Flashcards in CV Stimulants Deck (85)
What are some CV stimulants?
What does stimulation of beta receptors in the heart (B1) lead to?
-accelerated SA/AV node (HR up)
-accelerated ectopic pacemakers
What does stimulation of beta receptors in skeletal muscle vasculature lead to?
relaxation via preventing the entry of calcium that is critical to the contraction of vascular smooth muscle.
What does binding of epinephrine or NE to β adrenoceptors result in?
Stimulates adenylyl cyclase by activating the stimulatory G
protein, Gs, which leads to the dissociation of its alpha subunit charged with GTP. This activated αs subunit directly activates adenylyl cyclase, resulting in an increased rate of synthesis of cAMP.
What does binding of epinephrine or NE to a2 adrenoceptors result in?
Binding of presynaptic alpha2-adrenoceptor ligands inhibits adenylyl cyclase by causing dissociation of the inhibitory G protein, Gi, into its subunits; ie, an activated αi subunit charged with GTP and a β-γ unit.
The mechanism by which these subunits inhibit adenylyl cyclase is uncertain.
cAMP binds to the regulatory subunit (R) of cAMP-dependent protein kinase, leading to the liberation of
active catalytic subunits (C) that phosphorylate specific protein substrates and modify their activity.
Which receptors are linked to the Gq protein?
Which receptors are linked to the Gi protein?
Which receptors are linked to the Gs protein?
Which sympathomimetic agents act on a-receptors?
-Epi (locally vasoconstrict)
-DA (at higher dose)
Which sympathomimetic agents act on B-receptors?
-DA (at higher dose)
Sympathomimetic drugs are classified based upon their mechanism of action either in the pre-synaptic terminal or on the post-synaptic membrane. What do direct acting drugs do?
stimulate postsynaptic receptors
What do indirect acting drugs do?
Indirectly-acting drugs cause an increase of E or NE via:
- causing release from pre-synaptic terminals
- blocking transport into sympathetic neurons (cocaine)
- blocking metabolizing enzymes
What are some stimulant metabolizing enzymes?
-monoamine oxidase (MAO)
Drugs that cause a release of neurotransmitter, but they also themselves stimulate the receptors are called what?
What are some direct acting selective adrenergic agonists?
please call dad tomorrow
What are some direct acting non-selective adrenergic agonists?
a1/2, B1/2 Epi
a1/2, B1- Nor
T or F. Both selective and non-selective direct acting adrenergic agnostic are not reduced by reserpine pretreatment
T. May actually increase because NE induces changes that up-regulate receptors or enhance signaling pathway
What are some mixed acting adrenergic agnostic?
Is Ephredrine reduced by prior treatment with reserpine?
Effects are blunted, but not abolished
What are some indirect acting adrenergic agonists?
How do MAOIs or COMTIs cause indirect effects?
By preventing the breakdown of released
How doe Tyramine and Amphetamine cause indirect effects?
cause the release of preformed transmitter that is normally stored successfully in the presynaptic vesicles
What does reserpine do?
depletes NE from sympathetic neurons
Does pretreatment with reserpine affect the effects of indirect adrenergic agonists?
Yes, abolishes them
What is the receptor specificity for Dobutamine?
B1 more than B2, alpha
What are the uses of Dobutamine?
HF (ino over chrontropic), stress tests
What is the receptor specificity for DA?
D1=D2 more than B more than alpha
What are the uses of DA?
-inotropic and chronotropic effects predominate at high doses
What is the receptor specificity for Epi?