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At least 775 records · Page 43Linked to original sources
PubMed1991

Action of sympathomimetic drugs on the bronchial circulation of the horse.

In the quietly standing horse I.V. administration of adrenaline decreased, and of dobutamine increased, bronchial artery flow. These changes paralleled changes in arterial pressure. With phenylephrine and noradrenaline bronchial artery flow decreased while arterial pressure increased, indicating active vasoconstriction in the bronchial circulation. With clenbuterol an increase in bronchial artery flow was accompanied by a decrease in systemic blood pressure, indicating bronchial arterial vasodilatation. We conclude that alpha-constrictor and beta 2-dilator receptors are present in the bronchial artery bed and that stimulation of these receptors could explain changes in flow seen in the horse during exercise and anaesthesia.

Animals↗
PubMed1973

Interactions between sympathomimetic amines and antidepressant agents in man.

Intravenous infusions of phenylephrine, noradrenaline, adrenaline, and isoprenaline were given to healthy human volunteers after five to seven days on phenelzine, tranylcypromine, or imipramine, and cardiovascular responses were compared with those observed under control conditions. With monoamine oxidase inhibitors there was a 2-2(1/2) fold potentiation of the pressor effect of phenylephrine, but no clinically significant potentiation of cardiovascular effects of noradrenaline, adrenaline, or isoprenaline. With imipramine there was potentiation of the pressor effects of phenylephrine (2-3 fold), noradrenaline (4-8 fold), and adrenaline (2-4 fold); there were dysrhythmias during adrenaline infusions, but no noticeable or consistent changes in response to isoprenaline.Noradrenaline and adrenaline in amounts contained in local anaesthetics used in dentistry are not likely to be significantly potentiated in otherwise healthy patients receiving monoamine oxidase inhibitors. Hazardous potentiation of their cardiovascular effects might occur in patients receiving tricyclic antidepressants.Our observations do not indicate that the hazards associated with isoprenaline inhalation by bronchial asthmatics would be increased by coincident therapy with a monoamine oxidase inhibitor or tricyclic antidepressant.

Adult↗
PubMed1992

Time course of bronchodilating effect of inhaled formoterol, a potent and long acting sympathomimetic.

BACKGROUND: Most of the currently available inhaled beta 2 agonists are short acting bronchodilators. The aim of this study was to compare the rate of onset and duration of the bronchodilating activity of formoterol and salbutamol. METHODS: Fourteen patients with reversible airways obstruction received placebo, 200 micrograms salbutamol, and 12, 24, and 48 micrograms formoterol from a metered dose inhaler, according to a double blind, randomised crossover design. Forced expiratory volume in one second (FEV1) and specific airways conductance (sGaw) were measured over 12 hours. RESULTS: Salbutamol and all doses of formoterol caused a significant and substantial increase in sGaw one minute after inhalation. The mean maximum increase in FEV1 was 58% (8%) after 200 micrograms salbutamol compared with 63% (11%), 62% (10%), and 74% (10%) after 12, 24, and 48 micrograms formoterol, respectively. The mean maximum increase in FEV1 occurred 57 (12) minutes after administration of salbutamol compared with 137 (16), 141 (21), and 161 (33) minutes after 12, 24, and 48 micrograms formoterol respectively. The bronchodilating effect of salbutamol did not differ from placebo after six hours. In contrast, the mean increase in FEV1 12 hours after 12 micrograms formoterol (26% (8%) of baseline) significantly exceeded the change after placebo. Tremor was recorded in four patients after 48 micrograms formoterol. CONCLUSION: Formoterol is a potent, fast acting bronchodilator with a long duration of action.

Adolescent↗
PubMed1975

Structure--activity relations for the acceleration of efflux of noradrenaline from adrenergic nerves in rabbit atria by sympathomimetic amines.

Atria from reserpine-pretreated rabbits were exposed to pargyline to inhibit monoamine oxidase (amine oxidase (flavin-containing) EC 1.4.3.4) and subsequently incubated in (-)-[3H]noradrenaline to allow the cytoplasmic accumulation of amine in adrenergic nerves. The structure-activity relations for acceleration of efflux of cytoplasmic amine were examined. The most potent agents studied were (+)- and (-)-amphetamine, beta-phenethylamine, phentermine, and mephentermine. Ability to accelerate efflux was reduced by addition of phenolic hydroxyl groups, by phenolic methylation, by beta-hydroxylation, and by N-substitution. The structure-activity relations for acceleration of efflux differ notably from those for uptake, inhibition of uptake, or release of noradrenaline from adrenergic nerves, reported in previous studies. The ability and potency of a given phenethylamine derivative to accelerate the efflux of cytoplasmic noradrenaline is probably determined by such factors as the lipid solubility of the amine, the affinity of the amine for the uptake and efflux site(s) for noradrenaline, and competition for any reserpine-resistant intraneuronal binding sites.

Animals↗