Clinical predictors of the response to short-term thiazide treatment in nondiabetic essential hypertensives

Integrated renal and sympathetic mechanisms underlying the development of sex- and age-dependent hypertension and the salt sensitivity of blood pressure

Aging is a non-modifiable understudied risk factor for hypertension. We hypothesized that sympathetically mediated activation of renal sodium reabsorption drives age-dependent hypertension and the salt sensitivity of blood pressure (BP). Using 3-, 8-, and 16-month-old male and female Sprague-Dawley rats as a model of normal aging, we assessed BP, indices of sympathetic tone, and the physiological responses to acute and chronic sodium challenge including sodium chloride cotransporter (NCC) regulation. The effects of renal nerve ablation and NCC antagonism were assessed in hypertensive male rats. We observed sex-dependent impaired renal sodium handling (24 h sodium balance (meq), male 3-month 0.36 ± 0.1 vs. 16-month 0.84 ± 0.2; sodium load excreted during 5% bodyweight isotonic saline volume expansion (%) male 3-month 77 ± 5 vs. 16-month 22 ± 8), hypertension (MAP (mmHg) male 3-month 123 ± 4 vs. 16-month 148 ± 6), and the salt sensitivity of BP in aged male, but not female, rats. Attenuated sympathoinhibitory afferent renal nerve (ARN) responses contributed to increased sympathetic tone and hypertension in male rats. Increased sympathetic tone contributes to renal sodium retention, in part through increased NCC activity via a dysfunctional with-no-lysine kinase-(WNK) STE20/SPS1-related proline/alanine-rich kinase signaling pathway, to drive hypertension and the salt sensitivity of BP in aged male rats. NCC antagonism and renal nerve ablation, which reduced WNK dysfunction and decreased NCC activity, attenuated age-dependent hypertension in male Sprague-Dawley rats. The contribution of an impaired sympathoinhibitory ARN reflex to sex- and age-dependent hypertension in an NCC-dependent manner, via an impaired WNK1/WNK4 dynamic, suggests this pathway as a mechanism-based target for the treatment of age-dependent hypertension.

Pressure-Natriuresis Response Is Diminished in Old Age

BACKGROUND

Age-related alterations in renal sodium handling affect blood pressure (BP). We aimed to clarify whether the pressure-natriuresis response changes with age, leading to BP elevation.

METHODS

A total of 4,859 participants with normal renal function from the Korean Genome and Epidemiology Study (KoGES) and 235 patients with non-diabetic chronic kidney disease (CKD) from the ESPECIAL trial were included and divided into the younger and older groups. In ESPECIAL, participants took olmesartan from weeks 0 to 16 and were educated about a low-salt diet (LSD) from weeks 8 to 16.

RESULTS

In both studies, older participants showed lower estimated glomerular filtration rate (eGFR) and urine concentration index and higher albuminuria. In KoGES, BP was higher and urine sodium was lower in older participants. In ESPECIAL, diastolic BP at 0 week was lower in older participants. Olmesartan reduced BP in both groups, whereas LSD decreased systolic BP only in older participants. Urine sodium increased in younger participants but decreased in older participants after olmesartan use. In KoGES, urine sodium was correlated with BP in both groups after adjusting for age, sex, and eGFR; however, the correlation coefficient was lower in older participants. In ESPECIAL, only younger participants showed a significant positive association between systolic BP and urine sodium in multiple regression analysis.

CONCLUSIONS

The pressure-natriuresis response was diminished in older participants with or without CKD.

Mechanisms of altered renal sodium handling in age-related hypertension

The prevalence of hypertension rises with age to approximately two out of three adults over the age of 60 in the United States. Although the mechanisms underlying age-related hypertension are incompletely understood, sodium homeostasis is critical to the long-term regulation of blood pressure and there is strong evidence that aging is associated with alterations in renal sodium handling. This minireview focuses on recent advancements in our understanding of the vascular, neurohumoral, and renal mechanisms that influence sodium homeostasis and promote age-related hypertension.

Telmisartan and hydrochlorothiazide antihypertensive treatment in high sodium intake population: a randomized double-blind trial

OBJECTIVES

To compare the blood pressure (BP)-lowering effects of telmisartan 40 mg/day and hydrochlorothiazide (HCTZ) 25 mg/day in high sodium intake patients with mild-to-moderate hypertension in China.

METHODS

In this randomized, double-blind trial, eligible patients were randomly divided into telmisartan and HCTZ groups with three follow-ups scheduled on days 15, 30, and 60 after enrollment to compare BP decrease, hypokalemia, and other adverse events after intervention.

RESULTS

A total of 1333 mild-to-moderate hypertensive patients with average sodium intake of 5909 mg/day were enrolled from 14 county hospitals in China. Baseline characteristics were well balanced. At 15, 30, and 60 days of follow-up, average SBP/DBP reduction in telmisartan and HCTZ group was 12.5/8.0, 14.3/9.1, 12.8/7.2, 11.0/5.8, 13.6/7.1, and 11.5/5.3 mmHg, respectively. Telmisartan showed greater BP response than HCTZ at three visits, with statistical significance for DBP (P < 0.001) regardless of the adjustment for baseline BP, sodium excretion, and pulse pressure (PP). SBP reduction was positively related to increasing urinary sodium and PP levels for patients in both groups but increased faster with increasing PP in HCTZ than in telmisartan (P = 0.0238 for group × PP). Compared with telmisartan, HCTZ showed more hypokalemia (0.4 vs. 4.5%, P < 0.001).

CONCLUSION

Both telmisartan and HCTZ were effective for the treatment of hypertensive patients with high sodium intake. Telmisartan showed better DBP-lowering effect and less hypokalemia than HCTZ among high sodium intake patients. Further studies are needed to evaluate the plausible superiority effect of hydrochlorothiazide among patients with large PP.

Hypertension subtypes modify metabolic response to thiazide diuretics

BACKGROUND

Blood pressure (BP) and metabolic response to thiazide diuretics might be varied in patients with different hypertension subtypes and ethnicities. This study aimed to investigate the response of BP and metabolic profiles to short-term thiazide treatment in an Asian cohort with different hypertension subtypes.

DESIGN

Serial ethnic Chinese nondiabetic subjects with hypertension were evaluated. After diet instruction and lifestyle modification for 2 weeks, patients who still had elevated systolic BP (SBP≥140 mmHg) and/or diastolic BP (DBP≥90 mmHg) were given 50 mg of hydrochlorothiazide daily for 2 weeks. The responses of BP and metabolic profiles were evaluated before and after treatment according to the patient's baseline BP subtype - isolated systolic hypertension (ISH), systo-diastolic hypertension (SDH) and isolated diastolic hypertension (IDH).

RESULTS

Hydrochlorothiazide treatment significantly reduced the BP in all 92 patients (62 males, aged 45·7 ± 9·6 years), irrespective of their baseline BP subtypes. In patients with SDH (n = 39) or IDH (n = 40), hydrochlorothiazide treatment significantly increased serum adiponectin (P = 0·001 and 0·007, respectively) and reduced asymmetric dimethylarginine levels (P < 0·001, in both groups). Serum cholesterol (P = 0·027) and fasting blood sugar levels (P = 0·044) were significantly improved only in the IDH patients. Furthermore, IDH was independently associated with changes in fasting blood sugar (β = -11·178, P = 0·022) and cholesterol (β = -22·654, P = 0·027).

CONCLUSIONS

The characteristics of the Asian hypertensive patients with diastolic hypertension can present a favourable metabolic response to the short-term hydrochlorothiazide treatment. The potential positive effect on cardiovascular risk should be validated in long-term studies in this diastolic type of hypertension.

Association of circadian genes with diurnal blood pressure changes and non-dipper essential hypertension: a genetic association with young-onset hypertension

Recent studies have suggested that circadian genes have important roles in maintaining the circadian rhythm of the cardiovascular system. However, the associations between diurnal BP changes and circadian genes remain undetermined. We conducted a genetic association study of young-onset hypertension, in which 24-h ambulatory blood pressure (BP) monitoring was performed. A total of 23 tag single-nucleotide polymorphisms (SNPs) on 11 genes involved in circadian rhythms were genotyped for correlations with diurnal BP variation phenotypes. A permutation test was used to correct for multiple testing. Five tag SNPs within five loci, including rs3888170 in NPAS2, rs6431590 in PER2, rs1410225 in RORββ, rs3816358 in BMAL1 and rs10519096 in RORα, were significantly associated with the non-dipper phenotype in 372 young hypertensive patients. A genetic risk score was generated by counting the risk alleles and effects for each individual. Genotyping was performed in an additional independent set of 619 young-onset hypertensive subjects. Altogether, non-dippers had a higher weighted genetic risk score than dippers (1.67±0.56 vs. 1.54±0.55, P<0.001), and the additive genetic risk score also indicated a graded association with decreased diurnal BP changes (P=0.006), as well as a non-dipper phenotype (P=0.031). After multivariable logistic analysis, only the circadian genetic risk score (odds ratio (OR), 1550; 95% confidence interval (CI), 1.225-1.961, P<0.001) and the use of β-blockers (OR, 1.519; 95% CI, 1.164-1.982, P=0.003) were independently associated with the presence of non-dippers among subjects with young-onset hypertension. Genetic variants in circadian genes were associated with the diurnal phenotype of hypertension, suggesting a genetic association with diurnal BP changes in essential hypertension.

A novel SNP associated with nighttime pulse pressure in young-onset hypertension patients could be a genetic prognostic factor for cardiovascular events in a general cohort in Taiwan

Background

Pulse pressure (PP) is a risk factor for cardiovascular disease. It has been reported that ambulatory blood pressure (BP) and nighttime BP parameters are heritable traits. However, the genetic association of pulse pressure and its clinical impact remain undetermined.

Method and Results

We conducted a genome-wide association study of PP using ambulatory BP monitoring in young-onset hypertensive patients and found a significant association between nighttime PP and SNP rs897876 (p = 0.009) at chromosome 2p14, which contains the predicted gene FLJ16124. Young-onset hypertension patients carrying TT genotypes at rs897876 had higher nighttime PP than those with CT and CC genotypes (TT, 41.6±7.3 mm Hg; CT, 39.1±6.0 mm Hg; CC, 38.9±6.3 mm Hg; p<0.05,). The T risk allele resulted in a cumulative increase in nighttime PP (β = 1.036 mm Hg, se. = 0.298, p<0.001 per T allele). An independent community-based cohort containing 3325 Taiwanese individuals (mean age, 50.2 years) was studied to investigate the genetic impact of rs897876 polymorphisms in determining future cardiovascular events. After an average 7.79±0.28 years of follow-up, the TT genotype of rs897876 was independently associated with an increased risk (in a recessive model) of coronary artery disease (HR, 2.20; 95% CI, 1.20–4.03; p = 0.01) and total cardiovascular events (HR, 1.99; 95% CI, 1.29–3.06; p = 0.002), suggesting that the TT genotype of rs897876C, which is associated with nighttime pulse pressure in young-onset hypertension patients, could be a genetic prognostic factor of cardiovascular events in the general cohort.

Conclusion

The TT genotype of rs897876C at 2p14 identified in young-onset hypertensive had higher nighttime PP and could be a genetic prognostic factor of cardiovascular events in the general cohort in Taiwan.

Genetic variation in renin predicts the effects of thiazide diuretics

BACKGROUND

While genetic variants of renin-angiotensin-aldosterone system (RAAS) may modify the blood pressure (BP) response to thiazide diuretics, there was no evidence of genetic variations in renin (REN) playing a role. This study aimed to address the potential effects of genetic variations of RAAS on the response to initial treatment of hydrochlorothiazide (HCTZ).

MATERIALS AND METHODS

We enrolled nondiabetic hypertensive patients with a systolic blood pressure (SBP) ≥140 or a diastolic blood pressure (DBP) ≥90mmHg, who were either previously untreated or unsatisfactorily treated. After lifestyle modification and diet instruction for 2weeks, 90 patients with persistently elevated BP were given HCTZ 50 mg every morning for 2 weeks. Single nucleotide polymorphism markers were selected from genes involving in RAAS, including rs7079 and rs699 of angiotensinogen, rs4293 and rs4353 of angiotensin-converting enzyme and rs1464816 and rs11240688 of REN.

RESULTS

The patients were divided into three groups according to the SBP response after HCTZ. The upper 1/3 responders had older age (P=0·035), higher SBP (P=0·039), higher pulse pressure (P=0·006) and lower plasma REN activity (PRA) (P=0·020) when compared with the lower 1/3 responders. Renin rs11240688 CC polymorphism (β=9·931, corrected P=0·012), Log PRA (β=7·451, P=0·004) and baseline SBP (β=0·299, P=0·006) were the independent predictors for the BP lowering response.

CONCLUSIONS

In addition to PRA, renin rs11240688 CC polymorphism may also independently predict the effect of HCTZ.