Search Results
Results 601 - 650 of 1822
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Cleophas T J - - 2002
BACKGROUND: Baroreflex sensitivity declines with age, creating a fall in systolic blood pressure and pulse pressure when standing. If, in addition, blood pressure is reduced as a result of antihypertensive medication, compensatory mechanisms may be inadequate and orthostatic problems may occur. This may be less true in patients on beta-blockers. ...
Eckhart Andrea D - - 2002
Cardiovascular regulation is tightly controlled by signaling through G protein-coupled receptors (GPCRs). beta-Adrenergic receptors (ARs) are GPCRs that regulate inotropy and chronotropy in the heart and mediate vasodilation, which critically influences systemic vascular resistance. GPCR kinases (GRKs), including GRK2 (or betaARK1), phosphorylate and desensitize agonist-activated betaARs. Myocardial GRK2 levels are ...
van Baak Marleen A - - 2002
OBJECTIVE: Our objective was to investigate the thermogenic efficacy of single oral doses of the novel beta(3)-adrenergic receptor agonist L-796568 [(R )-N -[4-[2-[[2-hydroxy-2-(3-pyridinyl)ethyl]amino]ethyl]-phenyl]-4-[4-[4-(trifluoromethyl)phenyl]thiazol-2-yl]-benzenesulfonamide, dihydrochloride] in humans. METHODS: Twelve healthy overweight to obese men participated in this 2-center, 3-period, randomized, placebo-controlled, crossover trial. In each period subjects received 250 mg L-796568, ...
Hassanzadeh M - - 2002
The present study was carried out to determine, first, the cardiac beta-adrenergic receptor characteristics of broiler chick embryos exposed to two different CO(2) levels during the last stage of embryonic development, and second, the prophylactic effect of beta(1)-adrenoceptor blocker on right ventricular hypertrophy in broiler chickens. High CO(2) embryos showed ...
Bagi Per - - 2002
The urethral response to a sudden forced dilation was studied in ten healthy male volunteers aged from 27 to 71 years. Measurements were performed from the bladder neck and beyond the region of high pressure using a specially designed probe. The pressure response after dilation showed a characteristic course, which ...
Bagi Per - - 2002
The significance of the anatomical location and age on the urethral response to a sudden forced dilation was studied in 30 healthy males aged 23-85 years. The pressure decay after dilation was fitted with a double exponential function of the form: P(t) = P(equ) + P(alpha)e(-t/tau(alpha) + P(beta)e(t/tau(beta) where P(t) ...
Szabó Gábor - - 2002
BACKGROUND: This study investigated the changes of catecholamine responsiveness and beta-adrenergic receptor/adenylyl cyclase pathway during acute cardiac transplant rejection. METHODS: Isogeneic Lewis to Lewis and allogeneic Dark Agouti (DA) to Lewis rat cardiac transplants were studied 3 and 5 days after heterotopic intraabdominal transplantation (n=6/group). Myocardial blood flow (MBF), left ...
Badorff Cornel - - 2002
Congestive heart failure is a leading cause of mortality in developed countries. Myocardial hypertrophy resulting from hypertension often precedes heart failure. Understanding the signaling underlying cardiac hypertrophy and failure is of major interest. Here, we identified Fas receptor activation, a classical death signal causing apoptosis via activation of the caspase ...
Schiffrin Ernesto L - - 2002
In a previous retrospective study, long-term treatment of essential hypertensive patients with a slow-release calcium channel blocker resulted in normal resistance artery structure and endothelial function, which did not occur with a beta-blocker. In the present prospective study, 19 previously untreated essential hypertensive patients (aged 47 +/- 2 years, 75% ...
Chung Peter C H - - 2002
PURPOSE: To report a case of pheochromocytoma exhibiting an increase in systemic vascular resistance index (SVRI) and decreased cardiac index (CI) after use of labetalol. CLINICAL FEATURES: A 36-yr-old male underwent adrenectomy for pheochromocytoma. Midazolam 5 mg, fentanyl 100 microg and labetalol 20 mg were administrated intravenously for premedication upon ...
Schiffrin Ernesto L - - 2002
BACKGROUND: Treatment of essential hypertensive patients with an AT1 angiotensin receptor antagonist has previously resulted in correction of resistance artery structure and endothelial function, whereas in a parallel group treated with the beta-blocker atenolol there was no improvement of altered vascular structure and function. To test the hypothesis that patients ...
Moniotte Stéphane - - 2002
Recently, a functional, negatively inotropic, beta(3)-adrenoceptor was characterized in the human heart. Several studies now suggest that this receptor might play an important role in the pathophysiology of heart failure, by counterbalancing the effects of a beta(1)- and beta(2)-stimulation. Therefore, this review summarizes the rationale and effects of beta-adrenergic blockade ...
Heusser K - - 2002
BACKGROUND: Celiprolol, a newer beta-blocking agent, has been reported to have vasodilatory capacity which may be due to partial beta-2-receptor agonistic activity or to alpha-receptor antagonistic or central sympathoinhibitory effects. METHODS: To more critically assess the physiologic effects of celiprolol, we measured sympathetic nerve activity to muscle (MSNA), forearm blood ...
Takeda Hiroo - - 2002
To investigate the effects of selective beta(2)- and selective beta(3)-adrenoceptor (AR) agonists on prostaglandin (PG) E(2)-induced bladder hyperactivity in conscious free-moving rats. Female Sprague-Dawley rats were anesthetized for implantation of bladder, intravenous, and intra-arterial catheters. The effects of a beta(3)-AR agonist (CL316,243) on cystometric and cardiovascular parameters were assessed in ...
Turner Lexa Rae - - 2002
Iron deficiency (ID) results in ventricular hypertrophy, believed to involve sympathetic stimulation. We hypothesized that with ID 1) intravenous norepinephrine would alter heart rate (HR) and contractility, 2) abdominal aorta would be larger and more distensible, and 3) the beta-blocker propanolol would reduce hypertrophy. 1) 30 CD rats were fed ...
Pessina A C - - 2001
Nebivolol, compared with classical beta-blockers, exerts a high selectivity for beta-adrenergic receptors and also reduces peripheral vascular resistance by modulating nitric oxide (NO) release. This dual mechanism of action leads to effective control of blood pressure at a low degree of beta-blockade and explains the lack of any interference with ...
Tank J - - 2001
Central beta-adrenoreceptors may augment sympathetic outflow. We tested the hypothesis that beta-blockade attenuates central sympathetic outflow by inhibiting central adrenoreceptors. We studied 18 healthy controls (4 female, 14 male; age, 26+/-6 years, body mass index, 23+/-3 kg/m(2)). ECG, brachial, and finger arterial blood pressure, muscle sympathetic nerve activity, and respiration ...
Blanch J - - 2001
Urapidil, a postsynaptic alpha 1 -adrenergic antagonist, has been reported to improve intraoperative hemodynamic stability, although it has never been used to prevent the hemodynamic response of electroconvulsive therapy (ECT). This study was designed to evaluate the clinical effectiveness of urapidil, as an alternative to labetalol, in preventing the hemodynamic ...
Washington B - - 2001
We have shown that chronic treatment with carteolol, a non-selective beta-adrenergic receptor antagonist, improved left ventricular (LV) function and survival in an avian model of dilated cardiomyopathy (DCM). The aim of the present study was to compare ex vivo heart function with and without beta-agonist and antagonist challenge. We investigated ...
Kubo T - - 2001
The purpose of this study was to determine whether carvedilol's alpha(1)-adrenoceptor antagonism persists during long-term therapy of patients with congestive heart failure (CHF). Carvedilol and metoprolol differ in that carvedilol also antagonizes beta(2)- and alpha(1)-adrenoceptors. We hypothesized that in contrast to metoprolol, carvedilol would increase calf vascular conductance (CVC), blunt ...
Mann N S - - 2001
The circadian variation in some biologic functions may have clinical, fiscal and therapeutic implications. The authors discuss circadian variation in portal pressure in cirrhotic patients and nocturnal occurrence of bleeding from varices in these patients. The pathogenesis of the diurnal variation in portal pressure is presented. The authors submit the ...
Wilson K - - 2001
OBJECTIVE: AAA distensibility (Ep, beta) may predict growth and risk of rupture. However, distensibility measurements based on brachial rather than central pressure may be inaccurate. Our aim was to compare AAA distensibility using non-invasive brachial and derived central aortic pressure. DESIGN: brachial and central pressures were measured prospectively by automated ...
Pelat M - - 2001
Pharmacoepidemiological studies have reported an excess of mortality with selegiline, a MAO B inhibitor used in the treatment of Parkinson's disease. The mechanism of this putative adverse effect remains unknown but an interaction with the sympathetic nervous system was suggested. The aim of the present study was to investigate the ...
Antic V - - 2001
We have investigated in rabbits whether overfeeding and weight gain, which lead to hypertension, are associated with changes in circadian rhythm of blood pressure (BP) and heart rate, and whether the sympathetic nervous system is involved in these changes. In adult male rabbits, mean arterial pressure (MAP) and heart rate ...
Cleophas T J - - 2001
If hypertension in patients with diabetes mellitus type II is not adequately controlled by angiotensin-converting enzyme inhibitors (ACE-i), a beta-blocker is frequently added as second-line therapy. Recently, large randomized trials demonstrated the beneficial effect of second-generation dihydropyridine calcium-channel blockers in these patients. These compounds are increasingly being used to replace ...
Harrison L K - - 2001
Cardiovascular activity was measured at resting baseline and in response to a car racing game, undertaken in competition or in cooperation with an experimenter, or individually. Competitiveness and win and goal orientations were assessed by questionnaire. Competition provoked increases in blood pressure and heart rate, and a significant shortening of ...
Ramahi T M - - 2001
Beta blockers improve survival and reduce morbidity of patients with chronic heart failure. Stringent dosing guidelines calling for a 1-hour observation period after initiation or up-titration of beta-blocker therapy might limit the use of beta blockers and increase the expense involved. This study was conducted to determine the usefulness of ...
Møller S - - 2001
BACKGROUND: Patients with cirrhosis exhibit a characteristic hyperdynamic circulation with increased cardiac output and heart rate and reduced systemic vascular resistance. The compliance of the arterial tree has recently been reported to be increased in these patients, who are often treated with beta-blockers, but the effect of this treatment on ...
Mattu G S - - 2001
BACKGROUND: To compare directly the accuracy of the BPM-100(Beta) monitor (an automated oscillometric blood pressure device) with standard auscultatory mercury sphygmomanometry. DESIGN: The BPM-100(Beta) was connected in parallel via a T-tube to a mercury sphygmomanometer. The BPM-100(Beta) and two trained observers (blinded from each other and from the BPM-100(Beta)) measured ...
Guimarães S - - 2001
The total and regional peripheral resistance and capacitance of the vascular system is regulated by the sympathetic nervous system, which influences the vasculature mainly through changes in the release of catecholamines from both the sympathetic nerve terminals and the adrenal medulla. The knowledge of the targets for noradrenaline and adrenaline, ...
Roman B B - - 2001
Studies in human and rodent models have shown that activation of protein kinase C-beta (PKC-beta) is associated with the development of pathological hypertrophy, suggesting that ablation of the PKC-beta pathway might prevent or reverse cardiac hypertrophy. To explore this, we studied mice with targeted disruption of the PKC-beta gene (knockout, ...
Stephens D P - - 2001
We tested for a nonnoradrenergic mechanism of reflex cutaneous vasoconstriction with whole body progressive cooling in seven men. Forearm sites (<1 cm(2)) were pretreated with: 1) yohimbine (Yoh; 5 mM id) to antagonize alpha-adrenergic receptors, 2) Yoh plus propranolol (5 mM Yoh-1 mM PR id) to block alpha- and beta-adrenergic ...
Ramahi T M - - 2001
OBJECTIVES: The purpose of this study was to determine whether higher left ventricular inotropic reserve, defined as the increase in left ventricular ejection fraction (LVEF) in response to intravenous dobutamine infusion, or other ventriculographic variables predict the increase in LVEF after beta-blocker therapy in patients with nonischemic cardiomyopathy (NICM). BACKGROUND: ...
Tanaka H - - 2001
We investigated alpha-adrenoceptor-mediated positive chronotropic action in children using a pharmacological autonomic function test. Under cardiac vagal and sympathetic blockade, chronotropic responses to intravenous infusion of an alpha-agonist, phenylephrine, were determined in 129 patients with suspected autonomic dysfunction. Heart rate changes to phenylephrine infusion (0.4 microg/kg/min) for 5 minutes ranged ...
Hawken E R - - 2001
To date, there have been no reports on the use of propranolol in electroconvulsive therapy (ECT)-induced migraine; we describe a 32-year-old woman who was successfully treated with propranolol for this condition. Over a course of ECT, the patient developed increasingly severe migraine which was refractory to treatment with acetaminophen, codeine, ...
Veglio F - - 2001
Hypertension is a condition where adrenergic responsiveness, sympathetic activity and adrenoceptors are somewhat altered. Many techniques are available to assess human sympathetic nervous system activity. They each present limitations and disadvantages. Characterization and subdivision of the alpha and beta-adrenoceptors, according to their localization and answer to different agonists, was facilitated ...
Hart S M - - 2000
To briefly discuss the pathophysiology of heart failure and the rationale for the use of beta-blockers in the treatment of chronic heart failure. Key morbidity reduction trials are briefly mentioned, and recent mortality reduction trials are reviewed. General recommendations regarding the use of beta-blockers in heart failure are also included ...
Mortara A - - 2000
The purpose of this study was to investigate in a case-controlled study whether carvedilol increased baroreflex sensitivity and heart rate variability (HRV). In chronic heart failure (CHF), beta-adrenergic blockade improves symptoms and ventricular function and may favorably affect prognosis. Although beta-blockade therapy is supposed to decrease myocardial adrenergic activity, data ...
Laviades C - - 2000
We investigated whether a relationship exists between circulating transforming growth factor beta -1 (TGF-beta(1)), collagen type I metabolism, microalbuminuria, and left ventricular hypertrophy in essential hypertension and whether the ability of the angiotensin II type 1 receptor antagonist losartan to correct microalbuminuria and regress left ventricular hypertrophy in hypertensives is ...
Takeda H - - 2000
In the present study, the beta-adrenoceptor subtypes distributed in the detrusor of the ferret were investigated in functional experiments in vitro and in vivo using a variety of beta-adrenoceptor agonists and antagonists. All the beta-adrenoceptor agonists tested relaxed the isolated detrusor strip, the rank order of potency being (+/-)-(R*, R*)-[4-[2-[[2-(3-chlorophenyl)-2-hydroxyethyl]-amino]propyl]phenoxy]- ...
Wang T - - 2000
The cardiovascular actions of python bradykinin (BK) and substance P (SP) have been investigated in the anesthetized ball python, Python regius. Bolus intra-arterial injections of python BK (0.03-3 nmol/kg) produced concentration-dependent increases in arterial blood pressure, heart rate (HR), and cardiac output concomitant with small decreases in systemic resistance and ...
Witte K - - 2000
OBJECTIVES: Patients with chronic heart failure frequently show blunted circadian blood pressure profiles. The mechanisms involved in the loss of physiological day-night variation are still unclear, but a continuously active sympathetic nervous system could play a role. The present study evaluated long-term consequences of rat heart failure on cardiovascular circadian ...
Cameron O G - - 2000
OBJECTIVE: Increases in adrenergic activity are associated with stress, anxiety, and other psychiatric, neurological, and medical disorders. To improve understanding of normal CNS adrenergic function, CBF responses to adrenergic stimulation were determined. METHODS: Using PET, the CBF changes after intravenous yohimbine, an alpha2-adrenoreceptor antagonist that produces adrenergic activation, were compared ...
Witchitz S - - 2000
Treatment with beta blockers results in improvement in functional status, and reduces mortality in patients with heart failure. A number of differences in the results noted could be due to additional properties of the specific beta blockers studied: absence of cardioselectivity, and existence of a vasodilator effect and of an ...
Antic V - - 2000
We have previously reported that weight gain induced by high-fat diet (HFD) leads to an increase in mean arterial pressure (MAP, +14%) and heart rate (HR, +31%) in the adult rabbit. In the present study, we tested the hypothesis that an increased activity of the sympathetic nervous system may contribute ...
Tsao D A - - 2000
Lead exposure is considered to be a risk factor of cardiovascular disease. To investigate the relationship between lead and cardiovascular disease/hypertension in lead exposure, beta-adrenergic system is explored in this study. We address three topics in this study: (a) the relationship between beta-adrenergic receptor and lead level in heart, aorta, ...
Reddy P L - - 2000
Hemoglobin H (HbH) is a tetramer of four beta chains (present in erythrocytes of alpha thalassemia), whereas hemoglobin A is a tetramer of two alpha and two beta chains. Since HbH is known to bind four times more nitric oxide (a vasodilator) at its sulfhydryls compared to HbA, the present ...
Xu B - - 2000
Some studies suggest that beta-adrenoceptor-mediated vasorelaxation is in part mediated through nitric oxide (NO) release. We wished to determine the contribution of the L-arginine / NO system to vasodilatation in response to beta-adrenoceptor stimulation with isoprenaline or cyclic adenosine-3',5'-monophosphate (cyclic AMP) elevation with forskolin and dibutyryl cyclic AMP in vivo, ...
Nagatsu M - - 2000
BACKGROUND: It is clear that beta-blockers are effective for treatment of congestive heart failure, but their mechanism of action remains controversial. Hypothesized mechanisms include normalization of beta-receptor function and myocardial protection from the effects of catecholamines, possibly by the institution of bradycardia. We hypothesized that beta-blockade-induced bradycardia was an important ...
Anthonio R L - - 2000
In the present study, predictors of complicated initiation of beta blockade in patients with idiopathic dilated cardiomyopathy was studied. We found that generally accepted measures of severity of heart failure are not predictable, whereas low systolic blood pressure (< or =120 mm Hg) was the strongest predictor for problematic (up)titration.
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