Blood pressure variability provokes vascular β-adrenoceptor desensitization in rats

Synergetic Action of Forskolin and Mevastatin Induce Normalization of Lipids Profile in Dyslipidemic Rats through Adenosine Monophosphate Kinase Upregulation

In the present study, we examined the synergetic effect of forskolin and mevastatin administration on lipid profile and lipid metabolism in omental adipose tissue in dyslipidemic rats. The study was conducted on forty male albino rats. The rats were randomly classified into four main groups of ten animals in each group as follows: group A, served as control nontreated; group B, rats that received Triton WR 1339 (500 mg/kg); group C, rats that received Triton WR 1339 with forskolin (100% FSK extract 0.5 mg/kg/day) for four weeks; and group D, dyslipidemic rats received both mevastatin and forskolin. At the end of the experimental period, blood and omental adipose tissue samples were collected, preserved, and used for biochemical determination of lipid profile and mRNA expression profile of adenylate cyclase (AC), hormone-sensitive lipase, respectively (HSL), and adenosine monophosphate-activated protein kinase (AMPK). The results showed a significant decline in the serum concentration of total cholesterol, LDL-cholesterol, and triglycerides, although there was a significant increase in serum levels of HDL-cholesterol and glycerol in rats received forskolin alone or with mevastatin when compared with control and dyslipidemic groups. The mRNA expression levels of AC, HSL, and AMPK were significantly increased in omental adipose tissue of rats received forskolin when compared with other groups. In conclusion, forskolin acts synergistically with mevastatin to lower lipid profile and improve lipid metabolism in dyslipidemic rats through upregulation of AMPK expression.

Association of 1-Year Blood Pressure Variability With Long-term Mortality Among Adults With Coronary Artery Disease: A Post Hoc Analysis of a Randomized Clinical Trial

Importance

Accumulating evidence indicates that higher blood pressure (BP) variability from one physician office visit to the next (hereafter referred to as visit-to-visit BP variability) is associated with poor outcomes. Short-term measurement (throughout 1 year) of visit-to-visit BP variability in high-risk older patients may help identify patients at increased risk of death.

Objective

To evaluate whether short-term visit-to-visit BP variability is associated with increased long-term mortality risk.

Design, Setting, and Participants

The US cohort of the International Verapamil SR-Trandolapril Study (INVEST), a randomized clinical trial of 16 688 patients aged 50 years or older with hypertension and coronary artery disease, was conducted between September 2, 1997, and December 15, 2000, with in-trial follow-up through February 14, 2003. The study evaluated a calcium antagonist (sustained-release verapamil plus trandolapril) vs β-blocker (atenolol plus hydrochlorothiazide) treatment strategy. Blood pressure measurement visits were scheduled every 6 weeks for the first 6 months and biannually thereafter. Statistical analysis was performed from September 2, 1997, to May 1, 2014.

Exposures

Visit-to-visit systolic BP (SBP) and diastolic BP variability during the first year of enrollment using 4 different BP variability measures: standard deviation, coefficient of variation, average real variability, and variability independent of the mean.

Main Outcomes and Measures

All-cause death, assessed via the US National Death Index, beginning after the exposure assessment period through May 1, 2014.

Results

For the present post hoc analysis, long-term mortality data were available on 16 688 patients (9001 women [54%]; mean [SD] age, 66.5 [9.9] years; 45% White patients, 16% Black patients, and 37% Hispanic patients). During a mean (SD) follow-up of 10.9 (4.2) years, 5058 patients (30%) died. All 4 variability measures for SBP were significantly associated with long-term mortality after adjustment for baseline demographic characteristics and comorbidities. After comparison of lowest vs highest variability measure quintiles, the magnitude of the association with death remained statistically significant even after adjustment for baseline demographic characteristics and comorbidities (average real variability: adjusted hazard ratio [aHR], 1.18; 95% CI, 1.08-1.30; standard deviation: aHR, 1.14; 95% CI, 1.04-1.24; coefficient of variation: aHR, 1.15; 95% CI, 1.06-1.26; variability independent of the mean: aHR, 1.15; 95% CI, 1.05-1.25). The signal was stronger in women compared with men. Associations of diastolic BP variability measures with death were weaker than for SBP and were not significant after adjustment.

Conclusions and Relevance

This study suggests that, in a large population of older patients with hypertension and coronary artery disease, short-term visit-to-visit SBP variability was associated with excess long-term mortality, especially for women. Efforts to identify and minimize visit-to-visit SBP variability may be important in reducing excess mortality later in life.

Trial Registration

ClinicalTrials.gov Identifier: NCT00133692.

Association Between Visit-to-Visit Blood Pressure Variability in Early Adulthood and Myocardial Structure and Function in Later Life

Importance

Long-term blood pressure (BP) variability has emerged as a reproducible measure that is associated with heart failure independent of systemic BP. Visit-to-visit BP variability may be associated with the risk of heart failure early in the life course and thus may be reflected in subclinical alterations in cardiac structure and function.

Objective

To evaluate the association between visit-to-visit BP variability in early adulthood and myocardial structure and function in middle age.

Design, Setting, and Participants

This cohort study used data from the Coronary Artery Risk Development in Young Adults (CARDIA) study, a community-based cohort study of 5115 participants aged 18 to 30 years at baseline (year 0; March 25, 1985, to June 7, 1986) and followed up over a 30-year interval. A total of 2400 CARDIA study participants underwent evaluation at 4 field sites (Birmingham, Alabama; Oakland, California; Chicago, Illinois; and Minneapolis, Minnesota). Blood pressure was measured at 8 visits over a 25-year interval and participants received echocardiograms at year 25 (June 1, 2010, to August 31, 2011). Data analysis was conducted from June 7, 1986, to August 31, 2011.

Exposures

Visit-to-visit systolic and diastolic BP variability measures included SD, average real variability, and variability independent of the mean.

Main Outcomes and Measures

Echocardiographic indices of myocardial structure, systolic function, and diastolic function at the year 25 examination.

Results

Of the 2400 participants, 1024 were men (42.7%) and 976 were African American (40.7%); mean (SD) age at the year 25 examination was 50.4 (3.6) years. Per 1-SD increment, greater visit-to-visit systolic BP variability independent of the mean was associated with higher left-ventricular (LV) mass index (β [SE], 2.66 [0.4] g/m2, P < .001), worse diastolic function (early peak diastolic mitral annular velocity [é]) (β [SE], -0.40 [0.1] cm/s, P < .001), higher LV filling pressures (mitral inflow velocity to early diastolic mitral annular velocity [E/é]) β [SE], 0.37 [0.1] cm/s, P < .001), and worse global longitudinal strain (β [SE], 0.17 [0.1], P = .002). Similarly, greater visit-to-visit diastolic BP variability was associated with higher LV mass index (β [SE], 3.21 [0.5] g/m2, P < .001), worse diastolic function (é: β [SE], -0.24 [0.1] cm/s [P < .001]; E/é: β [SE], 0.23 [0.1] cm/s [P < .001]), and worse global longitudinal strain (β [SE], 0.13 [0.1], P = .02). The findings remained consistent when other BP variability measures were used (SD and average real variability).

Conclusions and Relevance

In this cohort study using data from the CARDIA study, greater visit-to-visit systolic and diastolic BP variability have been associated with adverse alterations in cardiac structure as well as systolic and diastolic function independent of mean BP levels.

Changes in the inspiratory pattern contribute to modulate the sympathetic activity in sino-aortic denervated rats

NEW FINDINGS

What is the central question of this study? Sino-aortic denervated (SAD) rats present normal levels of sympathetic activity and mean arterial pressure. However, neural mechanisms regulating the sympathetic activity in the absence of arterial baroreceptors remain unclear. Considering that respiration modulates the sympathetic activity, we hypothesize that changes in the respiratory network contribute to keep the sympathetic outflow in the normal range after removal of arterial baroreceptors. What is the main finding and its importance? Despite longer inspiration observed in SAD rats, the respiratory-sympathetic coupling is working within a normal range of variation. These findings suggest that in the absence of arterial baroreceptors the respiratory modulation of sympathetic activity is maintained within the normal range. The activity of presympathetic neurons is under respiratory modulation, and changes in the central respiratory network may impact on the baseline sympathetic activity and mean arterial pressure. It is well known that after removal of baroreceptor afferents [sino-aortic denervation (SAD)], rats present an unexpected normal level of mean arterial pressure. We hypothesized that changes in the respiratory pattern and in the respiratory modulation of the sympathetic activity contribute to keep the sympathetic outflow within a normal range of variation in the absence of arterial baroreceptors in rats. To study these mechanisms, we recorded perfusion pressure and the activities of phrenic and thoracic sympathetic nerves in male juvenile rats using the working heart-brainstem preparation. The time of inspiration significantly increased in SAD rats, and this change was not dependent on the carotid bodies or on the vagal afferents. However, no changes were observed in the perfusion pressure or in the baseline thoracic sympathetic nerves in all phases of the respiratory cycle in SAD rats. Our data show that despite longer inspiratory activity, the baseline sympathetic activity is maintained at a normal level in SAD rats. These findings indicate that the respiratory-sympathetic coupling is normal after SAD and suggest that the respiratory modulation of sympathetic activity is maintained within the normal range after the removal of arterial baroreceptors.