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Therapeutics P2 > exam 2 lecture 5 > Flashcards

exam 2 lecture 5 Flashcards

1
Q

what are ion channels

A

Proteins that form pores on plasma membrane

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2
Q

Three ways ion channels are categorized

A

gating (opening and closing mechanism)
ion selectivity
Pharmacology

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3
Q

which ion channel is most selective

A

K channels

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4
Q

two tyoes of ion chnnnales that are categorized by gating

A

Ligand gated
voltage gated

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5
Q

are ion channels active or passive

A

Passive

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6
Q

Difference between ion channels and trasnporter

A

ion channels are pores that respond to stimulus (voltage, Ach) to open them. The ions will pass through the channel and flow down their electrochemical gradient. NO ENERGY REQUIRED

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7
Q

What determines direction of flow for ions

A

Concentration gradient
Electrical gradient

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8
Q

membrane potential

A

98 mv

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9
Q

excitable cells have what kind of potential across the membrane? why is that?

A

Excitable cells have a negative inward potential across the membrane

This is due to selective permeability of resting membrane to K

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10
Q

Levels of K inside and outside of cell

A

High inside cell (155mm)
low outside (4mm)

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11
Q

Levels of Na inside and outside of the cell

A

Low inside the cell (12)
high outside

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12
Q

how is gradient Na and K gradient maintained

A

By active trasnport of Na out and K into cell.

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13
Q

Levels of free Ca2+ inside vs outside of the cell

A

Free Ca2+ is very low inside cell (100nm)
High outside of cell (1.5mm)
15,000 fold difference

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14
Q

what is the role calcium channels play in myscle contraction

A

When Na rushes into the cell and depolarizes it, Ca channels open. And they stay open, FOR A LONG TIME(broad action potential). This is where contraction occurs (broad part of calcium channels opening)

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15
Q

why is K channel so selective?

A

because of its selectivity filter. potassium ion makes contact with carbonyls that strip the water of ion as it passes through filter. (it is called a long pore due to long narrow passage)

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16
Q

Open vs closed shape of K channel

A

V is closed
/\ is open

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17
Q

most important target for calcium channel blockers

A

Ca v 1.2

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18
Q

what will happen if we block Ca influx through Ca v 1.2

A

It will inhibit contraction of cardiac and vascular muscle

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19
Q

what is the use of calcium channel blockers

A

Used to block Ca V 1.2 channels in vasculature and create VASODILATION to relax smooth muscle.

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20
Q

effect of calcium channel blockers on BP and Angina

A

Lower BP and relieve angina

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21
Q

Use of blocking of channels in cardiac muscle and SA/AV node

A

It is ANTIARRHYTHMIC

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22
Q

what is CICR

A

calcium inducedd calcium release

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23
Q

Explain CICR mechanism

A

Ca2+ influx via Ca v 1.2 induces release of Ca from intracellular stores via RYR2 in SR

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24
Q

what does RYR2 do

A

indices release of calcium stores in SR

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25
Use of Ca release in SR
Drives contraction of muscle
26
how does epinephrine affect Ca V 1.2
Epinephrine binds to B receptor in heart andgenerates phosphorylation of Ca V 1.2 and increases Ca influx. Leads to 1. greater contraction force 2. increased AV nodal action potential (Increased HR)
27
difference in vascular smooth muscle contraction and cardiac muscle and skeletal muscle for Ca required
extracellular Ca is required for vascular smooth muscle and cardiac muscle. Not for Skeletal muscle
28
how does volatage gated calcium channel lead to vascular smooth muscle contraction
-Calcium comes in -releases calcium from stores by activating RYR2, increasing intracellular Ca concentration -Ca binds calmodulin and activates Myosin LC kinase -myosin LC kinase phosphorylates myosin LC - Phosphorylated Myosin lc combines with actin and initiates contraction
29
how does volatage gated calcium channel lead to cardiac muscle contraction
-Calcium comes in -releases calcium from stores by activating RYR2, increasing intracellular Ca concentration (these two steps similar in vascular muscle) -In cardiac muscle (and skeletal muscle) Ca ions are released from SR and bind Troponin C - Ca binding by troponin C causes displacement of tropomyosin, allowing actin to bind to myosin. leading to contraction
30
how does volatage gated calcium channel lead to skeletal muscle contraction
Extracellular Ca not required. Ca V 1.1 and RYR 1 used instead of 1.2 and RYR 2 -Ca ions are released from SR and bind TroponinC - Ca binding by troponin C causes displacement of tropomyosin, allowing actin to bind to myosin. leading to contraction
31
similarity and difference of vascular, cardiac and skeletal contraction
vascular and cardiac have similar 1st 2 steps --Calcium comes in -releases calcium from stores by activating RYR2, increasing intracellular Ca concentration Cardiac and skeletal have similar last 2 steps -Ca ions released from SR and bind troponin C - Ca binding of troponin c causes displacement of troponin C allowing myosin and actin to bind Skeletal muscle extracellular Ca not required, but is required for cardiac and vascular muscle. skeletal uses CaV 1.1 and RYR 1, Cardiac and vascular use CAV 1.2 and RYR 2
32
Name the 3 calcium channel blockers
Dihydropyridines Phenyalkylamines Benzothiazepines
33
Indication and use of CCB (Calcium channel blockers)
HTN, arrythmia, angina
34
Name DHP drugs (how to recognize the name)
-dipine Amlodipine Nimodipine Clevidipine Nifedipine
35
KNOW STRUCTUREE FOR DHP (dihydropyridine)
Has
36
KNOW STRUCTURE FOR AMLODIPINE AND NIMODIPINE
37
Why is amlodipine special
Ether group side chain and primary amine
38
Use of ether group side chain in amlodipine
Give it characteristics of very slow onset and very long duration of action
39
Why is Nimodipine special
It has an ether group and is EXTREMELY hydrophobic
40
What is the use of extreme hydrophobia of Nimodipine
Nimodipine can be used to relax the vascular muscle within an area of hemorrhage (bleeding) to try and restore blood flow due to its hydrophobia.
41
Why is clevidipine special
half life is short and is given IV
42
why is clevidipine half life short? What is contraindicated
Breaks down rapidly due to esterase Not given in patients with soybean or egg sensitivity
43
Tissue selectivity of DHP (vascular or smooth) What do DHPs work well in
High degree of selectivity for relaxing vascular smooth muscle. not a strong effect on cardiac muscle. Work well in coronary arterty
44
what is the reason for the vascular smooth muscle selectivity viewed in DHP
difference in membrane potential property. vascular smooth muscle tends to have a more depolarized resting membrane potential than cardiac muscle
45
Is DHP voltage dependent? Why?
Prefers the more depolarized vascular smooth muscle over the cardiac smooth muscle
46
DHP binding site
They do not bind in the pore, they bind on an allosteric site outside of pore
47
do DHP have tonic or frequency dependent block
Tonic
48
How does DHP work
Bind to closed channels and prevent opening
49
DHP effect on peripheral resistance
Reduction of peripheral resistance
50
Effect of DHP on venules and arterioles
Dilation of arterioles Little effect on venules
51
Which DHPs are vasoselective
Amlodipine, nifedipine, felodipine, nislodipine, isradipine
52
effect of DHP on afterload and on HR or force of contraction
Decreased afterload and little effect on HR and force of contraction.
53
reflex tachycardia is caused by all DHPs except for
Amlodipine
54
Nimodipine exhibits selectivity for_________. What is it used in?
nimodiine exhibits selectivity for cerebral arteries. Used to prevent neuropathy
55
how do DHPs show efficacy in angina
reduce O2 demand in heart
56
T/F all DHPs undergo first pass effect T/F DHPs are highly bound to protiens
True for both
57
which DHP could depress cardiac function? what happens when this DHP is promptly released?
Nifedipine. Prompt release nifedipine solutions may increase risk of subsequent heart attack
58
What is the only phenylalkylamine drug
Verapamil
59
What does phenylalkylamine do?
Causes vasodilation.
60
Which one causes more vasodilation (more potent) DHP or verapamil (phenylalkylamine)
DHP more potent
61
What can Verapamil (phenylalkylamine) do that DHP can not
Increase HR and force of contraction
62
is there reflex tachycardia in phenylalkylamine (verapamil)
It is blunted
63
is verapamil (phenylalkylamine) tonic block or frequency dependent
Frequency dependent block
64
What is the use of verapamil being frequency dependent
It is useful in arhythmias
65
Where does verapamil bind
Binds the pore (entry) not allosteric site. In order to bind, the drug has to get inside pore to bind.
66
Name benzothiazepine drug
DIltiazem
67
is diltiazem (benzothiazepine) frequency dependent or tonic block
Exhibits both a little bit
68
Which one inhibits the heart rate more? DHP, Verapamil or diltiazem
Verapamil the most, diltiazem next, last is DHP
69
Which one causes the most vasodilation? DHP, verapamil or diltiazem
DHP (second is diltiazem)
70
Which one causes tachycardia DHP, Verapamil or diltiazem
Non-amlodipine DHPs cause most tachycardia. Second is Diltiazem
71
Which ones slow conduction through SA and AV node? DHP, Verapamil or Diltiazem
Verapamil (most ) and diltiazem (second)
72
which ones treat super ventricular arrythmias? DHP, Verapamil or Diltiazem?
Verapamil and Diltiazem
73
Why do verapamil and diltiazem treat ventricular arrythmias
Because they are frequency dependent
74
Which CCB (calcium channel blocker) suppress HR? why?
Diltiazem and Verapamil
75
How does DHP affect HR
increases it through reflex tachycardia
76
Why do diltiazem and verapamil lower HR
Due to frequency dependent kinase
77
DHP effect summary on HR, AV conduction, myocardial contraction and arterial vasodilation
HR- increase (only one to increase hr) No effect on AV conduction No effect on myocardial contraction Best at DILATING arterial vasodilation
78
Verapamil summary on effect on HR, Av conduction, Myocardial contraction, Aretrial vasodilation
HR- Lowers HR (the most) Lowers AV conduction Lowers Myocardial contraction Raises arterial vasodilation
79
Diltiazem Summary on HR, Av conduction, Myocardial contraction, aretrial vasodilation
Lowers HR Lowwers AV conduction Lowers Myocardial contraction Raises Arterial vasodilation
80
which CCB has no effect on Myocardial contraction and AV conduction
DHP
81
which CCB is the best as arterial vasodilation
DHP
82
DHP side effets
Facial flushing, tachycardia, ankle edema (ankle edema is on all CCBs)
83
Verapamil side effects
Constipation and ankle edema
84
Diltiazem side effects
Ankle edema

Therapeutics P2 (41 decks)

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