sem B - drugs acting on smooth muscle

Question 1

what determines smooth muscle contraction

Answer 1

phosphorylation of myosin light chain

Question 2

dephosphorylation of myosin light chain - is smooth muscle relaxed or contracted

Answer 2

relaxed

Question 3

phosphorylation of myosin light chain - is smooth muscle relaxed or contracted

Answer 3

contracted

Question 4

dephosphorylation of myosin light chain - myosin head interacts/doesn’t interact with actin

Answer 4

myosin head doesn’t interact with actin

Question 5

phosphorylation of myosin light chain - myosin head interacts/doesn’t interact with actin

Answer 5

myosin head interacts with actin forming crossbridge

Question 6

what enzyme phosphorylates myosin light chain so smooth muscle contracts

Answer 6

active MLC kinase

Question 7

what enzyme dephosphorylates myosin light chain so smooth muscle relaxes

Answer 7

MLC phosphatase

Question 8

what activates active MLCK (enzyme that phosphorylates MLC) so smooth muscle contracts

Answer 8

calcium binding to calmodulin

Question 9

what activates MLCP (enzyme that dephosphorylates MLC) so smooth muscle relaxes

Answer 9

calcium desensitisation

Question 10

what inhibits MLCP (enzyme that dephosphorylates MLC) so smooth muscle contracts

Answer 10

calcium sensitisation

Question 11

vascular smooth muscle - what’s released in blood that makes VSM contract

Answer 11

angiotensin-2 and adrenaline

Question 12

vascular smooth muscle - what’s released by endothelium that makes VSM relax

Answer 12

nitric oxide

Question 13

vascular smooth muscle - what’s released by sympathetic nerve fibres that makes VSM contract

Answer 13

noradrenaline that activates a1 adrenoreceptors

Question 14

VSM contraction - hormones (adrenaline, noradrenaline, angiotensin 2) binds to GPCR. GPCR causes (1,2)

Answer 14

1. PLC to break down PIP2 into IP3 + DAG
2. rho kinase to inhibit MLCP - calcium sensitisation

Question 15

VSM contraction -
- IP3 causes …… to release calcium
- DAG causes ….. to cause release of Na+ and Ca2+

Answer 15

IP3 causes SR to release calcium
DAG causes ROCC to cause release of Na+ and Ca2+

Question 16

ROCC releases Na+ causing membrane depolarisation and …. to release calcium

Answer 16

VOCC

Question 17

drugs reducing BP cause vasodilation of VSM (relaxation/contraction) reducing TPR

Answer 17

relaxation

Question 18

drugs reducing BP include: a1 adrenoreceptor anatagonists eg. ….. inhibit vasoconstriction produced by noradrenaline

Answer 18

prazosin

Question 19

drugs reducing BP include: b1 adrenoreceptor antagonists (beta-blockers) eg. …. inhibit effects of SNS, decreasing CO

Answer 19

propranolol

Question 20

drugs reducing BP include: VG calcium channel blockers eg. …..

Answer 20

nifedipine

Question 21

drugs reducing BP include: diuretics which ..

Answer 21

increase fluid loss through kidneys decreasing blood volume

Question 22

drugs reducing BP include: drugs that inhibit/activate the RAAS

Answer 22

inhibit

Question 23

how do drugs inhibit RAAS to treat hypertension - inhibit ….. so angiotensin I is not converted to angiotensin II - build up of bradykinin causing dry cough

Answer 23

ACE

Question 24

how do drugs inhibit RAAS to treat hypertension - ….. receptor is blocked so angiotensin II can’t bind to it

Answer 24

AT1 receptor

Question 25

endothelium derived relaxing factor =

Answer 25

NO gas released by endothelium causing vasodilation (VSM relaxation)

Question 26

what happens if you inhibit NO release from endothelial cells

Answer 26

increased BP

Question 27

drugs that enhance actions of NO (VSM relaxation): what do nitrovasodilator drugs do and what do they treat

Answer 27

decompose in blood to release NO, angina but too short acting to be used to treat hypertension

Question 28

drugs that enhance actions of NO (VSM relaxation): what do PDE-5 inhibitors do and what do they treat

Answer 28

stops breakdown of cGMP, prolonging its actions, erectile dysfunction & pulmonary hypertension