Autonomic Modulators Flashcards
Where does the synthesis of NE happen?
Liver, presynaptic cytoplasm, vesicles
What part of the synthesis of NE happens in the liver?
Phenylalanine to tyrosine
What part of the synthesis of NE happens in the presynapic cytoplasm?
tyrosine to dopa to dopamine
What part of the synthesis of NE happens in the vesicle?
Dopamine to NE to epi
What is the effect of alpha 1 agonism?
Increased intracellular calcium –> smooth muscle contraction, sphincter contraction, vasoconstriction, bronchoconstriction, uterine contraction
What is the effect of alpha 2?
Decreased exocytosis of NTs.
Causes smooth muscle relaxation and vasodilation
CNS sedation
What are the effects of Beta 1?
Increased adenylate cyclase: increased HR, contractility, and conduction
What are the effects of Beta 2?
Bronchodilation Vasodilation Uterine relaxation Relaxation of bladder and gut Increased glycogenolysis, lipolysis, gluconeogenesis and insulin release
Which receptors does epi act on?
Alpha 1, Beta 1 and 2
What are the effects of epi?
Increased contractility, CO, and O2 demand
Decreased SVR (B2)
Increased cerebral and coronar perfusion
Decreased splanchnic and renal perfusion
What receptors does norepi act on?
Alpha 1 and Beta 1 (acts more on alpha)
What are the effects of norepi?
Increased SVR, contractiliy, CO, HR
What are the effects of dopamine at low levels?
Increased urine output via vasodilation of renal vessels Decreased aldosterone Increased CO (B1)
What are the effects of dopamine in the moderate range (2-10 ugm)?
Mainly Beta effects:
Increased contractility
Coronary O2 demand is higher than supply
What are the effects of dopamine in high doses?
Mostly alpha effects: vasoconstriction, bronchoconstriction, uterine constriction.
Predisposes myocardium to ventricular arrythmia
What are the effects of ephedrine?
Increased CO, HR and BP
What is the MOA of ephedrine?
SNS mimetic - indirectly releases NE
What receptors is isoproterenol acting on?
B1 and B2
What are the effects of isoproterenol?
Increased HR, contractility, O2 demand and decreased SVR.
O2 demand exceeds supply because of drop in diastolic BP
What receptors does dobutamine act on?
Beta 1
What are the effects of dobutamine?
Primarily increased CO and contractility
What receptor does phenylephrine act on?
alpha 1
What are the effects of phenylephrine?
vasoconstriction, reflex brady, increased afterload and BP
What receptor is methyldopa acting on?
alpha 2
What receptor is clonidine acting on?
alpha 2
What are the effects of methyldopa?
Produces false NTs which activate alpha 2 receptors and causes a decrease in SNS stimulation –> vasodilation and lower BP
What are the effects of clonidine?
Direct alpha 2 agonist
Sedating properties are effective for lowering anesthetic requirements intraoperatively.
What is clonidine used for?
As an adjunct in regional anesthesia for increased quality an duration of nerve blocks
What receptor does dexmedotomidine act on?
alpha 2
What are the effects of dexmedetomidine?
More potent alpha 2 agonist than clonidine
Initial HTN then brady and hypotension
Sedating and analgesic
lowers anesthetic requirement
What is the MOA of nitroprusside?
metabolized to NO
What are the effects of nitroprusside?
Vaso and venodilation
Decreased afterload, preload and BP while CO and RBF are well maintained
Reflex tachy
Decreased O2 demand on the heart
What are the cerebral effects of nitroprusside?
increased CBF and ICp
What are the pulmonary effects of nitroprusside?
Dilates pulmonary vessels causing pulm. a. pressure to be lowered and decreasing the shunt fraction
How is nitroprusside metabolized?
Receives an electron from hemoglobin resulting in methemoglobin and then a nitroprusside free radial –> cyanide
What are the signs of cyanide toxicity?
arrythmia, metabolic acidosis, and increased mixed venous oxygen content
What is the tx of cyanide toxicity?
Mechanical ventilation of 100% O2
Sodium nitrate to make methemoglobin which will bind cyanide
Sodium thiosulfate to bind cyanide
What are the effects of nitroglycerin?
Decreased preload through venodilation
Increased coronary perfusion
Antiplatelet effects
What is a possible side effect of nitroglycerin?
Methemoglobinemia
What is the MOA of hydralazine?
Vasodilator
What is atropine?
A tertiary amine that can cross the bb barrier ad the placenta
What is a potential side effect of atropine at toxic doses?
CNS stimulation: hallucination, irritability, nervousness
What is atropine known to cause?
Fever
What are the CV effects of anticholinergics?
Tachycardia by blocking vagal stimulation
Shortened PR interval
What are the pulmonary effects of anticholinergics?
Decreased airway secretions
Relaxes bronchial smooth muscle
What are the cerebral effects of anticholinergics?
Excitation or depression
What are the GI effects of anticholinergics?
Decreased salivation, motility, peristalisis
What are the GU effects of anticholinergics?
Urinary retention
What are the effects of anticholinergics on sweat glands?
Inhibits sweat glands so may have increased basal body temp
what are the uses of glycopyrrolate?
decrease salivation and respiratory secretion
Why can’t glycopyrrolate cross the bb barrier?
It is a quaternary structure
What does scopolamine cause that atropine does not?
Sedation