Search Results
Results 701 - 750 of 1015
< 10 11 12 13 14 15 16 17 18 19 20 >
Guffanti E - - 1985
The effectiveness and safety of dihydroergotoxine mesylate (DHT) and clonidine (CLO) as acute antihypertensive treatments were studied in a single-blind randomized controlled study of 28 patients hospitalized after abrupt increases in mean blood pressure (MAP) to more than 150 mmHg, with concomitant symptoms related to hypertensive status (16 patients). Intravenous ...
Herman C A - - 1985
The effects of epinephrine (E), norepinephrine (NE), phenylephrine (PHE), and isoproterenol (ISO) were studied in vivo on the blood pressure and heart rate of the conscious American bullfrog, Rana catesbeiana. Bullfrogs were chronically cannulated with a T cannula in the right sciatic artery. In warm-acclimated (22 degrees, W-A) bullfrogs, baseline ...
Schoener E P - - 1985
Earlier work has indicated that the systemic cardiovascular actions of clonidine might be mediated by caudal brainstem centers, especially the nucleus of the solitary tract (NTS). This study sought to define the mode of clonidine action on the NTS more explicitly using the technique of push-pull perfusion on urethane-anesthetized rats. ...
Williams C A - - 1985
The possible involvement of an adrenergic-endorphin system in the mediation of the pressor response to isometric muscular contraction was studied in cats. Fatiguing contractions of the gastrocnemius and plantaris muscles caused an increase in the mean arterial blood pressure by 35 to 70 mmHg. Intravenous infusion (30 micrograms X kg-1) ...
Levin E R - - 1985
To evaluate the role of endogenous opioid peptides in regulating the blood pressure of hypertensive individuals, we administered the opiate antagonist, naloxone. One individual developed a severe hypertensive response, mean arterial pressure rising from a baseline of 107 mmHg to 147 mmHg 145 min after naloxone injection and infusion. After ...
Koda L Y - - 1985
The possible role of medullary somatostatin as a neurotransmitter involved in blood pressure regulation was examined. Blood pressure and heart rate were measured in pentobarbital anesthetized rats while pmol quantities of somatostatin-28 (SS28), SS28-(15-28) (somatostatin-14), SS28-(1-12) or SS28-(1-10) were injected into the caudal nucleus tractus solitarii (NTS). Injection of artificial ...
Otorii T - - 1985
In anesthetized rabbits, intracerebroventricular (ICV) administration of the alpha-adrenoceptor agonist, guanfacine, like clonidine, elicited dose-related falls in arterial blood pressure and heart rate. ICV pretreatment with the histamine H2-receptor antagonist, metiamide, significantly reduced the hypotensive and bradycardic responses caused by ICV injection of either guanfacine or clonidine. The present results ...
Fan S G - - 1985
Intracerebroventricular (i.c.v.) injection of 3-mercaptopropionic acid (3-MP, 250 micrograms/10 microliter) elicited an elevation of blood pressure in a dose-dependent manner in anaesthetized rats. This elevation of blood pressure could be blocked by treatment with amino-oxyacetic acid (AOAA, 25 mg/kg, i.p.) 5 h prior to the i.c.v. injection of 3-MP. Given ...
Sander G E - - 1985
The preproenkephalin A molecule from the adrenal medulla contains the opioid peptides methionine-enkephalin (Met-ENK), leucine-enkephalin (Leu-ENK), methionine-enkephalin-Arg6-Phe7 (heptapeptide), and methionine-enkephalin-Arg6-Gly7-Leu8 (octapeptide). In the conscious, chronically instrumented dog, Met-ENK and Leu-ENK simultaneously increase heart rate and systemic arterial pressure following intravenous administration. In 19 of 23 dogs, heptapeptide produced a response ...
Loomis C W - - 1985
The acute intrathecal (i.t.) administration of 10, 25, 50, and 100 microgram morphine and 7.5, 10, 15, and 30 microgram (-)norepinephrine (NE) to the rat produced dose-dependent, long-lasting analgesia as assessed by the tail-flick and hot-plate tests. For i.t. morphine, maximum analgesia was observed 30-60 min after drug administration. The ...
Charney D S - - 1985
There is preclinical and clinical evidence suggesting that one neural mechanism responsible for antipanic efficacy is a reduction in brain noradrenergic function. Alprazolam, a triazolobenzodiazepine, has been demonstrated to have antipanic properties; however, to our knowledge, its effects on noradrenergic function have not been established. To assess whether alprazolam alters ...
Jain A K - - 1985
Guanfacine, 1 to 3 mg/day, and clonidine, 0.1 to 0.3 mg twice a day, were compared in a 24-week double-blind, randomized, parallel study of 42 patients with hypertension that was inadequately treated by chlorthalidone, 25 mg/day. Mean reduction of blood pressure was 18/9 mm Hg after guanfacine and 14/8 mm ...
Smith L J - - 1985
Chronic administration of clonidine in the drinking water of spontaneously hypertensive (SH) rats from 11 through 17 weeks of age prevented the further development of hypertension in this model. A dosage adjustment (from about 0.1 to 0.5 mg/kg) was required to maintain a stable systolic pressure of about 200 mmHg. ...
Edvinsson L - - 1985
Haemorrhagic hypotension induces the phenomenon of cerebrovascular autoregulation and, concomitantly, involves an activation of the sympathetic nervous system. As brain vessels in cats have an atypical adrenoceptor distribution we studied the effects of an alpha-adrenoceptor antagonist on the autoregulatory response to haemorrhage. Cortical blood flow was studied by the H2 ...
Quail A W - - 1985
The steroid induction agent, Althesin, infused intravenously in light anesthetic doses in otherwise unsedated man (84 micrograms kg-1 min-1) and rabbit (140 micrograms kg-1 min-1) causes similar autonomic and somatic effects. In the rabbit, the rise in heart rate (mainly due to central vagal blockade) and the selective depressant effects ...
Pals D T - - 1985
THE CARDIOVAscular actions of losulazine hydrochloride, a peripheral norepinephrine-depleting agent in rodents, have been determined in conscious cynomolgus monkeys. Acute oral administration of losulazine at 0.1, 1, 10 and 30 mg/kg evoked dose-related hypotensive responses in the absence of significant alterations of heart rate. Although variable, the acute hypotensive effects ...
Schaller M D - - 1985
The antihypertensive effect of clonidine hydrochloride delivered at a constant rate for seven days by transdermal disks was evaluated in seven patients with essential hypertension. Blood pressure values measured at the physician's office were not significantly decreased by one month of treatment with one (n = 2) or two (n ...
Zabludowski J R - - 1985
Ketanserin has been shown to antagonise both alpha 1-adrenergic (alpha 1) and 5-HT2-serotonergic (5-HT2) receptors in animal experiments but the findings in humans have been conflicting. Its mode of action in reducing blood pressure is unclear. We have studied, therefore, the effects of ketanserin 40 mg b.i.d. given orally for ...
Farsang C - - 1985
Analysis of the effect of naloxone (0.4 mg iv.) on clonidine hypotension in 80 patients with essential hypertension revealed that two groups could be separated. In the responding group (43 pts) naloxone increased blood pressure and heart rate in clonidine-treated patients while in the non-responding group (37 pts) it has ...
Sakurai J - - 1985
Clostridium perfringens alpha toxin decreased heart rate, then elevated blood pressure, and finally caused some changes of electrocardiogram readings. The toxin decreased peripheral blood flow before blood pressure started to increase and the blood flow continued to decrease, without any affect on electrocardiogram readings, until the maximal pressure rise caused ...
Staneva-Stoytcheva D - - 1985
An experimental model of the "withdrawal syndrome" in chronic clonidine treatment is reproduced in spontaneously hypertensive rats (SHR). Medication is withdrawn abruptly after daily oral administration of 100 micrograms/kg clonidine for 12 days or after it has been received with the drinking water in a dose of approximately 250 micrograms/kg ...
Woittiez A J - - 1985
Ketanserin is a serotonin antagonist with high affinity for S2-serotonergic receptors, which mediate the vasoconstrictor effects of serotonin. It does not block the vasodilator effects of this monoamine, and it is devoid of agonist activity and serious central side effects. Ketanserin, however, also binds to alpha 1-adrenoceptors. The compound (10 ...
Abrahamsson T - - 1985
In the adrenergic neurons the amino acid alpha-methyl-meta-tyrosine (alpha-MmT) is converted to metaraminol via the noradrenaline (NA) synthetic pathway. Metaraminol thereby displaces NA from its neuronal stores, and as a consequence NA levels can be drastically reduced, although normal sympathetic tone is essentially maintained by release of newly synthetized NA. ...
Magorien R D - - 1985
Regional and central hemodynamic variables were ascertained in 10 patients with congestive heart failure before and after the oral administration of clonidine. Following the 0.2 mg dose, renal, hepatic, and limb blood flow remained unaltered, whereas a reduction was noted in heart rate (10%), mean systemic (14%), and pulmonary capillary ...
Goldstein D S - - 1985
To assess the contribution of sympathetic outflow to blood pressure in patients with essential hypertension, we measured blood pressure and plasma norepinephrine responses to clonidine, an antihypertensive agent that decreases central sympathetic outflow, in 44 patients and in 41 normotensive control subjects of similar age. Among the hypertensive patients, the ...
Hoefke W - - 1985
In anaesthetized rabbits the hypotensive activity of a group of 2,3-disubstituted 2-aryl-imino-imidazolidines was estimated. Compounds with 3-bromo substituents at the phenyl moiety of the molecule are more than or as active as clonidine. Correlations between blood pressure lowering effect and lipophilicity, maximum alpha-adrenergic effects (alpha E') and -log ED50 (pD2') ...
Hoefke W - - 1985
In rabbits, clonidine (200 micrograms/kg) exerted no blood pressure lowering effect after oral administration contrary to the strong decrease in blood pressure after i.v. injection. This surprising effect induced experiments on metabolic degradation of clonidine in the rabbit. After oral administration 14C-clonidine was rapidly almost totally metabolised and only minimal ...
Egan B - - 1985
Since increased alpha-adrenergic reactivity may participate in the pathophysiology of essential hypertension, methods for accurately assessing in vivo alpha-receptor sensitivity in humans might be useful. The goals of this study were to employ previously used methods, namely pupillometry and local forearm intraarterial infusions, to assess alpha-receptor sensitivity, create an in ...
Campbell B C - - 1985
Abrupt withdrawal of the centrally-acting antihypertensive agent, clonidine, is associated with a high incidence of rebound hypertension and tachycardia, with symptoms of sympathetic overactivity and increased catecholamine excretion. Gradual clonidine withdrawal has been recommended, but does not always avoid the reaction. A regimen is described comprising high doses of the ...
Giles T D - - 1985
Central alpha-adrenoceptor agonists (methyldopa, clonidine, guanabenz) decrease sympathetic outflow and renin and vasopressin secretion as well as increase parasympathetic activity. These drugs are commonly employed as antihypertensives. Two other conditions, chronic heart failure and ischemic heart disease, may also benefit from central alpha-adrenergic stimulation. In both acute and chronic heart ...
Lillie C - - 1985
Indoramin is a selective alpha 1-antagonist which reduces blood pressure without reflex tachycardia and can cause a bradycardia. The direct bradycardic effect of indoramin was investigated in various isolated cardiac preparations as well as in the intact cat. In isolated guinea-pig atria indoramin reduced spontaneous atrial rate in concentrations similar ...
Crombie D S - - 1985
The acoustic technique was used in conjunction with the pressure chamber to determine the tensions causing cavitation of xylem sap in leaves of five woody angiosperms (Acer pseudoplatanus L., Alnus glutinosa L. Gaertn., Eucalyptus globulus Labill., Fraxinus excelsior L. and Rhododendron ponticum L.) and three species of herbs (Lycopersicum esculentum ...
Kanniainen E - - 1985
The antihypertensive effects of urapidil and clonidine have been studied in a double-blind cross-over trial in 11 hypertensive outpatients with mild to moderate hypertension, at rest and during isometric exercise. Urapidil 30 mg b.i.d. significantly decreased the standing diastolic blood pressure (p less than 0.05) and the systolic blood pressure ...
Lilja M - - 1985
Haemodynamic effects of atenolol 50 mg, clonidine 0.15 mg, and prazosin 5 mg, given twice daily, and of the combinations atenolol + prazosin and clonidine + prazosin were studied in 8 hypertensive outpatients. Measurements were made at rest, during isometric sustained handgrip and submaximal ergometer work in mostly double-blind and ...
Morales-Olivas F J - - 1984
The effect of an 8-alpha-amino-ergoline-derivative, CU 32-085, recently characterized as a dopamine agonist, was studied on blood pressure and heart rate in normotensive anesthetized rats. The effects of CU 32-085 and bromocriptine on dose-response curves to sympathomimetic agents (adrenaline, noradrenaline, methoxamine and clonidine), intravenously administered, were also studied. CU 32-085 ...
Hamilton B P - - 1984
The incidence and pathogenesis of withdrawal phenomena with the centrally acting drugs clonidine (CLON) and tiamenidine (TIAM) were evaluated. Thirty subjects with hypertension on hydrochlorothiazide (HCTZ) were randomized to TIAM or CLON. Blood pressure and integrated plasma catecholamine levels fell equally in response to both drugs. On withdrawal, blood pressure ...
Kellar K J - - 1984
We studied the effects of urapidil, clonidine, and prazosin on ligand binding to central nervous system receptors in rats and on arterial pressure and heart rate in chloralose-anesthetized cats. Ligand binding studies indicated that urapidil had 90 times greater affinity for alpha 1 than for alpha 2 adrenergic receptors. Administration ...
Hubbell F A - - 1984
The acute and chronic effects of fixed dosages of clonidine and prazosin on supine and upright blood pressure, the renin-angiotensin-aldosterone system, and plasma catecholamines were compared in 24 patients with essential hypertension. The patients were randomized into two groups; 11 received chlorthalidone (50 mg daily) throughout the protocol, but 13 ...
Beck A - - 1984
The effects of prazosin (0.1, 0.5 and 2.5 mg/kg, orally) on blood pressure, heart rate and PRA were investigated after acute and chronic administration in conscious, normotensive dogs. The acute administration of prazosin caused a reduction in both systolic and diastolic blood pressure and an increase in heart rate and ...
Abrams W B - - 1984
This symposium reviewed the fundamental principles, pharmacology, and clinical pharmacology of central alpha-adrenergic blood pressure regulating mechanisms. Fundamental principles Arterial baro- and chemoreceptor signals reach the nucleus of the tractus solitarius (NTS) via vagal and glossopharyngeal afferents. The NTS communicates with sympathetic preganglionic neurons in the spinal cord via centers ...
Petursson G - - 1984
A single regular (70 microL) or mini (15 microL) eyedrop of 0% (placebo), 0.25%, and 0.50% strengths of clonidine hydrochloride was administered to 16 patients with open-angle glaucoma in a double-masked crossover study. Both the regular drops and minidrops of 0.25% and 0.50% concentrations of the drug substantially lowered the ...
Ghose K - - 1984
Tyramine, an indirectly acting sympathomimetic amine, can be used as a pharmacological tool to assess the peripheral adrenergic activity and its interactions with drugs in man. Of the various techniques used, the tyramine pressor test appears to be the most reliable method. It is convenient to perform and carries no ...
Bousquet P - - 1984
Blood pressure was studied in pentobarbital anesthetized rats and cats after central administration of ouabain. Intracerebroventricular (i.c.v.) injections caused a classical biphasic effect, a short lasting hypotension followed by a hypertensive phase. When injected directly into the nucleus reticularis lateralis region (NRL), ouabain (0.01-2 micrograms/kg) caused a dose-dependent pressor effect. ...
Weber M A - - 1984
The efficacy of transdermal clonidine, alone and in combination with diuretics, has been demonstrated in several studies involving patients with mild to moderate essential hypertension. In one 3-month open study, 64% of patients (wearing one to three 3.5 cm2 transdermal patches) achieved sustained blood pressure reductions throughout the treatment period. ...
Guyenet P G - - 1984
Spinally-projecting A5 noradrenergic neurons were recorded in urethane-anesthetized rats. All A5 neurons sampled were inhibited by raising the mean arterial blood pressure (mBP) in the 110-160 mm Hg range. Similar elevations of mBP in baroreceptor-denervated rats were without effect. Clonidine inhibited A5 neurons and enhanced the inhibitory effect of increasing ...
Farsang C - - 1984
Naloxone [0.4 mg iv.] increased blood pressure and heart rate of 13 clonidine-treated [0.3 mg per os for 3 days] patients with essential hypertension [reacting group] while it has no such effect in 11 clonidine-treated patients [non-reacting gr.] Clonidine increased plasma beta-endorphin concentration of the reacting patients by 17.53 +/- ...
Siever L J - - 1984
The authors measured plasma 3-methoxy-4-hydroxyphenylglycol (MHPG), plasma norepinephrine, blood pressure, and heart rate responses to the alpha 2-adrenergic agonist clonidine in 25 depressed patients and 25 normal control subjects. In the control subjects clonidine reduced plasma norepinephrine, blood pressure, and heart rate significantly more than placebo. In the depressed patients ...
Leaton R N - - 1984
The unique effect of clonidine in facilitating habituation of the acoustic startle response [10] was replicated. However, clonidine had no effect on between-session habituation, showing a pharmacological dissociation between short- and long-term habituation. Systematic manipulation of ISI showed clonidine's habituation-facilitating effect to be most striking with longer within-session ISIs where ...
Livnat A - - 1984
A long-term (14-24 h) telemetry recording of mean arterial pressure (MAP) and heart rate (HR) was obtained from conscious unrestrained dogs (n = 9) maintained in a closed environment. MAP and HR records were analyzed for their harmonic content by the fast Fourier transform method. The power spectral density functions ...
Carli G - - 1984
This study is an attempt to detect the most important modifications of physiological parameters occurring during pressure immobility in rabbits and to compare them with those recorded during animal hypnosis. Like the latter, pressure immobility is characterized by the development of high voltage slow waves in the EEG, reduction in ...
< 10 11 12 13 14 15 16 17 18 19 20 >