1 - Antiarrhythmics

Question 1

Pacemaker cells = _____-dependent spikes

Ventricular myocytes = _____-dependent spikes

Question 2

Pacemaker cells are _______ (electrically)

Answer 2

physiologically polarized

Question 3

___ mediates upstroke of pacemaker cell

Answer 3

i_Ca

Question 4

i_Ka

Answer 4

K⁺ current (gated by Ach) activated by vagus

–> OPPOSES i_f during phase 4

Question 5

Pacemaker cell cascade

Answer 5

B-AR –> a-GTP –> AC –>

cAMP -> HCN channel (sodium influx)

cAMP -> pkA –> Phosphorylation of L-type Ca⁺ channel

Question 6

M1R cascade (Ach)

Answer 6

Gai –X–> A.C. –> slow HCN and L-Ca++ channels

Question 7

Myocyte upstroke

Answer 7

I_Na

Question 8

Transient outward current is phase __ and mediated by ____

Answer 8

phase 1

i_Kto = sharp brief repolarization

Question 9

Plateau of myocyte is from

Answer 9

i_Ca(L)

Critical for muscle contraction

Question 10

Voltage gated sodium channel - phase 0

Answer 10

Open

Question 11

Voltage gated Na channel - inactivated

Answer 11

Open, but has h domain blocking outet

Question 12

What gives rise to AP refractory period

Answer 12

the rate of inactivation of voltage-gated Na+ channels

(configuration going from inactivated → rest)

Question 13

Dominates during phase 2 of myocyte contraction

Answer 13

L type Ca channels

Question 14

Dominates during phase 3 of AP

Answer 14

voltage gated K channel