Indirect-acting adrenergic agonists potentiate the effects of endogenous catecholamines through different mechanisms without directly binding to adrenoceptors.
One mechanism involves depleting stored catecholamines by displacing them from synaptic vesicles. These agents, known as "displacers," are transported into vesicles at the expense of noradrenaline. Examples include amphetamine and tyramine, which lack a catechol moiety, resulting in prolonged action, improved oral bioavailability, and better penetration into the central nervous system. Amphetamine stimulates cardiac adrenoceptors and releases nonvesicular dopamine and noradrenaline. Tyramine, found in fermented foods, mimics sympathetic responses in individuals taking MAO inhibitors.
Another mechanism is the inhibition of catecholamine reuptake, enhancing the sympathetic response. Cocaine, a local anesthetic, blocks catecholamine transporters, acting as an indirect sympathomimetic. Drugs like cocaine and amphetamine can be addictive due to their CNS stimulatory effects, releasing dopamine and serotonin.
Enzyme inhibitors like MAO inhibitors (e.g., selegiline) and COMT inhibitors (e.g., entacapone) are also indirect-acting agents, as they prevent the breakdown and excretion of circulating neurotransmitters.
来自章节 6:
Now Playing
Drugs Acting on Autonomic Nervous System: Adrenergic Agonists and Antagonists Agents
1.5K Views
Drugs Acting on Autonomic Nervous System: Adrenergic Agonists and Antagonists Agents
3.4K Views
Drugs Acting on Autonomic Nervous System: Adrenergic Agonists and Antagonists Agents
2.2K Views
Drugs Acting on Autonomic Nervous System: Adrenergic Agonists and Antagonists Agents
1.4K Views
Drugs Acting on Autonomic Nervous System: Adrenergic Agonists and Antagonists Agents
1.5K Views
Drugs Acting on Autonomic Nervous System: Adrenergic Agonists and Antagonists Agents
1.4K Views
Drugs Acting on Autonomic Nervous System: Adrenergic Agonists and Antagonists Agents
657 Views
Drugs Acting on Autonomic Nervous System: Adrenergic Agonists and Antagonists Agents
2.5K Views
Drugs Acting on Autonomic Nervous System: Adrenergic Agonists and Antagonists Agents
705 Views
Drugs Acting on Autonomic Nervous System: Adrenergic Agonists and Antagonists Agents
723 Views
Drugs Acting on Autonomic Nervous System: Adrenergic Agonists and Antagonists Agents
803 Views
Drugs Acting on Autonomic Nervous System: Adrenergic Agonists and Antagonists Agents
533 Views
Drugs Acting on Autonomic Nervous System: Adrenergic Agonists and Antagonists Agents
516 Views
Drugs Acting on Autonomic Nervous System: Adrenergic Agonists and Antagonists Agents
528 Views
Drugs Acting on Autonomic Nervous System: Adrenergic Agonists and Antagonists Agents
405 Views
See More
版权所属 © 2025 MyJoVE 公司版权所有,本公司不涉及任何医疗业务和医疗服务。