Effects of Mechanical Forces on Signal Transduction and Gene Expression in Endothelial Cells
Fluid shear stress and circumferential stretch play important roles in maintaining the homeostasis of the blood vessel, and they can also be pathophysiological factors in cardiovascular diseases such as atherosclerosis and hypertension. Some of the effects of mechanical strain on endothelial cells are similar to those by shear stress, eg, the signaling pathways and the genes activated, but there are differences, eg, the time course of the responses. Studies on the effects of mechanical forces on signal transduction and gene expression provide insights into the molecular mechanisms by which hemodynamic factors regulate vascular physiology and pathophysiology.
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Recent Progress in Angiotensin II Type 2 Receptor Research in the Cardiovascular System
Angiotensin II (Ang II) plays an important role in regulating cardiovascular hemodynamics and structure. Multiple lines of evidence have suggested the existence of Ang II receptor subtypes, and at least 2 distinct receptor subtypes have been defined on the basis of their differential pharmacological and biochemical properties and designated as type 1 (AT1) and type 2 (AT2) receptors. To date, most of the known effects of Ang II in adult tissues are attributable to the AT1 receptor. Recent cloning of the AT2 receptor contributes to reveal its physiological functions, but many functions of the AT2 receptor are still an enigma. AT1 and AT2 receptors belong to the 7-transmembrane, G protein�coupled receptor family. However, accumulating evidence demonstrates that the function and signaling mechanisms of these receptor subtypes are quite different, and these receptors may exert opposite effects in terms of cell growth and blood pressure regulation. We will review the role of the AT2 receptor in the cardiovascular system and the molecular and cellular mechanisms of AT2 receptor action.
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Measuring Forearm Blood Flow and Interpreting the Responses to Drugs and Mediators
Venous occlusion plethysmography has been widely used to study forearm blood flow. The principle of the technique is straightforward: the rate of swelling of the forearm during occlusion of venous return is used to assess the rate of arterial inflow. This article describes venous occlusion plethysmography, discusses the presentation and analysis of data (dose of drug or concentration? forearm blood flow or resistance?), and highlights certain potential problems and limitations of the technique as a means of studying disease states.
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Tissue Angiotensin and Pathobiology of Vascular Disease
There is increasing evidence that direct pathobiological events in the vessel wall play an important role in vascular disease. In this article, we propose a model that unifies the interrelationship among cardiovascular risk factors, angiotensin II, and the pathobiological mechanisms contributing to cardiovascular disease. This model may also explain the beneficial effects of ACE inhibitors on cardiovascular events beyond blood pressure reduction.
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Two-Week Administration of Tempol Attenuates Both Hypertension and Renal Excretion of 8-Iso Prostaglandin
The present study was designed to test whether prolonged administration of tempol ameliorates oxidative stress and hypertension in SHR. In conclusion, the SHR is a model of hypertension and renal vasoconstriction associated with oxidative stress. Because long-term administration of a superoxide scavenger reduces blood pressure and oxidative stress in vivo, this study suggests a role for oxygen radicals in the maintenance of hypertension in SHR.
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Aortic Pulse Wave Velocity as a Marker of Cardiovascular Risk in Hypertensive Patients
Large artery damage is a major contributory factor to cardiovascular morbidity and mortality of patients with hypertension. Pulse wave velocity (PWV), a classic evaluation of arterial distensibility, has never been ascertained as a cardiovascular risk marker. To determine the factors influencing aortic PWV and the potential predictor role of this measurement, we studied a cohort of 710 patients with essential hypertension. This study shows that aortic PWV is strongly associated with the presence and extent of atherosclerosis and constitutes a forceful marker and predictor of cardiovascular risk in hypertensive patients.
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Normalization of Blood Pressure and Renal Vascular Resistance in SHR With a Membrane-Permeable Superoxide Dismutase Mimetic
Superoxide radical (O2-) is increased in the vessel wall of spontaneously hypertensive rats (SHR) where its blockade potentiates endothelium-dependent vasodilation. The purpose of this study was to determine the role of O2- in the hypertension and renal vasoconstriction of SHR and its interaction with nitric oxide (NO). The antihypertensive action of tempol depends on NO synthesis presumably because O2- inactivates NO and thus diminishes its vasodilatory actions.
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Role of NADH/NADPH Oxidase�Derived H2O2 in Angiotensin II�Induced Vascular Hypertrophy
Recent evidence suggests that oxidative mechanisms may be involved in vascular smooth muscle cell (VSMC) hypertrophy. We previously showed that angiotensin II (Ang II) increases superoxide production by activating an NADH/NADPH oxidase, which contributes to hypertrophy. These data indicate that AT1 receptor�mediated production of superoxide generated by the NADH/NADPH oxidase is followed by an increase in intracellular H2O2, suggesting a specific role for these oxygen species and scavenging systems in modifying the intracellular redox state in vascular growth.
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A Predictor of Long-term Cardiovascular Mortality in a French Male Population
Studies on the usefulness of blood pressure as a prognostic factor in cardiovascular disease have more often involved investigations of the levels of diastolic or systolic blood pressure. However, blood pressure may be divided into two other components: steady (mean pressure) and pulsatile (pulse pressure). In this study, the relationship of pulse pressure to cardiovascular mortality was investigated in 19 083 men 40 to 69 years old who were undergoing a routine systematic health examination and were being followed up after a mean period of 19.5 years.
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A Noninvasive Computerized Tail-Cuff System for Measuring Blood Pressure in Mice
We have validated a noninvasive computerized tail-cuff system for measuring blood pressure in mice. The system was designed to perform all functions automatically, including a programmable routine of cuff inflation and deflation, analysis and assignment of pulse rate and blood pressure, and recording of data electronically. These data show that blood pressures measured on trained mice by a computerized noninvasive tail-cuff system are reproducible and correlate well with intra-arterial blood pressures measured on unrestrained, unanesthetized mice.
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Comparison of finger and intra-arterial blood pressure monitoring at rest and during laboratory testing
The accuracy of blood pressure values obtained by continuous noninvasive finger blood pressure recording via the FINAPRES device was evaluated by comparison with simultaneous intraarterial monitoring both at rest and during performance of tests known to induce fast and often marked changes in blood pressure. The comparison was performed in 24 normotensive or essential hypertensive subjects.
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Ambulatory blood pressure. An independent predictor of prognosis in essential hypertension
To determine the prognostic significance of ambulatory blood pressure, we prospectively followed for up to 7.5 years (mean, 3.2) 1187 subjects with essential hypertension and 205 healthy normotensive control subjects who had baseline off-therapy 24-hour noninvasive ambulatory blood pressure monitoring. Our findings suggest that ambulatory blood pressures stratifies cardiovascular risk in essential hypertension independent of clinic blood pressure and other traditional risk markers including echocardiographic left ventricular hypertrophy.
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Trends in the Prevalence, Awareness, Treatment, and Control of Hypertension in the Adult US Population
The objective of this study was to describe secular trends in the distribution of blood pressure and prevalence of hypertension in US adults and changes in rates of awareness, treatment, and control of hypertension. The study design comprised nationally representative cross-sectional surveys with both an in-person interview and a medical examination that included blood pressure measurement. Hypertension awareness, treatment, and control also have improved tremendously during the same period, accounting for much of the shift at the upper end of the distribution. Despite these favorable trends, many people with hypertension are unaware of their condition, and many more are untreated or inadequately treated.
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Aortic Stiffness Is an Independent Predictor of All-Cause and Cardiovascular Mortality in Hypertension
Although various studies reported that pulse pressure, an indirect index of arterial stiffening, was an independent risk factor for mortality, a direct relationship between arterial stiffness and all-cause and cardiovascular mortality remained to be established in patients with essential hypertension. This study provides the first direct evidence that aortic stiffness is an independent predictor of all-cause and cardiovascular mortality in patients with essential hypertension.
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