Chronotherapy in hypertension: a pill at night makes things right?

Greater natriuretic response to ENaC inhibition in male versus female Sprague-Dawley rats

Genes for the epithelial sodium channel (ENaC) subunits are expressed in a circadian manner, but whether this results in time-of-day differences in activity is not known. Recent data show that protein expression of ENaC subunits is higher in kidneys from female rats, yet females are more efficient in excreting an acute salt load. Thus, our in vivo study determined whether there is a time-of-day difference as well as a sex difference in the response to ENaC inhibition by benzamil. Our results showed that the natriuretic and diuretic responses to a single dose of benzamil were significantly greater in male compared with female rats whether given at the beginning of the inactive period [Zeitgeber time 0 (ZT0), 7 AM] or active period (ZT12, 7 PM). However, the response to benzamil was not significantly different between ZT0 and ZT12 dosing in either male or female rats. There was no difference in renal cortical α-ENaC protein abundance between ZT0 and ZT12 or males and females. Given previous reports of flow-induced stimulation of endothelin-1 (ET-1) production and sex differences in the renal endothelin system, we measured urinary ET-1 excretion to assess the effects of increased urine flow on intrarenal ET-1. ET-1 excretion was significantly increased following benzamil administration in both sexes, but this increase was significantly greater in females. These results support the hypothesis that ENaC activity is less prominent in maintaining Na⁺ balance in females independent of renal ET-1. Because ENaC subunit genes and protein expression vary by time of day and are greater in female rat kidneys, this suggests a clear disconnect between ENaC expression and channel activity.

Effects of Chronic Intractable Insomnia on Inflammatory Cytokines, Blood Pressure Characteristics, and Antihypertensive Efficacy in Hypertensive Patients

BACKGROUND This study investigated the changes in blood pressure and inflammatory cytokines in patients with chronic intractable insomnia, and explored the effects of chronic intractable insomnia on antihypertensive efficacy. MATERIAL AND METHODS A total of 248 patients with hypertension admitted to our hospital from 2008 to 2017 were enrolled. We enrolled 124 patients without chronic insomnia in the control group, while 124 patients with chronic insomnia were included in the treatment group. The treatment group received estazolam and was further subdivided into the effective group (n=96) and the ineffective group (n=28) according to Sleep Dysfunction Rating Scale (SDRS) scores. Sleep quality before and after treatment was determined. RESULTS Antihypertensive treatment with eplerenone (50 mg) significantly reduced SDRS scores, C-reactive protein (CRP), tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), matrix metalloproteinase-9 (MMP-9), serum intercellular adhesion molecules (sICAM), and IL-1β levels, as well as systolic blood pressures (SBP) and diastolic blood pressures (DBP), with elevation of non-dipper blood pressure rhythm (P<0.05). The inhibition of intractable insomnia significantly downregulated SBP and DBP, as well as serum inflammatory cytokines such as CRP and TNF-α, showing a favorable effect on antihypertensive function. CONCLUSIONS Alleviation of chronic intractable insomnia facilitates hypertension therapy through decreasing levels of inflammatory cytokines and the proportion of non-dipper blood pressure rhythm, which offers insights for the treatment of hypertension.

Ethical complexities in standard of care randomized trials: A case study of morning versus nighttime dosing of blood pressure drugs

BACKGROUND

Pragmatic trials comparing "standard of care" treatments provide comparative effectiveness data to make practice of medicine more evidence-based. With electronic health records, recruiting and conducting such trials can be relatively inexpensive. But some worry that the traditional research ethics framework poses unnecessary obstacles and is not appropriate for evaluating such clinical trials. This concern is based on the view (which we call the "Standard of Care Principle") that such research is similar to usual clinical practice and therefore does not raise significant ethical issues since everyone in the research study will receive an accepted standard of care treatment.

METHODS

A case study of a pragmatic randomized clinical trial (Blood Pressure Medication Timing study) comparing morning versus nighttime dosing of antihypertensive medications. The Blood Pressure Medication Timing study has been proposed as a paradigm example of why the Standard of Care Principle obviates the need for traditional levels of ethical scrutiny and how the current regulatory framework poses unnecessary obstacles to research. We provide an ethical analysis of the Blood Pressure Medication Timing study, drawing on the empirical literature as well as on normative analysis.

RESULTS

The Standard of Care Principle is the main ethical rationale given by commentators for asserting that the Blood Pressure Medication Timing study does not require "significant ethical debate" and by investigators for the assertion that the Blood Pressure Medication Timing study is minimal risk and thus eligible for lessened regulatory requirements. However, the Blood Pressure Medication Timing study raises important ethical issues, including whether it is even necessary, given the considerable randomized clinical trial evidence in support of nighttime dosing, a much larger (N≈17,000) confirmatory randomized clinical trial already in progress, evidence for safety of nighttime dosing, and the cost-free availability of the intervention. Furthermore, the Standard of Care Principle provides a misleading basis for analyzing the informed consent requirements, especially regarding the requirement to disclose alternative courses of treatment that "might be advantageous to the subject."

CONCLUSION

The Standard of Care Principle is ethically inadequate and misleading even when it is applied to the pragmatic randomized clinical trial proposed as a paradigm case for its application.

Effects of chronotherapy of benazepril on the diurnal profile of RAAS and clock genes in the kidney of 5/6 nephrectomy rats

This study investigated the effects of benazepril administered in the morning or evening on the diurnal variation of renin-angiotensin-aldosterone system (RAAS) and clock genes in the kidney. The male Wistar rat models of 5/6 subtotal nephrectomy (STNx) were established. Animals were randomly divided into 4 groups: sham STNx group (control), STNx group, morning benazepril group (MB) and evening benazepril group (EB). Benazepril was intragastrically administered at a dose of 10 mg/kg/day at 07:00 and 19:00 in the MB group and EB group respectively for 12 weeks. All the animals were synchronized to the light:dark cycle of 12:12 for 12 weeks. Systolic blood pressure (SBP), 24-h urinary protein excretion and renal function were measured at 11 weeks. Blood samples and kidneys were collected every 4 h throughout a day to detect the expression pattern of renin activity (RA), angiotensin II (AngII) and aldosterone (Ald) by radioimmunoassay (RIA) and the mRNA expression profile of clock genes (bmal1, dbp and per2) by real-time PCR at 12 weeks. Our results showed that no significant differences were noted in the SBP, 24-h urine protein excretion and renal function between the MB and EB groups. There were no significant differences in average Ald and RA content of a day between the MB group and EB group. The expression peak of bmal1 mRNA was phase-delayed by 4 to 8 h, and the diurnal variation of per2 and dbp mRNA diminished in the MB and EB groups compared with the control and STNx groups. It was concluded when the similar SBP reduction, RAAS inhibition and clock gene profile were achieved with optimal dose of benazepril, morning versus evening dosing of benazepril has the same renoprotection effects.