Drugs affecting the vasculature and blood pressure Flashcards Preview

Cardiovascular: pharmacology > Drugs affecting the vasculature and blood pressure > Flashcards

Flashcards in Drugs affecting the vasculature and blood pressure Deck (114)
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1

what is the role of endothelial cells?

provide a diffusion barrier but also inhibits platelet activation

more importantly - it can control the relaxation and contraction of smooth muscle cells

2

how do smooth muscle cells contract? the mechanisms is essentially the same as airway smooth muscle. Step 1-

calcium enters

3

how does calcium enter the SMC?

L-type channels or GPCR q11

4

what does calcium bind to once in the SMcell?

calmodulin

5

what does the Ca/calmodulin do?

converts MLCK into active MLCK

6

what does active MLCK do?

phosphorylates MLC causing contraction

7

which molecules is responsible for relaxation in SMC?

cGMP

8

what does cGMP do?

coverts MLC phosphatase into active form

9

what does active MLC phosphatase do?

dephosphorylaes MLC causing relaxation

10

which substances act on the endothelium to cause vasodilatation?

bradykinin
ADP
5HT

11

what do vasodilators on endotheliam dio?

allow GPCR to let in Ca into the cell ?

12

what does Ca in endothelial cells do?

binds to calmodulin

13

what does the Ca calmodulin complex do in endothlelial cells ?

activates nitric oxide synthase

14

what does nitric oxide synthase do?

converts L-arginine and oxygen to NO and citrulline

15

what does the NO producedby the endothelial cells then do?

diffuses into the SMC neighbouring it

16

what does NO in SMC do?

activates guanylate cyclase which converts GTP to cGMP

17

what does cGMP do?

causes relaxation through mechanism previously

18

what else can cGMP do?

activate protein kinase G activates Ca dependent K channels - causing K to leave and thus hyperpolarisation

19

what do organic nitrates do?

when metabolised they relesase NO into SMC and cause relaxation as above

20

in small doses what do organic nitrates do?

cause venorelaxation - decreases SV

21

what does small doses of organic nitrates do to the HR?

increase it so CO is maintained the same

22

what do organic nitrates do in larger doses?

cause arteriolar dilatation

23

what does arteriola dilatation cause?

decreases the arterial pressure so reduces afterload
- also decreases pulse wave reflection

24

why are organic nitrates useful in angina?

they cause decreased myocardial oxygen requirement via
1) decreased preload
2) decreased afterload
3) improved perfusion of the ischaemic zone

25

how do Organic nitrates cause improved perfusion to ischaemic zones?

they cause dilatation of collateral vessels

26

what are organic nitrates used in?

angina and acute coronary syndrome

27

what is the danger in unstable angina?

danger that a cap of atheromatous plaque is going to form a thrombus

28

what are the two examples of ONs?

GTN and Isosorbide mononitrate

29

what is GTn most effective in?

prevention rather than relief

30

what is the acting time?

short acting 30 mins