Search Results
Results 301 - 350 of 1010
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Parlow J L - - 1999
BACKGROUND: Patients with essential hypertension show altered baroreflex control of heart rate, and during the perioperative period they demonstrate increased circulatory instability. Clonidine has been shown to reduce perioperative circulatory instability. This study documents changes in measures of heart rate control after surgery in patients with essential hypertension and determines ...
Mantz J - - 1999
Pharmacological manipulation of the sympathetic tone has led to the synthesis of novel compounds to control stress-induced hemodynamic disorders. The use of alpha(2)-adrenoceptor agonists is particularly interesting in this regard, since these agents decrease sympathetic activity by reducing norepinephrine release from nerve terminals. Dexmedetomidine is a potent, highly selective alpha(2)-adrenoceptor ...
Azevedo E R - - 1999
OBJECTIVES: We studied the effects of clonidine on cardiac sympathetic activity and left ventricular function in patients with congestive heart failure (CHF). BACKGROUND: Sympathetic activation has major prognostic implications in patients with heart failure. Clonidine, an imidazoline and alpha2-receptor agonist, has been shown to cause a reduction in generalized sympathetic ...
Dias V C - - 1999
The objective of this study was to assess the efficacy and tolerability of transdermal clonidine in inner-city African-American and Hispanic-American patients with essential hypertension. A multiclinic open-label, prospective trial for 12 weeks was used. Dose titration was based on office blood pressure (BP) measurements of > 140/90 mm Hg. Clinical ...
D'Amico M - - 1999
Endothelin-1 (ET-1) (10 pmol) microinjected into the superficial layer of superior colliculus induces decreases in blood pressure (control, 108 +/- 5 mmHg, n=6; ET-1, 71 +/- 4 mmHg, n=5). The effects on blood pressure induced by endothelin-1 were significantly (p<0.05) reduced by pre-administration into the superior colliculus of the alpha1-adrenoceptor ...
Savino E A - - 1999
The aim of the investigation was to examine the effects of cooling on the tail artery regarding the scarceness of such studies in spite of the essential thermoregulatory role played by this vessel. Segments of the proximal portion were suspended isometrically in medium containing 1.25 mM Ca. Lowering the temperature ...
Nurminen M L - - 1998
The effects of moxonidine on blood pressure, heart rate and sympathetic tone were studied in conscious spontaneously hypertensive rats. Intravenous moxonidine (80 nmol) transiently increased blood pressure without affecting heart rate or splanchnic nerve activity. Moxonidine (20-80 nmol) given into the fourth cerebral ventricle dose-dependently lowered mean arterial pressure, heart ...
Watanabe Y - - 1998
PURPOSE: To evaluate the effects of clonidine on responses to adrenoceptor agonists and baroreflex sensitivity, we examined arterial blood pressure (AP) responses to phenylephrine and heart rate (HR) responses to isoproterenol and baroreflex sensitivity (HR response to AP changes due to phenylephrine or nitroglycerin). METHODS: We studied 60 anaesthetized patients ...
Medvedev O S - - 1998
Earlier findings have shown that hypotensive effects of centrally acting drugs, such as clonidine, are enhanced in animals after denervation of arterial baroreceptors. The purpose of this study was to investigate the dynamic of changes in arterial pressure, heart rate and hypotensive effects of clonidine, rilmenidine and moxonidine in Wistar ...
Medvedev O S - - 1998
In the present study we investigated the chronopharmacological dependence of dose-dependent hypotensive and cardiochronotropic effects of the imidazoline-like drugs (clonidine, rilmenidine and moxonidine) in stroke-prone spontaneously hypertensive rats (SHR-SP), using radio-telemetric system (Data Sciences, USA). The 24-h blood pressure, heart rate and locomotor activity profiles showed peak values during the ...
Godwin S J - - 1998
In 10 conscious rabbits, the baroreceptor-heart rate (HR) reflex effects of centrally acting antihypertensive agents with high affinity for imidazoline receptors (IRs), moxonidine and rilmenidine, were compared with clonidine which acts predominantly via central alpha2-adrenoceptors. Dose regimens were chosen to give similar hypotension (-17+/-1 mm Hg) and bradycardia (-27+/-2 b/min) ...
Haastrup A T - - 1998
The dyslipidemia in obese hypertensive persons may contribute to their increased vascular alpha-adrenergic receptor reactivity and tone. To further examine this notion, we conducted 2 studies of pressor sensitivity to phenylephrine, an alpha1-adrenergic receptor agonist, in lean normotensive subjects. In the first study (n=6), pressor responses to phenylephrine were obtained ...
Mao L - - 1998
Previous studies from our laboratory demonstrated an antagonistic hemodynamic interaction between ethanol and clonidine in conscious and in urethane-anesthetized rats. The present study tested the hypothesis that ethanol produces its effect by counteracting clonidine-evoked inhibition of norepinephrine (NE) release at its major site of action, the rostral ventrolateral medulla (RVLM). ...
Bryant C E - - 1998
Medetomidine was administered to sheep and horses at a dose rate of 5 microg kg(-1) (i.v.). Heart rate and blood pressure were recorded. Medetomidine induced bradycardia and a biphasic blood pressure response consisting of a transient hypertension followed by hypotension. Administration of prazosin (an alpha1 adrenoceptor antagonist; 100 microg kg(-1), ...
Schuerch L V - - 1998
Human neuropeptide Y (hNPY) potentiates the postjunctional vasoconstrictor effects of alpha1-adrenoceptor agonists in animals and in human hand veins in vivo. We therefore hypothesized that such an interaction might also occur in the human arterial bed. With the present single-blind cross-over study in 12 healthy volunteers, the effect of subpressor ...
Benhamou D - - 1998
Seventy-eight pregnant women at term, scheduled for elective cesarean section, were enrolled in this multicenter trial to compare the analgesic efficacy and side effect profile of a spinal block with hyperbaric bupivacaine alone (Group B) or combined with 75 microg of clonidine (Group BC) or with clonidine 75 microg and ...
Winslow R M - - 1998
We have compared polyethylene glycol-modified bovine hemoglobin (PEG-Hb; high O2 affinity, high viscosity, high oncotic pressure) and human hemoglobin cross-linked between the alpha-chains (alpha alpha-Hb; low O2 affinity, low viscosity, low oncotic pressure) with a non-O2-carrying plasma expander (pentastarch, high viscosity and oncotic pressure) after a 50% (by volume) exchange ...
Jost W H - - 1998
Orthostatic hypotension is common in Parkinsonian patients. It is probably caused by reduced noradrenaline (NA) release. This effect is further enhanced by therapeutic use of ergot alkaloid dopamine agonists. In this trial we studied the impact of the non-ergot dopamine agonist ropinirole on blood pressure and noradrenaline release in 12 ...
Tanaka J - - 1998
To verify whether noradrenergic inputs to the subfornical organ (SFO) are involved in the control system of arterial pressure, we investigated the effects of blood pressure changes on noradrealine (NA) release in the SFO and its surrounding sites using microdialysis techniques in rats. Hemorrhage (5 or 10 ml/kg) significantly increased ...
Tagariello V - - 1998
BACKGROUND AND OBJECTIVES: Spinal mepivacaine has been reported as a reliable anesthetic for ambulatory anesthesia. Its pharmacologic properties are midway between those of bupivacaine and lidocaine, and it can be used in intermediate duration ambulatory surgical procedures. METHODS: A patient taking clonidine transdermal patches (TTS) to control high blood pressure ...
Taittonen M T - - 1998
The use of ketamine as a sole anesthetic induces marked central sympathetic stimulation, causing increased heart rate, blood pressure (BP), and oxygen consumption (VO2). Both alpha 2-agonists and benzodiazepines have been used to attenuate these potentially harmful ketamine-induced responses. This double-blind, randomized, placebo-controlled study was designed to compare the perioperative ...
Kimura T - - 1998
BACKGROUND: Clonidine reduces heart rate (HR) responses to atropine, whereas neostigmine causes bradycardia. This study was designed to determine whether clonidine premedication would reduce tachycardia after neostigmine-atropine administration. METHODS: Fifty adult patients without cardiovascular disorders who were scheduled for elective surgeries were randomly assigned to receive approximately 5 microg/kg (oral ...
Furuhata K - - 1998
T-3762, a newly developed fluoroquinolone antimicrobial agent, ciprofloxacin (CPFX) and ofloxacin (OFLX) were administered intravenously to anesthetized dogs by intravenous infusion, and blood pressure, heart rate and plasma histamine concentrations were monitored. T-3762 decreased blood pressure by 12.0%, without alterations in heart rate and plasma histamine concentration, only when infused ...
Mestivier D - - 1998
In spontaneously hypertensive rats (SHR), chronic infusion of clonidine failed to decrease blood pressure and blood pressure variability. We used nonlinear methods to get a deeper insight on the effects of clonidine on blood pressure dynamics. For 24 h and 4 wk, clonidine (0.1 mg . kg-1 . day-1 sc) ...
Costello T G TG St. Vincent's Hospital, Fitzroy, Melbourne, - - 1998
The aim of this study was to compare hemodynamic responses to intubation and pin head-holder application in two groups of neurosurgical patients given oral clonidine (3 microg/kg) or oral temazepam (10-20 mg) 90 min before the induction of anesthesia. Fifty patients undergoing elective craniotomy were randomized to either group. Anesthesia ...
Conkin J - - 1998
The intensity of a pain-only decompression sickness (DCS) symptom with respect to time at altitude increases, peaks, and then declines in some cases. A similar pattern is also seen in a graph of the probability density function [f(t)] for DCS. The f(t) is the proportion of DCS per unit time ...
Beninger F G - - 1998
Blood pressure control is an important part of any surgical procedure and is especially important during rhytidectomy to reduce the risk of bleeding, improve visualization, and reduce the risk of postoperative fluid accumulations. For patients given general anesthetic, b blood pressure control is regulated by intravenous fluids, inhalational gas concentrations, ...
De Kock M - - 1998
In this prospective, nonblind study, we report the use of clonidine during orthotopic liver transplantation (OLT). Twenty adult patients in a stable medical condition were studied. General anesthesia consisted of isoflurane in air/oxygen and sufentanil. Patients in the clonidine group received a slow i.v. infusion (15 min) of 4 microg/kg ...
Chan T Y TY Division of Clinical Pharmacology, Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong - - 1998
The ranges of sodium and potassium intake and their relationship to blood pressure were studied in 126 healthy Chinese subjects (42 men, 84 women) aged between 20 and 65 years living in Hong Kong. An average of three blood pressure measurements and one to three 24-hour urinary sodium and potassium ...
Czapla M A - - 1998
The endogenous opioid peptides, endomorphin 1 and 2, are newly isolated, potent, and selective mu-opioid receptor agonists. In the present study, responses to endomorphin 1 and 2 were investigated in the systemic vascular bed of the rat. Endomorphin 1 and 2 induced dose-related decreases in systemic arterial pressure when injected ...
Khayyal M T - - 1998
Hypercholesterolemia is known to affect the responsiveness of various blood vessels to endogenous and to exogenous vasoactive agents. Of particular interest is the increased responsiveness to vasoconstrictors, e.g., 5-hydroxy tryptamine and noradrenaline, and the decreased reactivity towards vasodilators, e.g., acetylcholine. This, together with the development of arteriosclerosis, could play an ...
Lim D Y - - 1998
This study was designed to investigate the effect of endothelin-1 (ET-1) on clonidine-induced cardiovascular effects in urethane-anesthetized rabbits and to clarify the mechanism of its action. Clonidine (5, 10, and 20 micrograms/kg) given into a femoral vein (i.v.) produced a marked dose-dependent fall in arterial blood pressure and heart rate, ...
Champion H C - - 1998
The endogenous peptides endomorphin 1 and 2 are newly isolated, potent, selective mu-opioid receptor agonists. In the present study, responses to the endomorphin peptides were investigated in the systemic vascular bed of the cat. Endomorphin 1 and 2 induced dose-related biphasic changes in systemic arterial pressure when injected in doses ...
Yamaguchi S - - 1997
Axial tooth movements and arterial blood pressure were measured following the intravenous injection of 0, 0.01, 0.1, 1, or 10 micrograms/kg of adrenaline, noradrenaline or isoprenaline. Adrenaline caused a dose-dependent, rapid, extrusive tooth movement with a nearly simultaneous increase in blood pressure, followed by a marked intrusive tooth movement and ...
Bharucha A E - - 1997
Our aims were to assess the role of adrenergic modulation in the hyperventilation-induced increase in colonic tone. Of 40 healthy volunteers, 12 received placebo (saline) and the remaining 28 received either clonidine, yohimbine, phenylephrine, or ritodrine. Time-frequency mapping of heart rate based on Wigner distribution assessed variations in parasympathetic and ...
Del Bo A - - 1997
BACKGROUND: Changes in plasma osmolality and arterial pressure can affect the secretion of vasopressin (AVP). OBJECTIVE: To investigate the effect of a drug-induced lowering of the arterial pressure on the plasma concentration of AVP and on its osmoregulation in moderately severe uncomplicated hypertensives. DESIGN AND METHODS: A group of 33 ...
Iriuchijima J - - 1997
The original aim of this study was to observe whether the depressor drug clonidine inhibited the abnormal hindquarter tone in spontaneously hypertensive rats (SHR). In conscious SHR and normotensive control rats (NCR), hindquarter (terminal aortic) blood flow was observed with an implanted electromagnetic flow probe and mean arterial pressure with ...
Gregorakos L - - 1997
OBJECTIVE: To evaluate the effectiveness of clonidine in the management of unstable blood pressure in severe tetanus. DESIGN: Patients with severe tetanus and blood pressure instability were treated with clonidine and the results were compared with those of other patients with severe tetanus who were not treated with clonidine. SETTING: ...
El-Mas M M - - 1997
Our previous studies have shown that ethanol selectively counteracts centrally mediated hypotensive responses. This study investigated the role of cardiac output and peripheral resistance in the antagonistic interaction between ethanol and antihypertensive drugs. Changes in blood pressure, heart rate, cardiac index, stroke volume, and peripheral resistance elicited by clonidine and ...
You-hua Z - - 1997
In this double-blind, placebo-controlled crossover study, we examined the effect of transdermal clonidine (given for 5 days) on autonomic control in 14 patients with mild to moderate congestive heart failure by heart rate variability analysis. Compared with placebo, clonidine increased the 24-h mean R-R interval from 718+/-110 to 811+/-117 ms ...
Taittonen M T - - 1997
Premedication has been shown to affect both oxygen consumption and metabolic rate. We have compared the perioperative metabolic and haemodynamic effects of two alpha 2-agonists, clonidine and the more selective dexmedetomidine, in 30 ASA I patients undergoing plastic surgical procedures under general anaesthesia. Patients were premedicated with clonidine 4 micrograms ...
Schmidt M E - - 1997
Seven male and five female volunteers underwent double-blind infusions of the alpha 2-adrenoceptor antagonist idazoxan (100 and 200 micrograms/mg) and placebo in random order. Blood pressure, plasma norepinephrine, growth hormone and subjective responses were measured. The higher dose of idazoxan produced increases in blood pressure, norepinephrine and growth hormone and ...
Bealer S L - - 1997
The roles of alpha-adrenoceptors in the anteroventral third ventricle (AV3V) and diagonal band of Broca (DBB) in cardiovascular responses to peripheral hypertonicity were investigated in conscious rats. Normal artificial cerebrospinal fluid (aCSF) or aCSF containing phentolamine (alpha1- and alpha2-antagonist), yohimbine (alpha2-antagonist), or prazosin (alpha1-antagonist) was perfused through microdialysis probes in ...
De Negri P - - 1997
BACKGROUND: Clonidine, an alpha 2 agonist, is known to prolong the action of local anesthetics, and to provide a satisfactory analgesia; hypotension and bradycardia have been observed after its intrathecal administration. The aim of our study was to determine whether intrathecal administration of clonidine can reduce the dose of local ...
Rubio G - - 1997
Blood pressure and heart rate were monitored in heroin addicts detoxified with guanfacine in an outpatient program. Retrospective analysis of the cardiovascular parameters from the addicts who failed this detoxification during the first 5 days of treatment (they consumed heroin within this period) showed that these patients experienced less hypotension ...
Jonsson M - - 1997
We have studied the role of neutrophils and the effects of the chemotactic factor FMLP, using normal, neutropenic (after cyclophosphamide treatment) and C5a desArg-treated unanesthetized rabbits. The intravenous administration of FMLP in normal animals induces transient and dose-dependent hypotension, neutropenia and thrombocytopenia, with a maximal response in 3 minutes. When ...
Taittonen M - - 1997
In this double-blind placebo controlled study the preoperative cardiovascular and metabolic effects of intramuscular (i.m.) clonidine and midazolam are assessed. Forty-five ASA Grade I patients (n = 15 per group) undergoing plastic surgical procedures were randomly allocated to receive either placebo, clonidine 4 micrograms kg-1 or midazolam 70 micrograms kg-1. ...
Bergendahl H T - - 1997
The beneficial perioperative effects of the alpha-2 agonist clonidine have recently been verified in paediatric patients, and the pharmacokinetics have been found to be similar to what has been reported in adults. In a previous study we found that 2.5 micrograms/kg of clonidine causes a significant reduction in blood pressure. ...
ter Minassian A - - 1997
alpha 2-Adrenergic agonists induce cerebral vasoconstriction, reduce intracranial pressure (ICP) in experimental animals and may be useful in the hemodynamic management of head-injured patients. We studied the effects of the alpha 2 agonist clonidine on the cerebral circulation in 12 head-injured patients (Glasgow Coma Scale score < 8). Middle cerebral ...
Prichard B N - - 1997
Imidazoline I1-receptor agonism represents a new mode of antihypertensive action to inhibit peripheral alpha-adrenergic tone by a central mechanism. Adrenaline, noradrenaline and renin levels are reduced, a finding consistent with central inhibition of sympathetic tone. Acute haemodynamic studies indicate that moxonidine results in an acute decrease in blood pressure due ...
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