3) has recently been associated with hypertension and obesity in several populations. The aim of the study was to analyse the relationship between this polymorphism and insulin sensitivity, an hypothesised unifying factor for hypertension and obesity. One hundred thirty unrelated patients with essential hypertension, 70 female and 60 male, aged 58 +/- 1 years with systolic blood pressure of 173 +/- 2 mm Hg and diastolic blood pressure of 105 +/- 1 mm Hg, were genotyped for the GNB3 polymorphism by PCR and restriction digestion with BseDI, and classified in two groups according to the genotypes CC and CT + TT. Body mass index (BMI) was significantly higher in patients with the T allele as compared with patients without the T allele (29.3 +/- 0.4 vs. 26.7 +/- 0.6 kg/m2, p<0.001). On the contrary, there were no differences in the level of systolic or diastolic blood pressure among the genotypes. Insulin sensitivity was measured in a subgroup of 35 patients by means of an euglycemic hyperinsulinemic clamp test. In this subgroup, patients with the T allele displayed lower insulin sensitivity index (1.6 +/- 0.3 vs. 2.7 +/- 0.3 mg/kg/min, p = 0.022), higher fasting serum insulin (121 +/- 16 vs. 77 +/- 11 pmol/L, p = 0.032), higher serum glucose 120 min after 75 g load (9.8 +/- 1.2 vs. 7.0 +/- 0.5 mmol/L, p = 0.038), and higher glycosilated haemoglobin (5.7 +/- 0.4 vs. 4.7 +/- 0.2%; p = 0.042) as compared with patients without the T allele. A regression analysis showed that the association between the T allele and insulin sensitivity was independent of BMI (beta coefficient -0.386, p = 0.022). These results suggest a relationship between the 825T allele of GNB3 and insulin resistance in the essential hypertensive patients studied, which seems to be independent of BMI.

Background: The renin-angiotensin system (RAS) is known to regulate the blood pressure (BP). Several RAS polymorphisms have been associated with essential hypertension (EH), but there is uncertainty about this association. We examined whether the insertion/deletion (I/D) polymorphism of the angiotensin converting enzyme (ACE) gene, and the M235T polymorphism of the angiotensinogen (AGT) gene were associated with EH in a sample of Spanish hipertensive patients., Patients and Method: We studied 1,204 patients with EH (BP > 140/90 mmHg): 668 males, aged 50.8 (13.6) years with systolic BP 151.7 (19.1) and diastolic BP 94.3 (13) mmHg [mean (SD)] and 536 females, aged 52.4 (13.9) years with systolic BP 155.1 (19.8) and diastolic BP 94.5 (12.3) mmHg. As a control group, 367 men and 280 women with no family history of cardiovascular disease who had a normal blood pressure were included. Polymorphisms were determined by PCR amplification of genomic DNA, followed by enzyme digestion for the AGT gene polymorphism., Results: The genotype distribution and allele frequencies of the two RAS polymorphisms were similar in hypertensive and control subjects. Similarly, there were no differences in BP level with regard to the genotype in male or female patients. In addition, we did not find any compound effect of the I/D ACE gene and M235T AGT gene polymorphisms on BP levels in hypertensive subjects., Conclusions: This study suggests that in the population studied, the contribution of the ACE I/D polymorphism and the AGT M235T polymorphism in the development of EH is less important than previously estimated.

It has been reported that both the DD genotype of the angiotensin converting enzyme (ACE) gene and the presence of cerebral white matter lesions (WML) may represent risk factors for the development of stroke. The present study investigates a possible association between 3 different genetic polymorphisms of the renin-angiotensin system and the presence of WML in 60 never-treated essential hypertensive patients (36 men, 24 women), aged 50 to 60 years, without clinical evidence of target organ damage. All patients underwent brain magnetic resonance imaging to establish the presence or absence of WML. The insertion/deletion (I/D) ACE gene, the M235T angiotensinogen (AGT) gene, and the A1166C angiotensin II type 1 receptor gene polymorphisms were determined by standard polymerase chain reaction. Twenty-five hypertensive patients (41.6%) were found to have WML on brain magnetic resonance imaging. No significant association between the M235T angiotensinogen or A1166C angiotensin II type 1 receptor genotypes and the presence of WML was found. However, the frequency of the DD genotype in patients with WML (64%) was significantly higher than that observed in patients without WML (28.6%; P=0.022). The DD genotype odds ratio for the presence of WML was 4.44 (95% confidence interval: 1.48 to 13.3). Likewise, the proportion of the D allele in patients with WML (74%) was significantly higher (P=0.014) than that observed in patients without WML (51.4%). We conclude that the presence of the DD genotype and/or the D allele of the ACE gene may be a predisposing factor for developing WML in essential hypertensive patients. However, because of the small sample size, these results require confirmation in a larger study.

Recently, a C825T polymorphism in the gene coding for the beta3 subunit of G proteins (GNB3) has been described in cells from patients with essential hypertension and enhanced Na+/H+ exchange activity. This study aims to evaluate the association between the 825T allele and activity of erythrocyte sodium/lithium countertransport (Na+/Li+ CT) and other sodium transport systems in red blood cells from patients with essential hypertension. A group of 77 patients (36 male, 41 female; aged 51.7 +/- 1.1 years) was studied. The maximal rates (Vmax) of Na+/Li+ CT, Na+/K+/Cl- cotransport and Na+K+ ATPase were evaluated in erythrocytes from all the patients. They were genotyped for the C825T polymorphism by a polymerase chain reaction (PCR) method, followed by digestion with BseDI. Body mass index (BMI) was higher in CT+TT patients than in CC patients (28.9 +/- 0.5 vs. 27.0 +/- 0.7 kg/m2; P=0.023). Hypertensives with the T allele (CT+TT genotypes) showed significantly higher systolic blood pressure (BP) values (156.9 +/- 2.1 vs. 148.9 +/- 2.8 mmHg; P=0.024), whereas differences in diastolic BP did not reach statistical significance (96.4 +/- 1.0 vs. 94.0 +/- 1.1 mmHg; P=0.120). No differences in the Vmax of Na+/Li+ CT between the genotypes was seen (CC: 236 +/- 19 and CT+TT 277 +/- 23 mmol/L cells per h; P=0.221). Similarly, no differences were detected in the Vmax of erythrocyte Na+/K+/Cl- cotransport and Na+K+ ATPase among the genotypes. There was no appreciable association between the G-protein beta3-subunit C825T polymorphism and erythrocyte Na+/Li+ CT and other sodium transport systems in the hypertensive patient sample studied; however, those with the T allele were more obese and had more severe systolic hypertension.

We analyzed the association between salt sensitivity in essential hypertension and 8 genetic polymorphisms in 6 genes of the renin-angiotensin aldosterone system. Seventy-one patients with essential hypertension were classified as salt sensitive or salt resistant by means of the 24-hour ambulatory blood pressure (BP) change to high salt intake. The polymorphisms evaluated correspond to the following genes: ACE (I/D), angiotensinogen (M235T), angiotensin II type 1 receptor (A1166C), 11beta-Hydroxysteroid dehydrogenase type 2 (11betaHSD2) (G534A), aldosterone synthase (C-344T and Intron 2 conversion), and the mineralocorticoid receptor (G3514C and A4582C); all were determined using standard polymerase chain reaction methods. Thirty-five patients (49%) were classified as salt sensitive. We analyzed the BP response to high salt intake among genotypes and found a significant association for ACE I/D and 11betaHSD2 G534A polymorphisms. Patients homozygous for the insertion allele of the ACE gene (II) had a significantly higher BP increase with high salt intake than did patients homozygous for the deletion allele (DD). Heterozygous patients (ID) exhibited an intermediate response. The prevalence of salt-sensitive hypertension was also significantly higher (P=0.003) in II (68%) and DI patients (59%) compared with DD hypertensives (19%). With respect to 11betaHSD2 G534A, patients with the GG genotype had a significantly higher systolic BP increase with high salt intake than did GA patients. In addition, plasma renin activity suppression in response to high salt was significantly greater in GA patients than in GG patients. The prevalence of salt-sensitive hypertension was 14.3% in GA patients and 50.8% in GG patients (P=0.067). In conclusion, the I allele of ACE I/D polymorphism is significantly associated to salt-sensitive hypertension. The BP response to high salt intake was different among genotypes of ACE I/D and 11betaHSD G534A, suggesting that these polymorphisms may be potentially useful genetic markers of salt sensitivity.

The genetic functional variant C for T in position 825 of the gene encoding G protein beta 3 subunit, GNB3, has been associated with enhanced G protein activation, cell growth and proliferation. This phenotype is associated with enhanced G protein activation and Na(+)-H+ exchanger activity in cells from hypertensive patients. Salt sensitivity affects approximately 50% of hypertensive patients and constitutes an intermediate phenotype determined in part by genetic factors. An association between enhanced Na(+)-H+ exchanger activity and salt sensitivity has been previously reported. The aim of the present study was to investigate the possible association between the G protein polymorphism and salt sensitivity in patients with essential hypertension. A total of 46 patients were studied and classified according to their blood pressure response to a change in sodium intake from low (20 mmol/day) to high (260 mmol/day) into salt sensitive (SS) (n = 20) and salt resistant (SR) (n = 26). GNB3 polymorphism was determined by PCR of genomic DNA and restriction digestion with BseDI. The genotypes distribution among the SS hypertensives was: 8 CC and 12 CT + TT, whereas in SR was: 10 CC and 16 CT + TT (p = 0,577). 24 h mean blood pressure response to salt in the whole group was not different among the different genotypes: CC 4.1 +/- 5.4 mmHg compared to CT + TT 2.9 +/- 6.3 mmHg (p = 0.51). There were no significant differences in the salt induced changes in plasma renin activity, aldosterone, ANP or noradrenaline among the different genotypes. These results indicate that the GNB3 C825T polymorphism has no major influence on the pressor response to salt in essential hypertension and therefore do not support its usefulness as an early genetic marker of salt sensitivity in this disease.

The platelet-type 12-lipoxygenase (12-LO) catalyzes the transformation of arachidonic acid into 12-hydroperoxyeicosatetraenoic acid [12-(S)HPETE], which is reduced to 12-hydroxyeicosatetraenoic acid [12-(S)HETE]. These metabolites exhibit a variety of biological activities such as mediation of angiotensin II-induced intracellular calcium transients in cultured rat vascular smooth muscle cells. It has recently been reported that platelet 12(S)-HETE production is enhanced in the spontaneously hypertensive rat. The pronounced hypotensive effect of LO inhibition in SHR suggests that LO activity may play a role in this form of hypertension. The aim of this study was to determine the basal and thrombin-induced platelet 12(S)-HETE production and the urinary 12(S)-HETE excretion in essential hypertension. We studied 19 patients with this disease (57+/-2 years of age) and 9 normotensive control subjects (48+/-5 years of age) (P:=0.074). 12(S)-HETE was measured in Sep-Pack-extracted samples with specific ELISA and high-performance liquid chromatography. The platelet basal level of 12(S)-HETE was significantly higher in patients than in control subjects (3.56+/-1.22 versus 0.64+/-0.13 ng/10(6) platelets, P:<0.025). In contrast, there were no differences in thrombin-stimulated (1 U/mL) 12(S)-HETE generation: 7.66+/-2.14 in patients versus 4.87+/-1.46 in control subjects (P:=0.61). Platelet 12-LO protein levels, measured by Western blotting with a polyclonal antibody, were higher in the patients than in the control subjects. The urinary excretion of 12(S)-HETE was higher in patients than in control subjects: 36.8+/-7.24 versus 17.1+/-3.14 ng/mg creatinine (P:<0.01). These results indicate that 12(S)-HETE levels and 12-LO protein are increased in patients with essential hypertension, suggesting a role for this metabolite in human hypertension.

We evaluated the association of a common polymorphism in gammaENaC, consisting in a C to G transversion in codon 649, with essential hypertension and to the pressor response to salt in whites. Two hundred fifteen essential hypertensive patients, and 137 normotensive controls were genotyped for the gamma649 ENaC polymorphism by polymerase chain reaction method and diagnostic restriction enzyme digestion. The genotype distribution of the gamma649 ENaC polymorphism in the hypertensives, 129 CC (60%) and 86 CG/GG (40%) was not significantly different from that of the control group, 84 CC (61%) and 53 CG/GG (39%) (P = .81). Salt sensitivity was assessed in a group of 48 patients by 24-h mean blood pressure response to changes in salt intake. Nineteen patients were diagnosed as salt sensitive, whereas 29 had salt-resistant hypertension. The gamma649 ENaC genotype distribution in salt-sensitive patients was 12 CC (63%) and 7 CG/GG (37%), not significantly different from the distribution in the salt-resistant group, 19 CC (65%) and 10 CG/GG (35%), P = .87. The changes in systolic, diastolic, and mean blood pressure as measured by ambulatory blood pressure monitoring, and in plasma renin activity and plasma aldosterone induced by high salt diet were not different among the gamma649 ENaC genotypes. In the present study we found no association between the gamma649 ENaC polymorphism and essential hypertension or salt sensitivity. Although these data do not support a major causative role for this polymorphism, we cannot exclude that a functional mutation elsewhere in ENaC might be associated with essential hypertension.

A functional genetic variant consisting of a C825T substitution in the GNB3 gene, encoding for the G-protein beta(3) subunit, has been associated with enhanced G-protein activation and cell growth. The aim of the study was to investigate the association of this polymorphism with left ventricular hypertrophy (LVH) in a sample of patients with essential hypertension. Left ventricular mass was assessed by 2-mode echocardiography in 86 patients with essential hypertension, and GNB3 C825T genotype was determined by polymerase chain reaction and restriction digestion. Thirty-seven (0.43) patients were homozygous for the C allele (CC), 40 (0.47) were heterozygous (CT), and 9 (0.10) were homozygous for the T allele (TT). The genotype distribution among the patients was in Hardy-Weinberg equilibrium. Values of left ventricular end-diastolic diameter (52.0+/-0.7 versus 48.9+/-0.9 mm, P=0.007), posterior wall thickness (11.3+/-0.2 versus 10.6+/-0.2 mm, P=0.042), and left ventricular mass index (152.7+/-4.4 versus 135.2+/-6.4 g/m(2), P=0. 023) were significantly higher in patients with CT and TT genotypes considered together (CT+TT) than in CC patients. The distribution of the genotypes was significantly different when comparing patients with LVH: 20 (0.33) CC and 40 (0.67) CT+TT patients had this complication, and 17 (0.65) CC and 9 (0.35) CT+TT patients did not (P<0.01). The frequency of the T allele was significantly different among patients with (0.40) and without (0.20) LVH (P<0.01). A logistic regression analysis showed that the association between the T allele and LVH was independent of age, mean blood pressure, body mass index, and alcohol consumption. The relative risk of LVH in patients bearing the T allele (CT+TT group) compared with CC hypertensive patients was 3.03 (95% CI 1.14 to 8.05). The findings suggest an association between LVH and the 825T allele in hypertensive patients.

The possible association between the insertion/deletion (I/D) polymorphism of the angiotensin I converting enzyme (ACE) gene and left ventricular hypertrophy (LVH) was investigated in a group of essential hypertensive patients. Seventy-one essential hypertensive patients (35 men and 36 women), aged 51 +/- 1 years, were genotyped by PCR for the I/D polymorphism of the ACE gene. Cardiac morphology and function were assessed by means of M-mode echocardiography. The relative frequencies of the three genotypes, DD, DI, and II, were respectively: 24%, 55%, and 21%. Mean values of left ventricular mass index were 145, 144, and 150 g/m2 for DD, DI, and II genotypes, without significant differences among them (P = 0.82). Likewise, the prevalence of LVH (76%, 64%, and 87%) was not significantly different among the three genotypes (P = 0.23). We conclude that the ACE gene I/D polymorphism is not associated with LVH in essential hypertension. Journal of Human Hypertension (2000) 14, 47-49.

We evaluated the association between salt-sensitive hypertension and 3 different genetic polymorphisms of the renin-angiotensin system. Fifty patients with essential hypertension were classified as salt sensitive or salt resistant, depending on the presence or absence of a significant increase (P<0.05) in 24-hour ambulatory mean blood pressure (BP) after high salt intake. The insertion/deletion (I/D) angiotensin-converting enzyme (ACE) gene, the M235T angiotensinogen (AGT) gene, and the A1166C angiotensin II type 1 (AT1) receptor gene polymorphisms were determined with the use of standard polymerase chain reaction methods. Twenty-four (48%) patients with significantly increased (P<0.05) 24-hour mean BP with high salt intake (from 107.3+/-9.4 to 114.8+/-10.6 mm Hg) were classified as salt sensitive. In the remaining 26 patients (52%), high salt intake did not significantly modify 24-hour mean BP (from 107.6+/-10 to 107. 8+/-9 mm Hg), and they were classified as having salt-resistant hypertension. We did not find any significant association between either M235T AGT or A1166C AT1 receptor genotypes and the BP response to high salt intake. However, patients with essential hypertension homozygous for the insertion allele of the ACE gene (II) had a significantly higher BP increase with high salt intake (9. 8+/-8.1 mm Hg for systolic BP and 5.2+/-4.2 mm Hg for diastolic BP) than that observed in patients homozygous for the deletion allele (DD) (1.2+/-5.9 mm Hg for systolic BP; P=0.0118 and -0.2+/-4.2 mm Hg for diastolic BP; P=0.0274). Heterozygous patients (ID) exhibited an intermediate response. The prevalence of salt-sensitive hypertension also was significantly higher (P=0.012) in II (67%) and DI patients (62%) compared with DD hypertensives (19%). We conclude that a significant association exists between the I/D polymorphism of the ACE gene and salt-sensitive hypertension. Patients with II and DI genotypes have significantly higher prevalence of salt sensitivity than DD hypertensives.

Background: The renin-angiotensin system (RAS) plays an important role in blood pressure (BP) regulation. A number of RAS polymorphisms have been linked to essential hypertension (EH), but there is uncertainty about this association in other studies. We examined whether the insertion/deletion (I/D) polymorphism of the angiotensin converting enzyme (ACE) gene, and the M235T and T174M polymorphisms of the angiotensinogen (AGT) gene are associated with EH in a Spanish sample of hypertensive patients., Material and Methods: We studied 75 patients with EH (BP > 160/100 mmHg), aged 55 (8.5) years, 30 males, systolic BP (SBP) 182 +/- (22.1) mmHg, diastolic BP (DBP) 109 +/- (9.9) mmHg (mean [SD]) and a strong family history of the disease. As a control group, 75 healthy subjects with no family history of cardiovascular disease were studied. The polymorphisms were determined by PCR amplification of genomic DNA, followed by enzyme digestion for the AGT gene polymorphisms., Results: The genotype distribution and the frequencies of the alleles of the three RAS polymorphisms were similar in hypertensive and control subjects. In addition, we did not find any compound effect of the I/D ACE gene and M235T AGT gene polymorphisms on BP levels in hypertensive and control subjects., Conclusions: In this sample, the contribution of the ACE I/D polymorphism and the AGT M235T and T174M polymorphisms in the development of EH seems to be less important than previously estimated.

An insertion/deletion (I/D) polymorphism of the angiotensin converting enzyme (ACE) gene significantly influences circulating ACE levels and plays a role in the development of target organ damage, that is, left ventricular hypertrophy in essential hypertension (EH), and microalbuminuria in diabetes mellitus. We have examined the role of the I/D polymorphism in essential hypertensive patients with renal involvement. The study was divided in two independent protocols. In protocol 1, we retrospectively analyzed the ACE genotypes in 37 essential hypertensive patients with a clinical and histopathological diagnosis of nephroangiosclerosis. In protocol 2, ACE genotypes as well as microalbuminuria and renal hemodynamic parameters were investigated in 75 patients with EH with normal renal function and a strong family history of hypertension. As control group, 75 healthy subjects with BP < 130/85 mm Hg and no family history of cardiovascular diseases were studied. The ACE variants were determined by PCR and the genotypes were classified as DD, DI and II. In protocol 1, patients with nephroangiosclerosis displayed a significant difference in the genotype distribution (57% DD, 27% DI, 16% II) when compared to the control population (25% DD, 64% DI, 11% II; P < 0.001). There was no significant difference in genotype distribution between hypertensive patients with normal renal function (protocol 2; 33% DD, 59% DI, 8% II) and the control group. There were no differences in age, blood pressure, microalbuminuria and duration of the disease among the three genotypes in the EH group from protocol 2. Taken together, these findings suggest that the DD genotype of ACE is associated with histopathologic-proven kidney involvement in patients with EH and that this polymorphism could be a potential genetic marker in hypertensives at risk of renal complications.

The molecular variants M235T and T174M of the angiotensinogen gene have been linked to essential hypertension in some populations, but there are discrepancies about this association in other studies. We studied 75 patients with essential hypertension (BP > 160/100 mm Hg) from our outpatient clinic, aged 55+/-1 years, 30 men, systolic BP 182+/-2.5, diastolic BP 109+/-1 mm Hg (mean +/- SEM), and a family history of the disease. Target organ damage was evaluated by measuring urinary albumin excretion rate, left ventricular hypertrophy, and fundoscopy. As a control group, 75 healthy subjects with BP < 130/85 mm Hg and with no family history of cardiovascular disease were selected. M235T and T174M angiotensinogen genotypes were determined by PCR and subsequent digestion of the products with SfaNI and NcoI, respectively. The frequency (q) of genotypes of the variant M235T in the patients with essential hypertension was MM 0.31, MT 0.41, and TT 0.28, not significantly different (P = .93) from that of the controls (MM 0.28, MT 0.44, and TT 0.28). For the variant T174M, the genotype frequencies in hypertensives were TT 0.83, TM 0.15, and MM 0.02, which was not significantly different (P = .89) from that of the controls (TT 0.86, TM 0.12, and MM 0.02). Similarly, there was no evidence for association between angiotensinogen genotypes and hypertension in subjects aged < or = 40 years old (n = 24) or with severe (stage III) hypertension (n = 31). Within the group of patients with essential hypertension, there were no differences in genotype distribution between patients with and without retinopathy (n = 31), left ventricular hypertrophy (n = 37), or microalbuminuria (n = 14). This study shows that M235T and T174M variants are not associated either with essential hypertension or with target organ damage in a Spanish sample.

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

We evaluated changes in erythrocyte sodium transport systems, platelet pH, and calcium concentration induced by low and high salt intakes in a group of 50 essential hypertensive patients classified on the basis of their salt sensitivity. Patients received a standard diet with 20 mmol NaCl daily for 2 weeks supplemented in a single-blind fashion by placebo tablets the first 7 days and NaCl tablets the following 7 days. Salt sensitivity, defined as a significant rise (P <.05) in 24-hour mean blood pressure obtained by ambulatory blood pressure monitoring, was diagnosed in 22 (44%) patients. The remaining 28 (56%) were considered to have salt-resistant hypertension. In the entire group of hypertensive patients, high salt intake promoted a significant increase (P <.05) in the maximal rate of erythrocyte NA(+)-Li(+) countertransport (from 271 +/- 19 to 327 +/- 18 microM/(L cells/h) and of the Na(+)-dependent HCO3(-)-CL(-) exchanger (from 946 +/- 58 to 1237 +/- 92 microM/L cells/h) as well as in platelet pH (from 7.15+/-0 0.01 to 7.19+/-0.02 and calcium concentration (from 49+/-2 to 57 +/-2 nmol/L). Depending on salt sensitivity, high salt intake promoted opposing changes in some of the sodium transport systems studied. Salt-sensitive patients increased the maximal rate of the erythrocyte Na(+)-K(+) pump (fom 7.0 +/- 0.4 to 8.8 +/- 0.4 mmol/(L cells/h), Na(+)-K(+)-Cl(-) cotransport (from 416 +/- 37 to 612 +/- 41 micromol/(L cells/h), Na(+)-Li(+) countertransport (from 248 +/- 20 to 389 +/- 17 micromol/(L cells/h) at the end of the high salt period. Conversely, salt-resistant patients decreased the Na(+)-K(+) pump (from 8.0 +/- 0.4 to 6.9 +/- 0.3 mmol/(L cells/h) and Na(+)-K(+)-Cl(-) cotransport (from 578 +/- 53 to 481 +/- 43 micromol/(L cells/h). We conclude that modulation of erythrocyte sodium transport systems by high salt intake depends on salt sensitivity. The Na(+)-K(+) pump, Na(+)-K(+)-Cl(-) cotransport, and Na(+)-Li(+) countertransport increase in salt-sensitive patients, whereas the activity of these sodium transport systems tends to decrease in salt-resistant patients. Independent of salt sensitivity, high salt intake promotes a significant increase in the erythrocyte Na(+)-dependent HCO3(-)-Cl(-) exchanger, platelet pH, and calcium concentration in essential hypertensive patients.

The aim was to investigate circulating levels of immunoreactive endothelin (ir-ET) in atherosclerotic renovascular hypertension (RVH), and to assess the role of the kidneys in its overall plasma concentration. We studied 16 hypertensive patients with renal artery stenosis evidenced by angiography and admitted to hospital for the diagnostic evaluation of RVH by renal vein plasma renin activity (PRA) determinations. The right femoral vein was catheterized to simultaneously measure PRA and ir-ET in both renal veins and inferior vena cava below the origin of the renal veins. RVH was present in 9 patients as indicated by diagnostic PRA renal vein ratios and the remaining 7 patients were considered to have essential hypertension (EH). Patients with RVH showed a marked increase in systemic plasma ir-ET concentration (10.3 +/- 0.9 pg/ml). Despite a significant increase of PRA in the vein of the ischemic (IK) versus the contralateral (CK) kidney in patients with RVH, no significant differences in ir-ET concentration were observed between both kidneys. These results indicate that patients with RVH have increased circulating levels of ir-ET. However, the higher systemic plasma ir-ET do not arise from the renal circulation, since plasma ir-ET is significantly higher in systemic circulation than in renal veins.

To investigate the possible relationships between blood pressure, parathyroid hormone (PTH) and platelet cytosolic Ca2+ concentration ([Ca2+]i) in patients with essential hypertension, we studied 17 patients with this disease aged 48 +/- 2 years and 17 normotensive controls aged 44 +/- 3 years. Platelet [Ca2+]i was measured by spectrofluorimetry using the dye Fura-2 acetoxymethylester. Patients with essential hypertension displayed lower levels of serum ionized Ca2+ (0.99 +/- 0.03 versus 1.1 +/- 0.01 mmol/l, P < 0.05) and higher serum intact PTH levels (37 +/- 3 versus 26 +/- pg/ml, (P < 0.01) than the normotensive controls. Although serum levels of intact PTH were significantly correlated with mean arterial pressure (MAP) in the combined group of subjects (r = 0.42, P < 0.05), there was no correlation when each group was considered separately. Resting platelet [Ca2+]i was also higher in patients than in controls (57 +/- 3 versus 48 +/- 2 nmol/l, P < 0.005). When platelets were stimulated in vitro with thrombin, the increment in [Ca2+]i was also greater in patients than in controls in the presence of extracellular Ca2+ (264 +/- 24 versus 194 +/- 19 nmol/l, P < 0.05) but not in its absence (123 +/- 12 versus 112 +/- 10 nmol/l). The thrombin-induced increment in [Ca2+]i was correlated with MAP in the hypertensive patients (r = 0.64, P < 0.01) and in the combined group of subjects (r = 0.42, P < 0.05). There was no relationship between resting or thrombin-induced [Ca2+]i and serum PTH in either group of patients or in the combined group of subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

The platelet intracellular calcium concentration ([Ca2+]i) and intracellular pH (pHi) were measured by spectrofluorimetry with the dyes Fura-2 and BCECF, respectively, in 19 patients with essential hypertension (10 males), aged 48 +/- 2 years, before and after 12 weeks of antihypertensive treatment and in 19 normotensive controls (11 males), aged 46 +/- 3 years. [Ca2+]i and pHi were measured in the resting state and after stimulation in vitro with 0.1 U/ml human thrombin. In patients with essential hypertension, both resting [Ca2+]i (61 +/- 4 nmol/l) and thrombin-induced maximal increase in [Ca2]i (291 +/- 26 nmol/l) were significantly (P < 0.01) greater than in the normotensive controls (resting 49 +/- 2 nmol/l and thrombin-induced 199 +/- 21 nmol/l). With respect to pHi, no difference in resting pHi between both groups was found (7.16 +/- 0.01 vs. 7.16 +/- 0.01). However, pHi increment at 300 seconds in response to thrombin was higher in the patients with essential hypertension than in the controls (0.131 +/- 0.02 vs. 0.083 +/- 0.01 pH units, P < 0.05). The increment in pHi was blunted by the amiloride derivative EIPA, indicating that it was mediated by the Na+/H+ exchanger. After antihypertensive therapy in the essential hypertensive patients, basal [Ca2+]i was significantly reduced (52 +/- 2 nmol/l, P < 0.01) and was not statistically different to the value found in the normotensive controls. Resting pHi suffered no significant modification after treatment (7.17 +/- 0.01, P = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

To investigate the relationship between changes in intracellular calcium concentration ([Ca2+]i) and agonist-induced activation of the Na+/H+ exchanger in essential hypertension (EH), platelet [Ca2+]i and pHi were measured in 24 patients with EH (14 males) aged 48 +/- 2 years and 23 matched normotensive controls (NT) (12 males) aged 45 +/- 3 years. Measurements were done with spectrofluorimetry using the dyes Fura-2 for [Ca2+]i and BCECF for pHi. [Ca2+]i and pHi were measured in the resting condition and after stimulation in vitro with 0.1 U/ml human thrombin. The thrombin-induced rise in pHi was Na+ dependent and amiloride sensitive, indicating that it was mediated by the Na+/H+ exchanger. Unstimulated [Ca2+]i was higher in patients with EH than in NT (60 +/- 3 vs. 48 +/- 1 nmol/liter, P < 0.005), but there were no differences in resting pHi between both groups (7.16 +/- 0.01 vs. 7.16 +/- 0.008). In the presence of 1 mmol/liter external calcium (Ca2+o), thrombin-induced increment in [Ca2+]i was significantly greater in patients with EH than in NT (281 +/- 21 vs. 206 +/- 19; P < 0.05) as was the pHi increment (EH: 0.137 +/- 0.01; NT: 0.095 +/- 0.01; P < 0.05). Both agonist-induced increments in [Ca2+]i and in pHi were correlated with mean arterial pressure (MAP) only in the EH group (r = 0.58, P < 0.005 and r = 0.59, P < 0.005, respectively). The agonist-induced rise in pHi was positively correlated with the rise in [Ca2+]i both in the EH group (r = 0.65, P < 0.001) and in the NT (r = 0.55, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)