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.Pharmacology > Part 24: Beta-Blockers and Sympatholytics > Flashcards

Part 24: Beta-Blockers and Sympatholytics Flashcards

1
Q

at a cellular level, cardiac contraction and the movement of blood between the chambers of the heart and eventually out into circulation is achieved by what is known as _____

A

excitation-contraction coupling

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2
Q

AP are generated by the ____ node and propogated by the _____ system in the heart

A

SA; electrical conduction

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3
Q

once an AP reaches the cardiac muscle cells in the atria and ventricles, the membrane depolarization causes ____ channels to open, which causes more depolarization and the openinf od ____ channels

A

Na; Ca

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4
Q

the influx of Ca interacts with receptors on the _____ to cause _____ to be released. This process is called _____

A

SR; stored Ca; calcium induced Ca release

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5
Q

the large concentration of Ca in the cytoplasm of the cardiac myoscytes interacts with _____ to cause cardiac muscle contraction

A

contractile fibers (myofilaments)

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6
Q

what happens when all of the heart cells contract together?

A

the whole heart contracts and pumps blood out of the chambers in a coordinated way

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7
Q

t/f the larger the amount of intracellular Ca, the larger the cardiac contraction

A

t

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8
Q

when the sympatholytic nervous system is activated, the release of _____ activates B1 adrenergic receptors in the heart

A

catecholamines (NE and Epi)

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9
Q

B1 receptors are G____ coupled and their activation leads to increased concentrations of ____ and ____

A

S; cAMP and PKA

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10
Q

what is the effect of Ca and contraction of heart cells when activated by B1?

A

increased intracellular Ca through the channels, resulting in a forceful cardiac contraction

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11
Q

sympathetic activation causes the SA node to fire AP _____(faster or slower)

A

faster

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12
Q

sympathetic activation makes the heart pump ____ and ___ (harder and faster or weaker and slower)? Does this increase of decrease cardiac output?

A

faster and harder ; increased cardiac output and increased BP

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13
Q

what are 3 ways to target the sympathetic activation of the heart?

A
  1. centrally target the sympathetic nervous system in the brain
  2. target the B adrenergic receptors
  3. target the Ca channels
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14
Q

what is the MOA of clonidine?

A

centrally acting antihypertensive agent that acts as an agonist at Alpha 2 adrenergic receptors in the brain to reduce sympthetic input to the heart

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15
Q

the alpha 2 receptor is primarily expressed on ____ neurons and acts as a ____ receptor

A

presynaptic ; auto

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16
Q

stimulation of the alpha 2 receptor by an endogenous NT like NE or Epi regulates the release of _____ and regulates the propogation of _____ between neurons and ultimately modulates the sympathetic effects in target tissues

A

additional NT; signals

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17
Q

clonidine stimulates Alpha 2 receptors in the ____ neurons, particulary in the _____, activating G___ coupled signalling cascade

A

central; medulla; i

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18
Q

when clonidine activates the Gi signalling cascade, it ____(raises/lowers) the amount of NE being released from the central neurons, which ____ (increases/decreases) sympathetic tone

A

lowers; decreases

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19
Q

what does a decrease in sympathetic tone do bronchodilation, vasoconstriction, and cardiac output?

A

less bronchiodilation, less vasoconstriction, reduced CO

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20
Q

clonidine acts in the ____, which is the part of the brain responsible for regulating cardiac function

A

medulla

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21
Q

t/f clondine may act on off target alpha 2 receptors (not in the medulla) and this can cause off target effects

A

t

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22
Q

what are the most commonly observed side effects of clonidine?

A

headache, hypotension, dizziness, fatigue, nausea and othe rcentral nervous effects

23
Q

the actions of clonidine on the CNS may be beneficial for patients with ____

A

ADHD

24
Q

how is it belived that clonidine may help with ADHD?

A

modulating NE release from adrenergic neurons may help to restore some balance between neuronal circuits in teh prefrontal cortex to help with attention

25
Q

t/f clonidine may also be helpful in the management of pain and drug use disorder (opioids and nicotine)

A

t

26
Q

why cant normotensive patients use clonidine for pain, ADHD and substance abuse disorders?

A

bc clonidine can cause hypotension even in pts with high BP, so its too dangerous for normotensive patiensts

27
Q

t/f due to its ability to cause too much BP reduction, often resulting in hypotension, clonidine is often not used unless several other options have been tried and failed

A

t

28
Q

what is the effect of clonidine on the vascular smooth muscle?

A

decreases peripheral resistance

29
Q

what is the effect of clonidine on the heart?

A

decrease HR and contractility

30
Q

beta blockers block the B1 receptors in the heart ____ (competively or non-competively)

A

competitively

31
Q

most of the differences between different drugs of the beta blocker class are related to differences in ____

A

receptor selectivity

32
Q

how do beta blockers lower BP?

A

prevent release of PKA which causes release of Ca which causes heart contraction, which increases BP

33
Q

why is it important that beta blockers bind competively to the B1 receptor?

A

bc we still need sympathetic activation to work when its needed, like when we are exercising

34
Q

why can epi still increase BP when a patient is on a beta blocker?

A

epi is also an agonist of the alpha 1 receptors that also cause vasoconstriction to increase BP

35
Q

whn a pt is given Epi while on a beta blocker, ____ can increase, but ____ should not increase

A

BP; heart rate/contractility

36
Q

blocking alpha 1 receptors in the _____ and B1 receptors in the ____ has an additive antihypertensive effect

A

BV; heart

37
Q

give an example of a mixed A1/B1/B2 drug used for hypertensive (greatest affinity for a1 and b1)

A

carvediol

38
Q

patients with what conditions should not take carediol?

A

asthma and COPD bc it may block B2 and reduce the bronchodilation needed in the lungs; as well those with orthostatic hypotension shouldnt take it due to the blocking of a1

39
Q

of the a1, b1, b2 receptors, what is the order from greatest to least affinity of carvediol?

A

b1>a1>b2

40
Q

carvediol binds ____ (reversibly/irreversibly) to the adrenergic receptors

A

reversibly

41
Q

what is teh prototypic beta blocker?

A

propranolol

42
Q

why is propranolol not commoly used anymore?

A

its not selective, so it can affect the B2 in the lungs and we dont like that

43
Q

____ is an example of a cardioselectibe B blocker

A

metoprolol

44
Q

t/f the selectivity of metoprolol is dose-dependent; if the dose is high enough, it can start to target the B2 receptors

A

t

45
Q

the affinity of metoprolol for B1 is estimated to be _____X greater than for the B2 receptor

A

2-6

46
Q

why is the term “cardioselective” beta blocker misleading?

A

there are B1 receptors in areas of the body other than the heart and these drugs can target these peripheral receptors as well

47
Q

B1 receptors are also found in the kidneys, where their activation leads to the secretion of ____

A

renin

48
Q

what is the effect of beta blockers blockign the B1 receptors in the kidneys?

A

reduced renin, reduced aldosterone so decreased blood volume and less vasoconstriction = more bp lowering

49
Q

_____ is an example of a Ca channel blocker that acts in BOTH the vascular smooth muscle and cardiac cells

A

diltiazem

50
Q

what is the effect of diltiazem blocking the Ca channels in teh SA node of the heart?

A

decrease in AP genration and lowers heart rate

51
Q

what is the effect of diltiazem blocking the Ca channels in the atrial and ventricular myocytes

A

reduced force of contraction

52
Q

t/f diltizem prevents the compensatory increase in heart rate

A

t

53
Q

t/f non-DHP Ca blockers like diltiazem are typically not the 1st line for hypertension but may be used if other treatments have failed

A

t

.Pharmacology (55 decks)

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