Autonomic Pharmacology 4 Flashcards
In blood vessels, are alpha or beta adrenoreceptors associated with Gi?
alpha = Gi
In blood vessels, are alpha or beta adrenoreceptors associated with Gs?
beta = Gs
What is the effect of alpha2 receptor stimulation in blood vessels?
vasodilation –> decrease peripheral resistance –> reduce BP
Which adrenoreceptor(s) is/are associated with skin and spleen blood vessels and capacitance vessels? Does binding at this/these receptor(s) cause constriction or dilation?
skin and spleen blood vessels and capacitance vessels are associated with ALPHA1
alpha1 –> constriction
Which adrenoreceptor(s) is/are associated with muscle blood vessels? Does binding at this/these receptors cause constriction or dilation?
muscle blood vessels are associated with ALPHA1 and BETA2
alpha1 –> constriction
beta2 –> dilation
What effect does presynaptic alpha2 stimulation/binding have on NA release in blood vessels?
What effect does presynaptic beta receptor stimulation/binding have on NA release in blood vessels?
presynaptic alpha2 –> decrease NA
presynaptic beta –> increase NA
What is the main adrenoceptor found in the heart?
beta1 is the main adrenoreceptor in the heart
What is the effect of adrenoreceptor binding/stimulation in the heart?
increased Ca2+ influx –> increased force and rate of contraction –>. increased conduction of A-V node (palpitations)
Why do beta agonists pose a cardiac risk?
since beta adrenoreceptor binding stimulates the heart (e.g. palpitations), beta agonists can cause SEVERE CARDIA DYSRHYTHMIAS
Which adrenoreceptor(s) stimulate the radial pupil dilator muscle of the iris? What is the effect of stimulation?
- alpha receptors
- stimulation causes mydriasis/dilation
Which adrenoreceptor is found on bronchiole smooth muscle? What is the effect of stimulating this adrenoreceptor?
- beta2
- relax bronchiole smooth muscle
What adrenoreceptor is found in nasal blood vessels? What is the effect of stimulating this receptor? Would it be easier or harder to breathe if the receptor is stimulated? Why?
- alpha receptor
- stimulation causes vasoconstriction
- stimulation makes it easier to breathe because vasoconstriction decreases blood flow, which decreases inflammation and opens up the nose
What is the effect of alpha agonists in the GI tract? What is the effect of beta agonists in the GI tract?
alpha and beta both cause relaxation in the GI tract
How do alpha2 agonists affect the GI tract?
indirect relaxation of GI tract via decreased release of ACh
Do alpha agonists promote or inhibit micturition? What is the mechanism?
inhibit micturition by constricting the bladder
What is the effect of an alpha2 agonist on insulin and renin release? what about a beta2 agonist?
alpha agonist –> inhibit insulin and renin release
beta agonist –> stimulate insulin and renin release
What is the effect of beta3 stimulation in fat cells?
promote lipolysis
What is the effect of beta stimulation in liver?
promote glycogenolysis
Name a non-selective sympathomimetic. (hint: it’s a catecholamine)
adrenaline (epinephrine)
What is the effect of adrenaline binding to alpha receptors in skeletal muscle blood vessels?
vasoconstriction
What is the effect of adrenaline binding to beta2 receptors in skeletal muscle blood vessels?
vasodilation
What is the therapeutic effects of adrenaline as a vasoconstrictor?
-vasoconstrictor mixed with anaesthetics prolongs nerve block duration
-vasoconstriction prevents loss of anaesthetics into systemic circulation
-treat anaphylaxis
Name 4 indirectly acting sympathomimetics.
Tyramine, Cocaine, Amphetamines, Tricyclic Antidepressants
Which sympathomimetic exhibits the cheese effect?
Tyramine
