sympathomimetic drugs

Question 1

endogenous catecholamines

Answer 1

epi
norepi
dopamine

Question 2

direct acting alpha receptor agonist (4 )

Answer 2

phenylephrine
methoxamine
clonidine
methyldopa

Question 3

direct acting beta receptor agonist (6)

Answer 3

dobutamine 
isoproterenol 
albuterol
metaproterenol
salmeterol 
terbutaline

Question 4

mixed acting sympathomimetics

Answer 4

ephedrine

pseudoephedrine

Question 5

indirect acting sympathomimetics

Answer 5

amphetamine
tyramine
cocaine

Question 6

sympathetic nervous system - whats released and receptors

Answer 6

postgang sympathetic fibers -> norepi acts on alpha and beta receptors

+ sweat glands -> ACh-> muscarinic

dopamine is also released from postgangl -> renal vasodilation at D1 receptors

Question 7

alpha- 1 adrenergic receptors

tissue and action

Answer 7

radial muscle (eye) - increase Ca, contraction-> dilation
symp synapse in blood vessels -> increase Ca, contraction -> increase BP
GI / bladder: sphincters - increase Ca, contraction
GI wall : relaxation ( indirect via enteric)
salivary glands : increase Ca, increase secretion

Question 8

alpha- 2 adrenergic receptors

tissue and action

Answer 8

presynaptic - decrease cAMP autoregulatory

pancreas - decrease cAMP, inhibit insulin release

Question 9

Beta 1 adrenergic receptor

tissue and action

Answer 9

Heart -> increase HR , FOC and conduction
Kidney - increase renin release
eye - increase aqueous humor production
salivary- enhances amylase secretion

all increase cAMP

Question 10

Beta 2 adrenergic receptor

tissue and action

Answer 10

bronchi - relax
blood vessel wall - relax  
GI/bladder walls - relax 
liver, skeletal muscle- gluconeogenesis , glycogenolysis  
pancreas - slight insulin secretion 

all increase cAMP

Question 11

beta 3 adrenergic receptors

tissues and action

Answer 11

fat cells increase cAMP and lipolysis

Question 12

signal transduction system alpha 1

Answer 12

7 transmembrane receptors coupled to guanine nucleotide binding proteins

• Gq-> increase in phospholipase C-> increase IP# and DG
• IP3 causes release of intracellular Ca++ and DG activates protein kinase C-> phosp and activate proteins

Question 13

signal transduction system - alpha - 2

Answer 13

coupled to inhibitory G-protein termed Gi

-> inhibits adenylate cyclase -> decrease cAMP ( cAMP normally activates protein kinase-> phosp and regulates proteins)

Question 14

signal transduction systems b adrenergic receptors

Answer 14

all coupled to stimulatory g-protein (Gs)

stimulates adenylate cyclase -> increase cAMP

Question 15

receptor desensitization (4)

Answer 15

long term- occurs over days or hours and involves transcriptional or translational changes

short term: maybe due to phosphorylation of the receptor

homologous: receptor becomes unresponsive to own agonist-> when adrenergic receptors +agonist -> substrate for g-protein coupled receptor kinase phosphorylates receptor and increases affinity B arrestin and g protein interaction does not happen and it leads to endocytosis and degradation
heterologous: -> desensitization of 1 receptor also leads to desensitization of another receptor. REceptor activates kinase that phosphorylates another receptor

Question 16

cardio - alpha -1 activation

Answer 16

increase intracellular Ca2+ within vascular smooth muscle cells -> activates myosin light chain kinases + phosphorylates myosin

• sensitize filaments to Ca2+ by inhibiting myosin phosphatase
• contraction of arterial resistance vessels and decrease in venous capacitance
• vasoconstriction in skin and splanchnic vessels
• increase in BP and reflec brady ( gang blockers or antimus block this)

over stimulation -> hemorrhage due to increase BP

Question 17

ccardio - activation of alpha 2

Answer 17

occurs when norepi is released into synapse and will lead to a decrease in release

• decrease symp output leads to decrease bp
• direct stimulation on blood vessels -> vasoconstriction

Question 18

cardio- activation of beta -1 receptors

Answer 18

thru cAMP - phosphorylation of alpha 1 subunit of Ca channels- > increase inward flow of Ca2+ cAMP phosphorylates troponin C which increase sensitivity of contractility

increase Ca2+ -> chronotropic , inotropic and dromotropic effects

overstimulation -> arrhythmias

Question 19

cardio - activation of beta 2 receptors

Answer 19

vasculature relaxation/ vasodilation

- phosphorylation and inhibition of myosin light chain kinase