The Labdane Ent-3-Acetoxy-Labda-8(17), 13-Dien-15-Oic Decreases Blood Pressure In Hypertensive Rats

Abstract Background: Labdane-type diterpenes induce lower blood pressure via relaxation of vascular smooth muscle; however, there are no studies describing the effects of labdanes in hypertensive rats. Objective: The present study was designed to investigate the cardiovascular actions of the labdane-type diterpene ent-3-acetoxy-labda-8(17), 13-dien-15-oic acid (labda-15-oic acid) in two-kidney 1 clip (2K-1C) renal hypertension. Methods: Vascular reactivity experiments were performed in aortic rings isolated from 2K-1C and normotensive (2K) male Wistar rats. Nitrate/nitrite (NOx) measurement was performed in aortas by colorimetric assay. Blood pressure measurements were performed in conscious rats. Results: Labda-15-oic acid (0.1-300 µmol/l) and forskolin (0.1 nmol/l - 1 µmol/l) relaxed endothelium-intact and endothelium-denuded aortas from both 2K-1C and 2K rats. Labda-15-oic acid was more effective at inducing relaxation in endothelium-intact aortas from 2K pre-contracted with phenylephrine when compared to the endothelium-denuded ones. Forskolin was more potent than labda-15-oic acid at inducing vascular relaxation in arteries from both 2K and 2K-1C rats. Labda-15-oic acid-induced increase in NOx levels was lower in arteries from 2K-1C rats when compared to 2K rats. Intravenous administration of labda-15-oic acid (0.3-3 mg/kg) or forskolin (0.1-1 mg/kg) induced hypotension in conscious 2K-1C and 2K rats. Conclusion: The present findings show that labda-15-oic acid induces vascular relaxation and hypotension in hypertensive rats.

Acute Effects of Exercise on Blood Pressure: A Meta-Analytic Investigation

Abstract Hypertension affects 25% of the world's population and is considered a risk factor for cardiovascular disorders and other diseases. The aim of this study was to examine the evidence regarding the acute effect of exercise on blood pressure (BP) using meta-analytic measures. Sixty-five studies were compared using effect sizes (ES), and heterogeneity and Z tests to determine whether the ES were different from zero. The mean corrected global ES for exercise conditions were -0.56 (-4.80 mmHg) for systolic BP (sBP) and -0.44 (-3.19 mmHg) for diastolic BP (dBP; z ≠ 0 for all; p < 0.05). The reduction in BP was significant regardless of the participant's initial BP level, gender, physical activity level, antihypertensive drug intake, type of BP measurement, time of day in which the BP was measured, type of exercise performed, and exercise training program (p < 0.05 for all). ANOVA tests revealed that BP reductions were greater if participants were males, not receiving antihypertensive medication, physically active, and if the exercise performed was jogging. A significant inverse correlation was found between age and BP ES, body mass index (BMI) and sBP ES, duration of the exercise's session and sBP ES, and between the number of sets performed in the resistance exercise program and sBP ES (p < 0.05). Regardless of the characteristics of the participants and exercise, there was a reduction in BP in the hours following an exercise session. However, the hypotensive effect was greater when the exercise was performed as a preventive strategy in those physically active and without antihypertensive medication.

Ambulatory Blood Pressure Monitoring: Five Decades of More Light and Less Shadows

Abstract Casual blood pressure measurements have been extensively questioned over the last five decades. A significant percentage of patients have different blood pressure readings when examined in the office or outside it. For this reason, a change in the paradigm of the best manner to assess blood pressure has been observed. The method that has been most widely used is the Ambulatory Blood Pressure Monitoring - ABPM. The method allows recording blood pressure measures in 24 hours and evaluating various parameters such as mean BP, pressure loads, areas under the curve, variations between daytime and nighttime, pulse pressure variability etc. Blood pressure measurements obtained by ABPM are better correlated, for example, with the risks of hypertension. The main indications for ABPM are: suspected white coat hypertension and masked hypertension, evaluation of the efficacy of the antihypertensive therapy in 24 hours, and evaluation of symptoms. There is increasing evidence that the use of ABPM has contributed to the assessment of blood pressure behaviors, establishment of diagnoses, prognosis and the efficacy of antihypertensive therapy. There is no doubt that the study of 24-hour blood pressure behavior and its variations by ABPM has brought more light and less darkness to the field, which justifies the title of this review.

Renal sodium handling and nighttime blood pressure.

Blood pressure follows a circadian rhythm with a physiologic 10% to 20% decrease during the night. There is now increasing evidence that a blunted decrease or an increase in nighttime blood pressure is associated with a greater prevalence of target organ damage and a faster disease progression in patients with chronic kidney diseases. Several factors contribute to the changes in nighttime blood pressure including changes in hormonal profiles such as variations in the activity of the renin-angiotensin and the sympathetic nervous systems. Recently, it was hypothesized that the absence of a blood pressure decrease during the nighttime (nondipping) is in fact a pressure-natriuresis mechanism enabling subjects with an impaired capacity to excrete sodium to remain in sodium balance. In this article, we review the clinical and epidemiologic data that tend to support this hypothesis. Moreover, we show that most, if not all, clinical conditions associated with an impaired dipping profile are diseases associated either with a low glomerular filtration rate and/or an impaired ability to excrete sodium. These observations would suggest that renal function, and most importantly the ability to eliminate sodium during the day, is indeed a key determinant of the circadian rhythm of blood pressure.

Ambulatory blood pressure monitoring in adolescent untreated hypertensive patients.

Ambulatory blood pressure profiles were obtained with the portable semi-automatic blood pressure recorder Remler M2000 in groups of 20 adolescents, 20 young and 20 middle-aged adults and 20 elderly untreated patients, all considered by their physician to be hypertensive. It was found that adolescents who are hypertensive when seeing their physician are more often normotensive outside the physician's office than adult and elderly patients under similar conditions. The increased heart rate variability which was detected in adolescents was not associated with an enhanced blood pressure variability.

Ambulatory blood pressure measurement and antihypertensive therapy.

The traditional basis for assessing the effect of antihypertensive therapy is the blood pressure reading taken by a physician. However, several recent trials have been designed to evaluate the blood pressure lowering effect of various therapeutic agents during the patients' normal daytime activities, using a portable, semi-automatic blood pressure recorder. The results have shown that in a given patient, blood pressure measured at the physician's office often differs greatly from that prevailing during the rest of the day. This is true both in treated and untreated hypertensive patients. The difference between office and ambulatory recorded pressures cannot be predicted from blood pressure levels measured by the physician. Therefore, a prospective study was carried out in patients with diastolic blood pressures that were uncontrolled at the physician's office despite antihypertensive therapy. The purpose was to evaluate the response of recorded ambulatory blood pressure to treatment adjustments aimed at reducing office blood pressure below a pre-set target level. Only patients with high ambulatory blood pressures at the outset appeared to benefit from further changes in therapy. Thus, ambulatory blood pressure monitoring can be used to identify those patients who remain hypertensive only when facing the physician, despite antihypertensive therapy. Ambulatory monitoring could thus help to evaluate the efficacy of antihypertensive therapy and allow individual treatment.

Elevated blood pressure prevalence in children did not follow the increase in overweight: results from a school-based study in a rapidly developing country, 1998-2006

Background: Blood pressure (BP) is strongly associated with body weight and there is concern that the pediatric overweight epidemic could lead to an increase in children's mean BP. Objectives: We analyzed BP trends from 1998 to 2006 among children of the Seychelles, a rapidly developing middle-income country in Africa. Methods: Serial school-based surveys of weight, height and BP were conducted yearly between 1998-2006 among all students of the country in four school grades (kindergarten, 4th, 7th and 10th years of compulsory school). We used the CDC criteria to define "overweight" (BMI _95th sex-, and age-specific percentile) and the NHBPEP criteria for "elevated BP" (BP _95th sex-, age-, and height specific percentile). Methods for height, weight, and BP measurements were identical over the study period. The trends in mean BMI and mean systolic/diastolic BP were assessed with linear regression. Results: 27,703 children aged 4-18 years (participation rate: 79%) contributed 43,927 observations on weight, height, and BP. The prevalence of overweight increased from 5.1% in 1998-2000 to 8.1% in 2004-2006 among boys, and from 6.1% to 9.1% among girls, respectively. The prevalence of elevated BP was 8.4% in 1998-2000 and 6.9% in 2004-2006 among boys; 9.8% and 7.8% among girls, respectively. Over the 9-years study period, age-adjusted body mass index (BMI) increased by 0.078 kg/m2/year in boys and by 0.083 kg/m2/year in girls (both sexes, P_0.001). Age- and height-adjusted systolic BP decreased by -0.37 mmHg/year in boys and by -0.34 mmHg/year in girls (both sexes, P_0.001). Diastolic BP did not change in boys (-0.02 mmHg/year, P: 0.40) and slightly increased in girls (0.07 mmHg/year, P: 0.003). These trend estimates were altered modestly upon further adjustment for BMI or if analyses were based on median rather than mean values. Conclusion: Although body weight increased markedly between 1998 and 2006 in this population, systolic BP decreased and diastolic BP changed only marginally. This suggests that population increases in body weight are not necessarily associated with corresponding rises in BP in children.

Inflammatory markers and blood pressure: sex differences and the effect of fat mass in the CoLaus Study.

Several studies have reported high levels of inflammatory biomarkers in hypertension, but data coming from the general population are sparse, and sex differences have been little explored. The CoLaus Study is a cross-sectional examination survey in a random sample of 6067 Caucasians aged 35-75 years in Lausanne, Switzerland. Blood pressure (BP) was assessed using a validated oscillometric device. Anthropometric parameters were also measured, including body composition, using electrical bioimpedance. Crude serum levels of interleukin-6 (IL-6), tumor necrosis factor α (TNF-α) and ultrasensitive C-reactive protein (hsCRP) were positively and IL-1β (IL-1β) negatively (P<0.001 for all values), associated with BP. For IL-6, IL-1β and TNF-α, the association disappeared in multivariable analysis, largely explained by differences in age and body mass index, in particular fat mass. On the contrary, hsCRP remained independently and positively associated with systolic (β (95% confidence interval): 1.15 (0.64; 1.65); P<0.001) and diastolic (0.75 (0.42; 1.08); P<0.001) BP. Relationships of hsCRP, IL-6 and TNF-α with BP tended to be stronger in women than in men, partly related to the difference in fat mass, yet the interaction between sex and IL-6 persisted after correction for all tested confounders. In the general population, the associations between inflammatory biomarkers and rising levels of BP are mainly driven by age and fat mass. The stronger associations in women suggest that sex differences might exist in the complex interplay between BP and inflammation.

Regulation of blood pressure and renal function by NCC and ENaC: lessons from genetically engineered mice.

The activity of the thiazide-sensitive Na(+)/Cl(-) cotransporter (NCC) and of the amiloride-sensitive epithelial Na(+) channel (ENaC) is pivotal for blood pressure regulation. NCC is responsible for Na(+) reabsorption in the distal convoluted tubule (DCT) of the nephron, while ENaC reabsorbs the filtered Na(+) in the late DCT and in the cortical collecting ducts (CCD) providing the final renal adjustment to Na(+) balance. Here, we aim to highlight the recent advances made using transgenic mouse models towards the understanding of the regulation of NCC and ENaC function relevant to the control of sodium balance and blood pressure. We thus like to pave the way for common mechanisms regulating these two sodium-transporting proteins and their potential implication in structural remodeling of the nephron segments and Na(+) and Cl(-) reabsorption.

Cholestérol, pression artérielle et fumée de cigarette dans la population en Suisse: le projet MONICA. [Cholesterol, blood-pressure and cigarette-smoking in switzerland - the MONICA-project].

Elevated plasma cholesterol, high blood pressure and cigarette smoking are three major risk factors for coronary heart disease. Within the framework of Switzerland's participation in the multicenter study MONICA (MONItoring of trends and determinants in CArdiovascular disease), proposed by the WHO, a first risk factor survey was conducted in a representative sample of the population (25-74 years) of two reporting units (cantons of Vaud and Fribourg, canton of Tessin). A high blood cholesterol level (>6,7 mmol/l) is the most common risk factor for coronary heart disease among the studied population. Among men, about 13% have elevated blood pressure, the proportion being about one in ten among women; these proportions increase with age and are slightly above these values in Tessin. Cigarette smoking is still a common behavior; between 25 and 45 years one third of the population (male and female) regularly smoke cigarettes.

Blood pressure change and outcome in acute ischemic stroke: the impact of baseline values, previous hypertensive disease and previous antihypertensive treatment.

BACKGROUND: Management of blood pressure (BP) in acute ischemic stroke is controversial. The present study aims to explore the association between baseline BP levels and BP change and outcome in the overall stroke population and in specific subgroups with regard to the presence of arterial hypertensive disease and prior antihypertensive treatment. METHODS: All patients registered in the Acute STroke Registry and Analysis of Lausanne (ASTRAL) between 2003 and 2009 were analyzed. Unfavorable outcome was defined as modified Rankin score more than 2. A local polynomial surface algorithm was used to assess the effect of BP values on outcome in the overall population and in predefined subgroups. RESULTS: Up to a certain point, as initial BP was increasing, optimal outcome was seen with a progressively more substantial BP decrease over the next 24-48 h. Patients without hypertensive disease and an initially low BP seemed to benefit from an increase of BP. In patients with hypertensive disease, initial BP and its subsequent changes seemed to have less influence on clinical outcome. Patients who were previously treated with antihypertensives did not tolerate initially low BPs well. CONCLUSION: Optimal outcome in acute ischemic stroke may be determined not only by initial BP levels but also by the direction and magnitude of associated BP change over the first 24-48 h.