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Dobutamine is administered as a racemic mixture consisting of both (+) and (−) isomers; the (+) isomer is a potent β 1 agonist and α 1 antagonist, while the (−) isomer is an α 1 agonist. [9] The administration of the racemate results in the overall β 1 agonism responsible for its activity.
The mechanisms of sympathomimetic drugs can be direct-acting (direct interaction between drug and receptor), such as α-adrenergic agonists, β-adrenergic agonists, and dopaminergic agonists; or indirect-acting (interaction not between drug and receptor), such as MAOIs, COMT inhibitors, release stimulants, and reuptake inhibitors that increase the levels of endogenous catecholamines.
Some substances do both (e.g. dopamine, dobutamine). If low blood pressure is due to blood loss, then preparations increasing volume of blood circulation—plasma-substituting solutions such as colloid and crystalloid solutions (salt solutions) [1] —will raise the blood pressure without any direct vasopressor activity.
Specifically, dobutamine selectively binds to β1 receptors located on the surface of specialised cardiac muscle cells. [16] Relative to β2 receptors, β1 is the predominant type in terms of quantity and function within the heart.
Indications of administration for β agonists include: Bradycardia (slow heart rate) Asthma; Chronic obstructive pulmonary disease (COPD) Heart failure; Allergic reactions; Hyperkalemia; Beta blocker poisoning; Premature labor (this is an off-label use and could be detrimental) [7]
Stress and potential cardiac damage from exercise during the test is a problem in patients with ECG abnormalities at rest or in patients with severe motor disability. Pharmacological stimulation from vasodilators such as dipyridamole or adenosine, or positive chronotropic agents such as dobutamine can be used.
Norepinephrine (noradrenaline). Although complete selectivity between receptor agonism is rarely achieved, some agents have partial selectivity. NB: the inclusion of a drug in each category just indicates the activity of the drug at that receptor, not necessarily the selectivity of the drug (unless otherwise noted).
Dopamine receptors are a class of G protein-coupled receptors that are prominent in the vertebrate central nervous system (CNS) and are implicated in many neurological processes, including motivational and incentive salience, cognition, memory, learning, and fine motor control, as well as modulation of neuroendocrine signaling.