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Results 401 - 450 of 1019
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Wyse D G - - 1995
This cross-sectional study examined responses of the isolated cystic artery to 3 alpha-adrenoceptor agonists and the effects of 2 antagonists in relation to subjects' blood pressures. Potency of the 3 amines studied was: alpha-methylnorepinephrine > norepinephrine > phenylephrine. Responses to clonidine were trivial (< 5% of maximum) and remained < ...
Richter R M - - 1995
Three assays have been used to show that the neuropeptides human corticotropin-releasing factor (hCRF) and the ovine analogue oCRF produced substantial dose-dependent cardiovascular responses. The assays included intracerebroventricular (ICV) and intravenous (IV) administration in conscious rats, and also in vitro experiments with resistance arteries. Central administration of the peptides (0.1-10 ...
Fantaskey A - - 1995
Venlafaxine hydrochloride is a novel bicyclic antidepressant which inhibits the reuptake of serotonin, norepinephrine and, to a lesser extent, dopamine. A 41-year-old female ingested 4.5 g venlafaxine, 500 mg diphenhydramine, 50 mg thiothixene and subsequently experienced severe central nervous system depression requiring intubation. She also developed elevated systolic and diastolic ...
Sun X - - 1994
The modulatory effects of alpha-trinositol (D-myo-inositol-1.2.6- trisphosphate; PP 56) on the systemic arterial blood pressor responses induced by neuropeptide Y, preganglionic nerve stimulation, phenylephrine and vasopressin were studied in pithed rats. Intravenous administration (within 2 min.) of alpha-trinositol reduced the neuropeptide Y-induced increase in mean arterial pressure within a defined ...
Bernard J M - - 1994
Agonist interactions in antinociceptive effects between clonidine and opioids can be used to reduce opioid requirements in surgical patients. However, clonidine can cause marked sedation and associated respiratory dysfunction. Thus, the benefit of using clonidine to reduce opioid use on respiration is questionable. This double-blind randomized study compared the analgesic ...
Abdel-Rahman A A - - 1994
This study tested the hypothesis that concurrent ethanol administration attenuates the hypotensive effect of clonidine. Four groups of spontaneously hypertensive rats matched for baseline systolic pressure and body weight were randomly assigned the following treatments: (1) water (control), (2) ethanol, (3) clonidine, and (4) ethanol plus clonidine for 13 weeks. ...
Cheskin L J - - 1994
We compared the short-term efficacy of a high-dose, 3 day regimen of buprenorphine to a standard 5-day course of clonidine in attenuating the signs and symptoms of the acute opioid abstinence syndrome during rapid detoxification from heroin in 25 men and women admitted to a closed inpatient research ward for ...
Wocial B - - 1994
Neuropeptide Y (NPY) is a vasoconstrictor sympathetic cotransmitter and a modulator of adrenergic function whose role in hypertension is yet unknown. We studied the co-release of NPY and noradrenaline (NA) in patients with essential hypertension (13 females, 11 males, age 42 +/- 13 years) by measuring plasma levels of NPY-immunoreactivity ...
Fischetti F - - 1994
Clonidine, an imidazoline derivative, is a widely used antihypertensive agent which acts by stimulating the alpha 2-adrenergic receptors at the central nervous system. Clonidine also seems to exert beneficial effects on baroreceptor reflex sensitivity which is usually altered by arterial systemic hypertension and arteriosclerosis. Aim of the study was to ...
Di Francesco G F - - 1994
The cardiovascular effects of the 5-HT1A receptor agonists MDL 73,975 (8-[2-(2,3-dihydro-8-methoxy-1,4-benzodoxin-2-yl)methylaminol++ +]-ethyl]-8- azaspiro[4,5]decane-7,9-dione hydrochloride) and flesinoxan (10-300 micrograms/kg subcutaneously, s.c.), the 5-HT1A receptor antagonist NAN 190 (2-[4-[4-(2-methoxyphenyl)-1-piperazinyl]butyl]-1H-isoindole-1,3(2H)- dione,1,2-ethanedioate), and the alpha 1-adrenoceptor antagonist prazosin have been investigated in conscious normotensive and renal hypertensive dogs. In normotensive dogs the increases in ...
Imai N - - 1994
We have shown previously that right heart failure (RHF) in dogs is associated with activated endogenous opiate systems, and that administration of the opioid receptor antagonist, naloxone, increases arterial pressure, cardiac contractile function and organ blood flows. To study whether the cardiovascular effects of naloxone are mediated via the mu- ...
Kenny B A - - 1994
OBJECTIVES: In the current study we have profiled a range of compounds at alpha 1 adrenoceptor subtypes in vitro and have assessed their effects in vivo using the anesthetized dog in an attempt to elucidate the predominant alpha 1 adrenoceptor subtype mediating contractile responses of the canine prostate. METHODS: The ...
Mercadante S - - 1994
In obstetric patients treated with epidural analgesia during labor and delivery, shivering is quite frequent due to stress, vasodilatation, infusion of fluids, low ambient temperature, and the direct effect of solution injected into the epidural space. Sixty obstetric patients who developed shivering after receiving epidural analgesia for delivery were randomly ...
Lepage J Y - - 1994
We have studied the effects of urapidil 0.4 mg kg-1 i.v. and clonidine 2.5 micrograms kg-1 i.v. on left ventricular volume and function in 20 patients with chronic coronary artery disease and essential hypertension. Patients were studied using 99mtechnetium radionuclide angiography with first-pass and ECG-gated equilibrium blood-pool techniques and non-invasive ...
Goźlińska B - - 1994
The effect of 2-oxoglutarate aminotransferase inhibitor, aminooxyacetic acid (AOAA) on hypotension induced by clonidine in spontaneously hypertensive rats (SHR) was examined. AOAA given 15 min before clonidine significantly intensified clonidine--induced reduction of blood pressure. This effect reached its maximum within 120 min after AOAA administration, when AOAA itself had no ...
Zoukos Y - - 1994
We have studied beta-adrenoceptor number and affinity on peripheral blood mononuclear cells (PBMCs) in normotensives (NT) and hypertensives (HT), before and after intravenous administration of clonidine, an alpha 2-adrenoceptor agonist which lowers blood pressure predominantly by reducing central nervous system sympathetic outflow. After clonidine, there was a decrease in blood ...
Oloyede A - - 1994
We show that in the early stages of loading of the cartilage matrix extensive water exudation and related physicochemical and structural changes give rise to a distinctly consolidatable system. By enzymatically modifying the pre-existing osmotic condition of the normal matrix and measuring its hydrostatic excess pore pressure, we have studied ...
Prichard B N - - 1994
Moxonidine is an imidazoline receptor modulator, specific for the I1-imidazoline receptor. The stimulation of imidazoline receptors represents a new mode of antihypertensive action to inhibit peripheral alpha-adrenergic tone by a central mechanism. Acute hemodynamic studies reveal moxonidine produces an acute fall of blood pressure and systemic vascular resistance. Heart rate, ...
Blanc J - - 1994
1. Power spectral analysis of the frequency of wave-forms of blood pressure and heart rate was used to characterize short-term fluctuations of these parameters in three strains of conscious Lyon rat, normotensive (LL and LN) and hypertensive LH. 2. A mild stress produced by means of a jet of air ...
Del Rio G - - 1994
OBJECTIVE: Several studies indicate an inverse relationship between the sympathetic nervous system activity and thyroid function. Altered adrenoceptor sensitivity, particularly alpha 1 and beta, have been described in hypothyroid and hyperthyroid patients. No information in patients with thyroid disease is available on the main mechanism regulating sympathetic nervous system outflow, ...
Dehkordi O - - 1994
The current study was undertaken to evaluate the effects of cholinomimetic drugs on cocaine-induced central cardiorespiratory depression. Cats anesthetized by urethane (2.0 g/kg) were subjected to topical application at the caudal ventrolateral medullary surface (cVMS) of cocaine and two cholinomimetic pretreatment drugs. The following drug regimens were tested: 37 mM ...
Moore N - - 1994
Urapidil is an antihypertensive agent known to have central 5HT1A agonistic properties in addition to alpha-1 blocking effects. To assess the importance of these effects, we compared the hemodynamic effects of a single oral dose of urapidil (U, 60 mg) with those of prazosin (Pr, 2 mg), clonidine (Cl, 0.15 ...
Galbraith W M - - 1994
Rapid intravenous infusion of GEM 91, a 25-mer phosphorothioate oligonucleotide complementary to the gag site of HIV, in the monkey produces transient decreases in peripheral total WBC and neutrophil counts, hemoconcentration, and a brief increase followed by a prolonged decrease in arterial blood pressure. These changes are preceded by and ...
Feldman J - - 1994
In anaesthetized animals, systemic injection of ET1 at doses from 3 to 100 ng.kg-1 provoked only a transient hypotensive effect. At 300 ng.kg-1 we observed the classical biphasic effect, consisting of a transient lowering of the arterial pressure followed by a long-lasting hypertensive effect. Direct injection of the peptide into ...
Versteeg D H - - 1993
After the i.c.v. administration of 300 pmol ACTH-(1-24) or [Nle4,D-Phe7]alpha-MSH, a long-lasting increase in blood pressure was observed synchronously with the incidence of excessive grooming. Two structurally related peptides with no grooming behavior-inducing potency, ACTH-(7-16)-NH2 and gamma 2-MSH, in doses of 300 and 500 pmol, respectively, caused a slight and ...
Rauck R L - - 1993
BACKGROUND: Intraspinally administered alpha 2-adrenergic agonists may relieve pain in sympathetically maintained pain (SMP) syndromes, such as reflex sympathetically dystrophy (RSD), by spinal, peripheral, and central nervous system actions. This study examined analgesic efficacy and side effects of epidurally administered clonidine in patients with severe, refractory RSD. METHODS: Twenty-six patients ...
Burris J F - - 1993
Cardiovascular diseases are the leading causes of death in the United States, with hypertension being amongst the most prevalent of the cardiovascular risk factors. Improvement of hypertension management has, in consequence, received much attention. Extensive pre- and post-marketing experience with the transdermal formulation of clonidine marketed in the USA in ...
- - 1993
The clonidine patch offers for the first time the unique possibility of a once-a-week transdermal therapy of hypertension due to direct absorption of clonidine through the skin. The present study investigates the efficacy and safety of the transdermal administration on a sample of the Italian population. 101 patients entered the ...
Robertson D - - 1993
BACKGROUND: Baroreflexes originate in the great vessels of the neck and thorax and prevent arterial pressure from rising or falling excessively. METHODS: This study was undertaken to clarify the cause, clinical spectrum, and therapy of this disorder. We studied 11 patients with baroreflex failure presenting as severe, labile hypertension and ...
Watts S W - - 1993
Recent studies indicate that norepinephrine-induced contractile oscillations in the tail artery from stroke-prone spontaneously hypertensive rats (SHRSP) may be a vascular phenomenon independent of blood pressure level. The objectives of this study were: (1) to characterize pharmacologically the alpha-adrenoceptor mediating norepinephrine-induced oscillations in tail artery; and (2) to investigate the ...
Lee F W - - 1993
Intravenous infusions of nitroglycerin (GTN), 1,2-glyceryl dinitrate (1,2-GDN), and 1,3-glyceryl dinitrate (1,3-GDN) were given to four conscious dogs at 10 micrograms/min, 30 micrograms/min, 50 micrograms/min, and 70 micrograms/min of GTN and 20 micrograms/min and 100 micrograms/min of GDNs. The steady state plasma concentrations (Css) of GTN were reached after about ...
Kurihara J - - 1993
The influence of 5-min global cerebral ischemia on the facilitatory modulation of the vagal baroreflex through central alpha 2-adrenoceptors or by the electrical stimulation of the septum was investigated in anesthetized dogs. Reflex bradycardia was produced by a bolus injection of phenylephrine at a dose which produces about a 25-mmHg ...
Houston M C - - 1993
Calcium channel blockers and central alpha-agonists are among the classes of antihypertensive drugs that yield the most favorable overall effects on risk factors for hypertension-related end-organ damage. An open-label prospective trial in 42 patients with a mean baseline blood pressure of 144/102 mm Hg sought to assess the usefulness of ...
Bauer J A - - 1993
Hemodynamic rebound after abrupt withdrawal may be an important consideration associated with nitroglycerin (NTG) monotherapy. This phenomenon may arise from unopposed neurohormonal vasoconstriction because of rapid elimination of NTG. The role of NTG pharmacokinetics in the development of hemodynamic rebound was examined using a rat model of congestive heart failure. ...
Keipert P E - - 1993
This report describes acute changes in systemic blood pressure and urine output observed after a 50-percent isovolemic exchange transfusion (ET) with diaspirin-crosslinked hemoglobin (alpha alpha Hb). Stroma-free Hb was crosslinked between the alpha chains by using a 14C-labeled diaspirin, bis(3,5-dibromosalicyl)fumarate. Forty conscious, chronically cannulated rats underwent ET with 14C-labeled alpha ...
Lefèvre-Borg F - - 1993
1. Phenylephrine-induced contractions of rabbit isolated trigone and urethra were antagonized in a competitive manner by alfuzosin (pA2 7.44 and 7.30, respectively) and prazosin. 2. The characteristics of [3H]-prazosin binding to human prostatic adenoma tissue were evaluated. [3H]-prazosin was potently displaced by alpha 1-adrenoceptor specific agents including alfuzosin, its (+)- ...
Ono H - - 1993
Experiments were performed on intact and spinalized rats anesthetized with urethane and alpha-chloralose. In intact rats, administration of tizanidine (0.1 mg/kg, i.v.) decreased the mono- (MSR) and polysynaptic reflex potentials (PSR). Blood pressure was initially elevated and then lowered by tizanidine. Although pretreatments with hexamethonium and phentolamine prevented the tizanidine-induced ...
Rupniak N M - - 1993
We examined the ability of intravenous (i.v.) challenge with pentagastrin to induce behavioural and cardiovascular effects consistent with panic attack in conscious rhesus monkeys. For behavioural evaluation, 4 naive male rhesus monkeys familiar with minimal manual restraint necessary for drug administration received a rapid i.v. bolus of pentagastrin (4, 8 ...
Grossman E - - 1993
Yohimbine is an alpha 2-adrenoceptor antagonist that is FDA approved for treatment of impotence. The drug is an indolalkylamine alkaloid chemically similar to reserpine and is believed to act through sympatholysis. We examined effects of oral yohimbine on blood pressure (BP) and plasma levels of catechols in patients with essential ...
Doak G J - - 1993
Induction of anaesthesia is often associated with undesirable variations in blood pressure and heart rate. Clonidine has been demonstrated to attenuate many of these undesirable effects when used as a premedicant. Other alpha 2 adrenergic agonists have been used to ameliorate the cardiostimulatory effects of ketamine in animals but there ...
Jastrzebski Z - - 1993
The effect of the GABA agonist muscimol on the hypotensive action of clonidine in SHR was investigated. Muscimol administered before clonidine significantly (p < 0.01) intensified clonidine-induced reduction of blood pressure. This effect was achieved at muscimol doses which themselves had no influence on blood pressure. Muscimol injected after clonidine ...
Harris J - - 1993
In the decerebrated rabbit, intrathecal administration of the alpha 2-adrenoceptor antagonists idazoxan and yohimbine increases reflex responses of gastrocnemius motoneurones to electrical stimulation of the sural nerve. The maximum effect of idazoxan is about twice that of yohimbine, suggesting that part of the effect of idazoxan may be due to ...
Izumi Y - - 1993
The effects of clonidine, a potent alpha 2 adrenergic agonist and an imidazole/imidazoline receptor agonist, were examined in the cat cerebrovascular system, measuring cerebral oxygen and carbon dioxide tension (BrPo2, BrPco2) and arterial blood pressure. Intracarotid injection of clonidine (2 micrograms/kg) produced a gradual decrease in systemic blood pressure without ...
Pollock S H - - 1993
We have reported previously that phenyl-2-aminoethyl sulfide and its derivatives are excellent substrates for dopamine-beta-monooxygenase and produce an antihypertensive effect in spontaneously hypertensive rats after i.p. administration. In the studies reported herein, we demonstrate that alpha-methyl-phenyl-2-aminoethyl sulfide and 4-hydroxy-alpha-methyl-phenyl-2-aminoethyl sulfide, the methylated and hydroxymethylated derivatives of phenyl-2-aminoethyl sulfide, respectively, decrease ...
Yang C H CH Department of Anesthesiology, Chang Gung Memorial - - 1993
The effects of intravenous clonidine, a central adrenergic alpha-2 agonist, on the incidence of shivering and hemodynamic changes after epidural anesthesia were assessed in patients undergoing extracorporeal shock wave lithotripsy (ESWL). Forty ASA class I or II patients were randomly assigned in a double-blind manner to one of two groups. ...
Given M B - - 1993
In the conscious dog, intravenous administration of methionine-enkephalin produces simultaneous increases in both heart rate (HR) and mean arterial blood pressure (MAP). This report describes both depressor and cardioaccelerator responses to methionine-enkephalin (10 micrograms/kg IV) in conscious dogs following acute hypotension induced by either bolus injection of isoproterenol (0.1-5.0 micrograms/kg ...
Polarz H - - 1993
The objective of the study was to assess the effects of premedication with clonidine on intraocular pressure (IOP) after the administration of succinylcholine. Fifty elderly patients undergoing ophthalmic surgery were randomly allocated to two study groups. Group 1 patients (n = 25) received clonidine, 300 micrograms p.o. In group 2 ...
Lin J C - - 1993
In the present study, we evaluated the relationship between hypertension and the antinociceptive effect of clonidine in genetically hypertensive rats. Intraperitoneal (i.p.) administration of clonidine (0.69 mg/kg) produced hypoalgesia without lowering blood pressure in conscious spontaneously hypertensive (SH), spontaneously hypertensive-stroke prone (SH-SP) and Wistar-Kyoto (WKY) rats. The antinociceptive effect of ...
Madeddu P - - 1993
Cadmium, a trace element from natural and industrial sources, may contribute to the pathogenesis of arterial hypertension. We evaluated the effect induced by acute intracerebroventricular (icv) administration of cadmium on mean blood pressure of normotensive conscious rats. Intracerebroventricular cadmium (1 to 10 micrograms) produced a dose-dependent, sustained increase in mean ...
Courtice G P - - 1993
In this study, we investigated the cardiovascular effects of four tachykinins in the anaesthetized toad, Bufo marinus. The potencies were compared of the amphibian peptides ranakinin and physalaemin and the mammalian peptide substance P, all of which interact preferentially with tachykinin NK-1 receptors. Neurokinin B, which is found in both ...
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