coupling

Question 1

similarities in skeletal and cardiac muscle

Answer 1

1. contraction elicited by increase in myoplasmic calcium concentration
2. intracellular store (SR) is main source Ca2+
3. release Ca2+ originates at t-tubule

Question 2

Cardiac Muscle:

ECC requires

Answer 2

1. entry of external Ca
2. CaV1.2 (α1C)
3. β2a or β2b
4. α2δ1 RyR2

Question 3

Skeletal Muscle: ECC require

Answer 3

1. DOES NOT REQUIRE entry of external Ca
2. CaV1.1 (α1S)
3. β1a
4. α2δ1, γ1 RyR1

Question 4

how does SERCA2 remove calcium

Answer 4

Ca diffuses within SR to terminal cisternae, where it binds to calsequestrin (low affinity, high capacity)

Question 5

why does SERCA2 dominate?

Answer 5

since SR surrounds each myofibril; requires less energy since VSR≈0.

Question 6

cardiac muscle, Ca2+ is released from SR by

Answer 6

RyR2

Question 7

skeletal muscle, Ca2+ is released from SR by

Answer 7

RyR1

Question 8

in both skeletal and cardiac, Ca2+ binds to

Answer 8

troponin on thin filaments and activates contraction

Question 9

Expression of Cav1.1 or Cav1.2 in

Answer 9

dysgenic myotubes

Question 10

Relaxation:

Answer 10

SERCA>NCX»PMCA

Question 11

NCX driven depolarization, secondary to _____, has been suggested to be important for ____

Answer 11

diastolic SR Ca release

pacemaking of SA nodal cells.