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Porchet H C - - 1992
Although clonidine analgesia appears to be mediated by the same central alpha 2-adrenoceptors that mediate its hypotensive effect, it is short-lasting when compared to the fall in blood pressure. This has been investigated by combined pharmacokinetic-pharmacodynamic analysis in 10 healthy volunteers who received (double-blind and crossover) clonidine 200 micrograms orally ...
Hamilton C A - - 1992
Rabbits were treated with guanabenz, clonidine and rilmenidine for 6 days via osmotic minipumps. Blood pressure, heart rate and responses to intracisternal clonidine were measured after 1 and 6 days treatment. Radioligand binding to forebrain and hindbrain membranes after 6 days treatment was examined using [3H]yohimbine to measure the number ...
Borbe H O - - 1991
Naftopidil, a novel antihypertensive compound, possesses 5-HT1A agonistic properties in addition to being an alpha 1-adrenoceptor antagonist. The IC50 values for alpha 1-adrenoceptors (235 nmol/l) and for 5-HT1A receptors (108 nmol/l) lie in the same concentration range. The reduction in blood pressure of anesthetized cats by 8-OH-DPAT and urapidil was ...
Schafers R F - - 1991
1. Abanoquil (UK 52,046) is a novel, quinoline-derivative, alpha 1-adrenoceptor antagonist which, on the basis of animal studies, possesses antiarrhythmic activity at doses which have little or no effect on blood pressure. 2. In two placebo-controlled, double-blind, crossover studies the alpha 1-adrenoceptor antagonist activity (phenylephrine pressor responses) and the effects ...
Schafers R F - - 1991
1. This study further examines the quinoline-derivative abanoquil with particular respect to the duration of its alpha 1-adrenoceptor antagonist activity and its concentration-effect relationship following a single intravenous bolus dose of 0.5 micrograms kg-1 in young, normotensive males. 2. alpha 1-adrenoceptor antagonism (as assessed by phenylephrine pressor responses) was detectable ...
Yorikane R - - 1991
Antiarrhythmic and cardiovascular profiles of a fused indole compound, (3aR,12R,12aR,12bS)-12-amino-2,3,3a,4,11,12,12a,12b -octahydro- 10-hydroxyisoquino [2,1,8-lma]carbazol-5(1H)-one hydrochloride 1.5 hydrate (RS-2135, CAS 133775-36-7), were investigated in anesthetized dogs. Class I antiarrhythmic agents such as disopyramide, lidocaine, mexiletine and flecainide were used as reference compounds. RS-2135 exerted more potent antiarrhythmic activity than reference compounds against ...
Dabiré H - - 1991
The systemic and regional hemodynamic effects of the selective 5-HT1A receptor agonist flesinoxan (3-300 micrograms/kg, i.v., in cumulative doses) were investigated in normotensive anesthetized and pithed rats using a pulsed Doppler system and were compared to those of the alpha 2-adrenoceptor agonist clonidine. In anesthetized rats, flesinoxan and clonidine induced ...
Sporton S C - - 1991
1. The effects of microinjections (100 nl) into the dorsal motor vagal nucleus of the 5-HT1A receptor agonists 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) and flesinoxan, the 5-HT2 receptor agonist (+-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane hydrochloride (DOI), the 5-HT3 receptor agonist phenylbiguanide (PBG), the alpha 2-adrenoceptor agonist clonidine and the excitatory amino acid glutamate on heart rate, blood ...
Kooner J S - - 1991
The contribution of neurogenic mechanisms in maintaining hypertension was investigated in 13 patients with unilateral renal artery stenosis (twelve with normal, one with grossly elevated plasma renin levels) by determining the haemodynamic and hormonal responses to the centrally acting sympatholytic agent, clonidine. The same patients were studied after captopril to ...
Knoll-Köhler E - - 1991
Since knowledge of the bioavailability of adrenaline from the intraoral submucosal depot is a prerequisite for its safe use in dentistry, the time-dependent effects of adrenaline on the plasma adrenaline level and cardiohaemodynamic parameters were studied with invasive methods in adrenalectomized, anaesthetized rats after injection of adrenaline (4.0 micrograms/kg body ...
Ooi R - - 1991
The effects of clonidine, an alpha 2 adrenergic agonist, on ventilation were studied in a group of adult volunteers. The ventilatory variables measured were minute ventilation, respiratory rate, end-tidal carbon dioxide tension and the response to carbon dioxide challenge. We found no differences in minute ventilation, respiratory rate and end-tidal ...
Kooner J S - - 1991
BACKGROUND: Clonidine, a partial presynaptic and postsynaptic alpha-adrenoceptor agonist, has been shown to lower blood pressure in normal subjects but not in tetraplegics; however, the mechanisms of this action have not been elucidated. METHODS AND RESULTS: The hemodynamic and hormonal basis of the hypotensive action of clonidine was investigated in ...
Lueg M C - - 1991
An open-label study was conducted to evaluate the clinical safety and efficacy of transdermal clonidine as an adjunct to sustained-release (SR) diltiazem (90 mg twice daily) in mild-to-moderate hypertension. Ninety patients with a mean baseline sitting blood pressure of 154/102 mmHg were given 90 mg of diltiazem SR twice daily ...
Overton J M - - 1991
Corticotropin-releasing factor (CRF) modifies cardiovascular function and hemodynamic status after administration into the central nervous system and into the peripheral circulation. The mechanisms by which CRF alters arterial pressure and heart rate have been examined in detail whereas little information exists regarding the processes mediating CRF-induced changes in regional blood ...
Du Z Y - - 1991
1. The effect of tolerance to glyceryl trinitrate (GTN) on vasodilator and vasoconstrictor responses was examined in conscious rabbits and isolated rabbit aortic rings. 2. In conscious rabbits, depressor responses to 5 min infusions of GTN (10-40 micrograms/kg per min intravenously (i.v.)), sodium nitroprusside (SNP, 5-20 micrograms/kg per min i.v.) ...
Penon C - - 1991
The authors studied the effects of epidural clonidine (300 micrograms) on circulation and ventilatory control in seven healthy unpremedicated subjects. After clonidine injection, arterial blood pressure decreased significantly in all subjects (range, 13%-25% for systolic blood pressure and 13%-32% for diastolic blood pressure). Heart rate decreased significantly by 10%-16% between ...
Mandal A K - - 1991
Our study had three purposes: 1) to determine whether 5-methyl-urapidil, topically applied to the ventrolateral medulla, produces hypotension by activating serotonin-1A (5-HT1A) receptors, 2) to determine whether 5-methyl-urapidil given i.v. produces hypotension in part by activating 5-HT1A receptors in the ventrolateral medulla, and 3) to determine the specific site within ...
Laurito C E - - 1991
STUDY OBJECTIVE: To determine the effects of oral clonidine premedication on sedative, anxiolytic, and hemodynamic responses during the immediate preoperative period, laryngoscopy/intubation, and postanesthetic recovery. DESIGN: Randomized double-blind assignment to one of four treatment groups (clonidine 0.1 mg, clonidine 0.2 mg, triazolam 0.25 mg, or placebo); n = 10 per ...
Martí-Cabrera M - - 1991
The intravenous infusion of mannitol (1.37 mosm kg-1 min-1 during 4 min) to anesthetized, open-chest, intact dogs produced a hemodynamic response characterized by a positive inotropic effect and a decrease in total peripheral resistance. This response is attributable to a direct effect of hypertonicity (plasma osmolality raised from 309 +/- ...
Eisenach J C - - 1991
Intrathecally administered alpha 2-adrenergic agonists produce analgesia in humans but may also produce hypotension and bradycardia. To further characterize hemodynamic depression produced by intrathecally administered alpha 2-adrenergic agonists, clonidine (100-1,500 micrograms) was injected into the cervical, thoracic, or lumbar intrathecal space of conscious sheep. Only thoracic intrathecal clonidine injection (100 ...
Barnes J C - - 1991
The in vivo central effects of a range of full and partial muscarinic receptor agonists have been investigated on hippocampal theta rhythm and blood pressure. In the isoflurane-anaesthetised rat, pretreated with N-methylscopolamine, i.v. administration of arecoline, oxotremorine, arecaidine propargyl ester, aceclidine and pilocarpine produced dose-dependent increases in the frequency of ...
Wilson T W - - 1991
Between 1975 and 1988, demographic data, weight and height measurements, and blood pressure readings were obtained for 77 890 residents of Saskatchewan (about 7.6% of the population). High readings were present in 7.8% of those surveyed, but prevalence fell over the lifetime of the survey. Subjects whose drug therapy was ...
Tomlinson B - - 1991
Intravenous urapidil, 40 mg bolus followed by an infusion of 18 mg.h-1 for 2 h was administered to 6 female non-patient volunteers. Randomised cumulative dose response curves to angiotensin, phenylephrine and isoprenaline were performed before and commencing 30 min after the start of the infusion of urapidil. Urapidil significantly reduced ...
Bernard J M - - 1991
The effects of clonidine, a central alpha 2-adrenoreceptor agonist, on haemodynamic and catecholamine changes were assessed during emergence from anaesthesia, a period which is associated with increased sympathetic nervous discharge, hypertension and tachycardia. According to a double-blind randomized design, 32 patients received either clonidine, preoperatively given by oral route (3.5 ...
Glue P - - 1991
The effects of alpha 2-adrenoceptor agonists and antagonists on saccadic eye movements were studied in normal volunteers using the agonist clonidine and the antagonist idazoxan. Changes in blood pressure, heart rate, and several psychological self-ratings were also recorded. Clonidine produced marked slowing of peak saccade velocity, acceleration and deceleration, with ...
Quintin L - - 1991
After completion of abdominal aortic graft, 29 patients received an i.v. infusion of placebo (n = 16) or clonidine 7 micrograms kg-1 (n = 13) over 120 min in a double-blind study. Cardiovascular variables were measured and plasma samples obtained up to 5 h after arrival in the recovery room, ...
Shue C H - - 1991
The response of canine trachea to exogenous dopamine was studied in vivo. Pentobarbital-anesthetized dogs were treated with dopamine through i.v. injection and i.v. infusion. The dopamine-induced constriction of the trachea was evaluated from changes in the intraluminal pressure of a semi-isolated section. The respiratory flow was monitored with a pneumotachograph. ...
Spiers J P - - 1991
The effects of acute and chronic oral administration of UK-52,046 (25 micrograms kg-1) on baroreflex function and its duration of action, were studied in conscious dogs. It was found that UK-52,046 had no effect on blood pressure and heart rate following acute and chronic administration. UK-52,046 shifted the phenylephrine dose ...
Smits J F - - 1991
Rilmenidine is an oxazoline analogue that has antihypertensive properties that resemble those of clonidine. Since rilmenidine has recently been described to have a relatively greater affinity for imidazoline receptors than clonidine, it was of interest to study whether this has functional consequences with regard to the regional hemodynamic responses. We ...
Bailey P L - - 1991
Because only limited and controversial data exist concerning the respiratory effects of clonidine in humans, the authors evaluated the respiratory effects of clonidine alone and in combination with morphine, in 12 healthy adult males. Subjects received clonidine (0.3-0.4 mg orally), morphine (0.21 mg/kg intramuscularly), or the same doses of the ...
Vainio O - - 1990
The effects of atipamezole, an alpha 2-antagonist, on six medetomidine-sedated laboratory beagles were studied in a randomised complete block design. The dogs were sedated with medetomidine (20, 40 or 80 micrograms/kg intramuscularly) and five- and 10-fold larger doses of atipamezole were administered intramuscularly 30 minutes later. Atipamezole significantly increased the ...
Toivonen J - - 1990
The effect of clonidine on the dose requirements of labetalol and isoflurane for hypotension was studied in 20 adult patients undergoing middle-ear surgery. Group I (10 patients) received as premedication only pethidine 1 mg.kg-1 i.m., and Group II (10 patients) clonidine 4-5 micrograms.kg-1 p.o. in addition to pethidine. Fentanyl was ...
Mann J J - - 1990
The role of activation of adrenergic neurons by electroconvulsive therapy (ECT) in its antidepressant action was studied by examining acute sympathetic nervous system (SNS) responses to ECT during a course of treatment in patients with melancholia. ECT had an acute dose-dependent effect on plasma norepinephrine (NE) level and blood pressure. ...
Williams C A - - 1990
STUDY OBJECTIVE: The aim was to determine whether areas in the periaqueductal grey matter, medial dorsal raphe, or ventrolateral medulla might be involved with the integration of blood pressure and heart rate during isometric exercise. DESIGN: Cats were anaesthetised with alpha chloralose (75 mg.kg-1) and catheters inserted into the right ...
Mas M S - - 1990
Vasoactive intestinal polypeptide (VIP) is a neuropeptide with potent circulatory effects in the adult animal and human. Little is known about its effects or mechanism of action in the immature animal. These series of experiments evaluated the effects and possible mechanism of action of VIP on the developing canine cardiovascular ...
Estan L - - 1990
1. The aim of the present study was to investigate the influence of catecholamine levels on the regulation of alpha 2-adrenoceptor sensitivity in dogs. 2. Blood pressure and heart rate values at rest, plasma catecholamine levels, platelet and adipocyte alpha 2-adrenoceptors as well as the alpha 2-mediated cardiovascular responses to ...
Yamato S - - 1990
The purpose of the present investigation was to examine the role of alpha adrenoceptors in the internal anal sphincter (IAS). Studies wer performed on alpha-chloralose anesthetized opossums. Resting pressure in the IAS (IASP) was recorded using low compliant continuously perfused catheters. The effects of the alpha-1 adrenoceptor agonist phenylephrine and ...
Greene C S - - 1990
A major risk associated with the acute treatment of severe hypertension is a reduction in cerebral blood flow (CBF) with ischemic injury to the central nervous system. The authors studied CBF before and after the acute treatment of severe hypertension (diastolic blood pressure greater than 115 mm Hg) with clonidine ...
Kallio A - - 1990
Single intravenous (i.v.) doses of 4(5)-[1-(2,3-dimethylphenyl)ethyl]imidazole, medetomidine (MED), (25, 50, and 100 micrograms) and clonidine (CLO 200 micrograms) were administered to five healthy male volunteers in a randomized, double-blind, placebo-controlled, multiple cross-over study. The hemodynamic effects of the drugs were determined by a two-dimension Doppler-echocardiographic method. Blood pressure (BP) and ...
Chiang J - - 1990
The pharmacologic response to drugs is generally assumed to be related to the unbound concentration of the active species. This study, however, reports that the alpha-1 adrenergic blocking activity of prazosin is lower in the presence than in the absence of the plasma protein alpha-1-acid glycoprotein (AAG), at the same ...
Rioux F - - 1990
Intraperitoneal (IP) injections of either 1, 3 or 9 ml of neurotensin-containing solutions (NTCS) with 5.4, 54, 540 or 5400 nM of neurotensin (NT) were found to cause concentration-dependent, but volume-independent, increases of blood pressure (BP) and heart rate (HR) in anesthetized, close-abdomen guinea pigs. The duration of both effects ...
Singh P P - - 1990
The effect of various hypotensive agents were simultaneously tested on locomotor activity and blood pressure of unanaesthetised (conscious) rats. The agents viz clonidine, prazosin, furosemide and hexamethonium were found to reduce significantly the locomotor activity as well as blood pressure, 30 min post administration. Phenoxybenzamine and alpha-methyldopa produced similar type ...
Butterworth J F JF - - 1990
Ca and phenylephrine, both of which increase mean arterial pressure (MAP), are often administered concurrently during resuscitation of critically ill patients. To determine whether the response to phenylephrine is potentiated by Ca administration, we studied eight adult patients 24 h after aortocoronary bypass surgery. Each patient received three doses of ...
Polikar R - - 1990
Nine hypothyroid patients had blood pressure and pulse rate responses to the alpha-adrenergic agonist phenylephrine measured before [T4 index, 45.045 +/- 9.009 nmol/L (mean +/- SEM); TSH, 57.1 +/- 23.6 mU/L] and after 4 +/- 0.5 months of thyroid replacement therapy (T4 index, 141.570 +/- 29.601 nmol/L; TSH, 2.6 +/- ...
Piascik M T - - 1990
The effect of chlorethylclonidine on alpha 1-adrenoceptor subtypes and arterial blood pressure has been evaluated. Chlorethylclonidine significantly reduced the alpha 1-adrenoceptor population. Chlorethylclonidine treatment had no significant effect on resting systemic arterial blood pressure or heart rate and shifted the phenylephrine pressor dose-response curve only 2.4-fold to the right. These ...
Lee M A - - 1990
Ten patients with obsessive-compulsive disorder (OCD) and 13 normal control subjects received intravenous infusions of 2 X 10(-6) g/kg of clonidine and normal saline on separate days. Responses to the drug relating to plasma growth hormone (GH), 3-methoxy-4-hydroxyphenylglycol (MHPG), heart rate, blood pressure, and several symptoms were determined. Additionally, platelet ...
Aho M - - 1990
Ninety women undergoing gynecologic laparoscopy were randomly given clonidine 3 or 4.5 micrograms/kg or saline intramuscularly 45-60 min prior to induction of anesthesia. Anesthesia was induced with thiopental 3.5 mg/kg and maintained with 0.3% end-tidal isoflurane in nitrous oxide and oxygen. The laparoscopy did not begin sooner than 20 min ...
Newman C M - - 1990
1. A new model of tolerance to the hypotensive effect of organic nitrates has been developed in the rat. 2. The fall in mean arterial pressure (MAP) in response to bolus doses of sodium nitroprusside (NP) (4 micrograms kg-1) and glyceryl trinitrate (GTN) (10 micrograms kg-1) was recorded both before ...
Ernsberger P - - 1990
The rostral ventrolateral medulla is the primary site of action for clonidine, a centrally acting antihypertensive. In the rostral ventrolateral medulla, clonidine binds not only to alpha-2 adrenergic receptors but also to specific imidazole sites. In order to determine whether a putative imidazole receptor mediates the hypotensive action of clonidine, ...
Nolan A M - - 1990
The alpha 2 agonist xylazine produced a dose-dependent decrease in mean arterial blood pressure in conscious rabbits when injected intrathecally (i.t.) through a cannula previously implanted under general anaesthesia. Intrathecal administration of 200 and 400 micrograms of xylazine produced a significant reduction in arterial blood pressure from control values (maximum ...
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