1.5, 1.6 Adrenergic Pharmacology Flashcards
SNS stimulation mediated by release of __________ which activates adrenoceptors
norepinephrine
sympathomimetic drugs mimic the actions of?
epinephrine or norepinephrine
- promote release of endogenous catecholamines
- displace stored catecholamines (amphetamine and tyramine)
- inhibit reuptake of catecholamines (cocaine)
indirect acting agents
- in peripheral vasculature: contract smooth muscle, increase blood pressure
- PLC activation, IP3 - calcium mobilization, DAG -PKC activation
alpha 1 adrenoceptors
presynaptic autoregulation of neurotransmitter release, inhibit adenylyl cyclase activity
-decrease intracellular cAMP levels
alpha 2 adrenoceptors
- approximately equal affinity for epi and NE
- found in vasculature, lung, eye, and most other end organs
- increase cAMP levels
beta 1 adrenoceptors
- high affinity for epi than NE
- found in vasculature, lung, eye, and most other end organs
- increase cAMP levels
beta 2 adrenoceptors
- important in the brain
- found in splanchnic and renal vasculature
- D1 stimulates, D2 inhibits adenylyl cyclase
dopamine receptors
-_______ may limit therapeutic response to sympathomimetics
desensitization
Sympathomimetic drugs: in blood vessels alpha receptors __________ arterial resistance, and beta2 receptors __________ vascular smooth muscle
increase
relax
skin and splanchnic vessels have primarily _____ receptors
alpha
skeletal muscle vessels have predominantly _______ receptors
beta 2
sympathomimetics:
- in the heart _______ receptor activity predominates
- activation results in increased calcium influx in cardiac cells, AV conduction velocity increased, refractory period decreased
beta-1
______ agonists in the eye contract the radial pupillary dilator muscle –> mydriasis (dilation), can slighlty increased drainage of aqueous humor
alpha
_______ agonists in the eye increase aqeuous humor secretion by the ciliary epithelium, antagonists are important in the treatment of glaucoma
beta agonists
in the respiratory tract, ________ relax bronchial smooth muscle
beta 2 receptors
in the respiratory tract, ______ receptors in blood vessels of upper respiratory mucosa produce decongestion upon contraction
alpha 1
in the GI tract, _______ receptors on smooth muscle cells mediate relaxation
-alpha 2 activation ________ PNS drive on enteric nervous system
beta
decreases
in the GI tract, alpha-1 receptors _______ the bladder base, promoting urinary retention
contract
in the GU tract, beta 2 receptors of bladder wall _____ smooth muscle, promoting urinary retention
relax
increase lipolysis
enhance glycogenolysis
increase glucose release
increase insulin secretion
beta receptor activation
______ receptor activation decreases insulin resistance
alpha-2
- very potent vasoconstrictor (alpha-1) and cardiac stimulant (beta-1)
- positive inotropic and chronotropic actions on heart (beta-1)
- also activates beta-2 receptors
- mixed effects on TPR, increases venous capacitance
epinephrine
- effects similar to epi on alpha-2 receptors in the heart
- similar potency at beta-1 receptors
- relatively little effect on beta-2 receptors
- increases peripheral resistance
- increases both diastolic and systolic blood pressure
- compensatory vagal reflexes overcome positive direct chronotropy, at high doses may directly increase HR
norepinephrine
potent nonselective beta receptor agonist –> positive chronotropic and inotropic actions –> increases cardiac output
-decreases both diastolic and mean arterial pressures
isoproterenol
activates D1 receptors in renal vasculature, increases renal blood flow
dopamine