Calcium-induced calcium release Flashcards
The structure of _____ ______ ______ is crucial to excitation contraction coupling
cardiac muscle fibres
The Ca2+ release channels of the junctional SR are positioned just under ____ of the T tubule surface membrane
LTCC
The Ca2+ release channels of the junctional SR are positioned just under the LTCC of the ______ surface membrane
T-Tubule
The Ca2+ release channels of the ________ ______ are positioned just under the LTCC of the T-Tubule surface membrane
junctional SR
The Ca2+ release channels of the junctional SR are positioned just under the LTCC of the T-Tubule surface membrane
organised as release units - _____
dyad
The Ca2+ release channels of the junctional SR are positioned just under the LTCC of the T-Tubule surface membrane
each dyad consists if:
10-25 _____
100-200 _________
10-25 LTCC
100-200 “foot proteins”`
The Ca2+ release channels of the junctional SR are positioned just under the LTCC of the T-Tubule surface membrane
Dyadic organisation ensures what
LTCC and RyR are very close together to maximise the efficiency of the CICR
The Ca2+ release channels of the junctional SR are positioned just under the LTCC of the T-Tubule surface membrane
Dyadic organisation ensures that LTCC and RYR are very close together, why?
to maximise the efficiency of CICR
Ca2+ release from the SR is in the form of sparks
“sparks” occur spontaneously or can be evoked by what
depolarisation of cell patches, single isolated cells
Ca2+ release from the SR is in the form of sparks
“sparks” occur spontaneously or can be evoked by depolarisation of cell patches, single isolated cells. They occur in where
intact cardiac muscle
Ca2+ release from the SR is in the form of sparks
Evoked at ‘Z lines’ (SR junctional contact with transverse tubules, RyR clusters/LTCC dyad
Ca2+ release from the SR is in the form of sparks
Evoked by single L-type Ca channel current
vgoltage and time-dependant of Ca spark propbability is similar to that of what
L type Ca channels
Normal CICR is a global summation of
sparks
Ca2+ removal from the cytoplasm allows what
relaxation
Ca2+ removal from the cytoplasm allows relaxation
3 means:
Back into the SR -
SarcoEndoplasmic Reticulum Ca2+ ATP-ase (SERCA)
Ca2+ removal from the cytoplasm allows relaxation
3 means:
Back into the SR - SarcoEndoplasmic Reticulum Ca2+ ATP-ase (SERCA)
Out of the cardiomyocyte -
sodium calcium exchanger (NCX)
Ca2+ removal from the cytoplasm allows relaxation
3 means:
Back into the SR - SarcoEndoplasmic Reticulum Ca2+ ATP-ase (SERCA)
Out of the cardiomyocyte - sodium calcium exchanger (NCX)
Out of the cardiomyocyte -
PlasmaleMmal Ca2+ ATP-ase (PMCA)
SERCA2a, regulated by what
endogenous inhibitor (phospholamban
SERCA2a phosphorylation of PLB by _____ and or _____ relieves endogenous inhibition
PKS and/or CamKII
NCX is an electrogenic __________
transporter
NCX is an electrogenic transporter
Normal mode Ca2+ = ______
how many Na in
Ca2+ exits
3Na in
NX is an electrogenic transporter
Reverse mode
Ca2+ ______
how many Na in
Ca2+ entry
3Na out
The amount of Ca2+ in the SR is very sensitive to whether the cardiomyocyte _____ or _____ Ca2+
gains or loses
SERCA is a pump and it will move Ca2+ in the _____ regardless of the concentration gradient
SR
SERCA is a pump and it will move Ca2+ into the SR regardless of what
of the concentration gradient
Any gain or loss of Ca2+ from the cardiomyocyte is reflected in the SR ______ ______
CA2+ content
CA2+ entry via LTCC and exit via ___ acts to maintain SR Ca2+ content
NCX
Spontaneous Ca2+ release occurs during what
SR overload
Spontaneous Ca2+ release are propagating sparks
Increased SR Ca2+ content increases:
Spark ______
Spark_______
frequency and amplitude
Spark frequency and Spark Amplitude increase when what
increased SR Ca2+ content
Spontaneous Ca2+ release are propagating sparks
Increased SR Ca2+ content increases:
Spark Frequency
Spark Amplitude
When these sparks overcome local CA2+ buffering capacity, they can activate neighbouring ______ clusters
RyR2
Spontaneous Ca2+ release are propagating sparks
Increased SR Ca2+ content increases:
Spark Frequency
Spark Amplitude
When these sparks overcome local CA2+ buffering capacity, they can activate neighbouring RyR2 clusters and set up a _______ ____ of CA2+ release
propagating wave
Spontaneous Ca2+ release are propagating sparks
Increased SR Ca2+ content increases:
Spark Frequency
Spark Amplitude
When these sparks overcome local CA2+ buffering capacity, they can activate neighbouring RyR2 clusters and set up a propagating wave of CA2+ release, this can cause ______ _____ _______ and set up re entrant arrhythmias
delayed after depolarisations
