Helix Exams: Hypertension

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Hypertension

Definition of Hypertension

Hypertension is an abnormal elevation of systolic or diastolic arterial pressure. Systolic hypertension is generally related to emotional stress, sclerosis of the aorta and large arteries, or aortic insufficiency. Diastolic hypertension may result from obscure causes (essential), renal disease, or endocrine disorders.

Aging Progressively Impairs Endothelium-Dependent Vasodilation in Forearm Resistance Vessels of Humans Studies in experimental models suggest that endothelium-derived nitric oxide is reduced with aging, and this circumstance may be relevant to atherogenesis. The aim of this study was to determine whether increasing age resulted in altered endothelium-dependent vasodilation in the forearm resistance vessels of healthy humans. Forearm blood flow was measured in 119 healthy subjects, aged 19 to 69 years, by venous occlusion plethysmography. Read the Article
Arterial Calcifications, Arterial Stiffness, and Cardiovascular Risk in End-Stage Renal Disease To test the predictive values of and independent contributions to cardiovascular and all-cause mortality of various arterial parameters exploring characteristics of the arterial wall at different sites, we studied prospectively 110 stable end-stage renal disease patients on hemodialysis. These parameters involved carotid diameter, carotid intima-media thickness, carotid compliance, carotid distensibility, carotid incremental elastic modulus, aortic diameter, aortic pulse wave velocity, and the presence of arterial calcifications measured at the sites of the carotid artery, abdominal aorta, iliofemoral axis, and legs. The results of this study showed that the presence and extent of vascular calcifications were strong predictors of cardiovascular and all-cause mortality. Carotid incremental elastic modulus gave additional predictive value. Read the Article
AT2 Receptor Stimulation Increases Aortic Cyclic GMP in SHRSP by a Kinin-Dependent Mechanism In the present study we tested the hypothesis whether an angiotensin AT2 receptor-mediated stimulation of the bradykinin (BK)/nitric oxide (NO) system can account for the effects of AT1 receptor antagonism on aortic cGMP described previously in SHRSP. The effects of ANG II and of losartan plus ANG II on aortic cGMP content were both blocked by cotreatment with the AT2 receptor antagonist PD 123319. Read the Article
Mineralocorticoid Blockade Reduces Vascular Injury in Stroke-Prone Hypertensive Rats Chronic treatment of saline-drinking stroke-prone spontaneously hypertensive rats (SHRSP) with agents that interfere with the formation or actions of angiotensin II (Ang II) prevents the development of stroke and renal vascular damage. In both studies, histopathologic examination revealed a marked protective effect of spironolactone against the development of malignant nephrosclerotic and cerebrovascular lesions. These observations indicate a vascular and end organ protective effect of spironolactone in the absence of lowered blood pressure in saline-drinking SHRSP and are consistent with a major role for mineralocorticoids as hormonal mediators of vascular injury. Read the Article
Assessment of Arterial Distensibility by Automatic Pulse Wave Velocity Measurement Pulse wave velocity is widely used as an index of arterial distensibility. The aim of this study was to evaluate the accuracy of a new automatic device to measure it and then to analyze the major determinants of pulse wave velocity by application of this device in a large population. We evaluated the accuracy of on-line and computerized measurement of pulse wave velocity using an algorithm based on the time-shifted and repeated linear correlation calculation between the initial rise in pressure waveforms compared with the reference method (manual calculation) in 56 subjects. Read the Article
Superiority of Brain Natriuretic Peptide as a Hormonal Marker of Ventricular Systolic and Diastolic Atrial and brain natriuretic peptides (ANP and BNP) are produced by the heart, and their plasma concentrations are increased in human chronic congestive heart failure. Although separate studies have suggested that circulating levels of the biologically active C-terminal ANP, the biologically inactive N-terminal ANP, and BNP may have diagnostic utility in the detection of left ventricular systolic dysfunction or left ventricular hypertrophy, no studies have directly assessed the relative value of these peptides prospectively. We therefore designed this study to compare the relative ability of the different natriuretic peptides to detect abnormal left ventricular systolic and diastolic function and left ventricular hypertrophy. Read the Article
Growth Factors and Mitogen-Activated Protein Kinases Mammalian cells respond to external stimuli by activation of a variety of signal transduction pathways, which culminate in stereotypical responses, such as proliferation, growth arrest, hypertrophy, differentiation, or apoptosis. In vertebrates the actions of many stimuli resulting in proliferative or hypertrophic growth converge on a set of cellular kinase cascades, which are collectively called the mitogen-activated protein (MAP) kinase cascades. These MAP kinases have been implicated in vascular smooth muscle cell proliferation and hypertrophy, responses that are central to the pathophysiology of hypertension. In this review, we will examine how proliferative and hypertrophic stimuli activate these MAP kinase cascades, what are the consequences of that activation on gene expression, and how do these signals drive the cell into one of the stereotypical responses noted above. Read the Article
In Vivo Evidence for Microvascular Oxidative Stress in Spontaneously Hypertensive Rats The factors that predispose to the accelerated organ injury that accompanies the hypertensive syndrome have remained speculative and without a firm experimental basis. Indirect evidence has suggested that a key feature may be related to an enhanced oxygen radical production. The purpose of this study was to refine and use a technique to visualize evidence of spontaneous microvascular oxidative stress in vivo in the spontaneously hypertensive rat (SHR) compared with its normotensive control, the Wistar-Kyoto rat (WKY). We investigated the effects of adrenal glucocorticoids on the microvascular oxidative stress sequence. Read the Article
Role of p47phox in Vascular Oxidative Stress and Hypertension Caused by Angiotensin II Hypertension caused by angiotensin II is dependent on vascular superoxide (O2�-) production. The nicotinamide adenine dinucleotide phosphate (NAD[P]H) oxidase is a major source of vascular O2�- and is activated by angiotensin II in vitro. However, its role in angiotensin II-induced hypertension in vivo is less clear. In the present studies, we used mice deficient in p47phox, a cytosolic subunit of the NADPH oxidase, to study the role of this enzyme system in vivo. Read the Article
Hypertension and the Pathogenesis of Atherosclerosis Hypertension is a risk factor for the development of atherosclerosis, although the mechanisms have not been well elucidated. This article reviews evidence that leads to the postulate that hypertension predisposes to and accelerates atherosclerosis at least in part because of synergy between elevated blood pressure and other atherogenic stimuli to induce oxidative stress on the arterial wall. Read the Article
Evidence for a Gene Influencing Blood Pressure on Chromosome 17 Hypertension is a leading cause of morbidity and mortality. Efforts to identify hypertension genes have focused on 3 approaches: mendelian disorders, candidate genes, and genome-wide scans. Thus far, these efforts have not identified genes that contribute substantively to overall blood pressure (BP) variation in the community. Such knowledge could extend our understanding of the genetic basis of essential hypertension and have implications for the evaluation and treatment of patients with high BP. Read the Article
Influence of Dietary Sodium Intake on Renal Medullary Nitric Oxide Synthase We previously reported that chronic systemic treatment of rats with a nitric oxide synthase inhibitor leads to a selective decrease in renal medullary blood flow, retention of sodium, and the development of hypertension. In the present studies, we used protein blotting techniques to determine the whole tissue distribution and relative quantitation of the different nitric oxide synthase isoforms in the renal cortex and medulla of Sprague-Dawley rats maintained on a low (0.4% NaCl) or high (4.0% NaCl) dietary salt intake. Read the Article
Chronic Leptin Infusion Increases Arterial Pressure Plasma leptin concentration is increased in hypertensive obese humans, but whether leptin contributes to the increased arterial pressure in obesity is not known. In this study, we tested whether chronic increases in leptin, to levels comparable to those in obesity, could cause a sustained increase in arterial pressure and also the importance of central nervous system (CNS) versus systemic mechanisms. Five male Sprague-Dawley rats were implanted with chronic nonoccluding catheters in the abdominal aorta and both carotid arteries for CNS infusion, and five other rats were implanted with an abdominal aorta catheter and femoral vein catheter for intravenous (IV) infusion. Read the Article
Aortic Stiffness Is an Independent Predictor of Primary Coronary Events in Hypertensive Patients Arterial stiffness may predict coronary heart disease beyond classic risk factors. In a longitudinal study, we assessed the predictive value of arterial stiffness on coronary heart disease in patients with essential hypertension and without known clinical cardiovascular disease. This study provides the first direct evidence in a longitudinal study that aortic stiffness is an independent predictor of primary coronary events in patients with essential hypertension. Read the Article
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