Pharmacology: anti-arrythmics class 2,3 & adenosine

Question 1

describe the action of class 2 anti-arrythmics

Answer 1

beta blockers, block phase 4 of myocyte action potential

Question 2

describe effect of class 2 anti-arrythmics

Answer 2

decrease sympathetic activity on heart, reduces intracellular cAMP and hence reduces Ca influx

Question 3

describe action of class 3 anti-arrythmics

Answer 3

K channel blockers

Question 4

give an example of a class 3 anti-arrythmic

Answer 4

amiodarone

Question 5

describe effect of class 3 anti-arrythmics on myocyte action potential

Answer 5

block phase 3 and prolong action potential duration by increasing refractory period

Question 6

give an example of a class 4 anti-arrythmic

Answer 6

verapamil

Question 7

describe action of class 4 anti-arrythmics

Answer 7

Ca channel blocker

Question 8

what effect do class 4 anti-arrythmics have on myocyte action potentials

Answer 8

block phase 2

Question 9

describe action of adenosine

Answer 9

induces transient heart block on AV node

Question 10

when would adenosine be used

Answer 10

used to identify rhythms