Biomedical Engineering Reference
In-Depth Information
Table 6.12.
Io
n channels, genes, and currents of the sinoatrial node (Source: [
441
]).
Current
Channel subunits
Genes
Voltage-gated Na
+
channels
i
Na
Na
V
(
α
)1.1/2/5 SCN1A/2A/5A
Na
V
β
1/2/3 SCN1B/2B/3B
Voltage-gated Ca
2
+
channels
i
Ca
,
L
Ca
V
(
α
)1.2/1.3
CACNA1C/D
Ca
V
β
1/2/3
CACNB1/2/3
Ca
V
α
2
δ
1/3
CACNA2D1, CACNA2D3
Ca
V
γ
5
CACNG5
i
Ca
,
T
Ca
V
(
α
)3.1 CACNA1G
Voltage-gated K
+
channels
i
K
,
to
K
V
(
α
)1.4
KCNA4
K
V
(
α
)4.2/4.3
KCND2/3
KChIP2
KCNIP2
MiRP1
KCNE2
i
K
,
ur
K
V
(
α
)1.5
KCNA5
K
V
β
1/2
KCNAB1/2
i
K
,
r
K
V
(
α
)11.1
KCNH2
MiRP1
KCNE2
i
K
,
s
K
V
(
α
)4.3
KCNQ1
Mink
KCNE1
i
K
,
b
K
2P
2.1 (TREK1)
KCNK2
K
2P
3.1 (TASK1)
KCNK3
i
K
ACh
K
IR
3.1/4
KCNJ3/5
i
K
AT P
K
IR
6.2
KCNJ11
Hyperpolarization-activated, cyclic nucleotide-gated channels
i
f
HCN1/2/4
Hcn1/2/4
MiRP1
KCNE2
Na
+
-K
+
pump
i
NaK
AT P
α
1/2/3
ATP1A1/2/3
β
1
ATP1B1
Na
+
-Ca
2
+
exchangers
i
NaCaX
NCX1
SLC8A1
the cardiac frequency, hence yielding an additional mechanism with respect to
i
f
current [
607
]. A threshold of
AR activity is required to engage CamK2 kinase.
In ventriculomyocytes, CamK2 acts on Ca
2
+
flux from and into sarcoplasmic
reticulum. It is able to increase Ca
2
+
filling into and release from the sarcoplasmic
reticulum, as it phosphorylates SERCA inhibitor phospholamban (positive lusitropic
effect) and RyR2 (positive inotropic effect), respectively. Kinase CamK2 thus allows
maintenance of mechanical performance of ventriculomyocytes during sustained
(24 h) catecholamine stimulation. In sinoatrial cells, CamK2 is necessary for
β
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