Biomedical Engineering Reference
In-Depth Information
Table 5.15.
Main features of CMC sodium carriers.
Fast activating
Influx
Voltage- and time-dependent opening
Scarce in sinoatrial node
−
,−
Hyperpolarization activated
Slow opening at [
40 mV]
Depolarization of pacemaker
Stimulation by catecholamines and cAMP
Inhibition by ACh
60
Background
Inward flux
Attenuation of resting membrane potential
Activated by increase in cytosolic [Ca
2
+
]
i
3Na
+
vs. 1 Ca
2
+
Early Ca
2
+
influx
Na
+
influx in late plateau
NCX
Na
+
-K
+
pump
3 Na
+
vs. 2 K
+
Minor contribution to resting potential
Table 5.16.
Main features of CMC calcium and chloride carriers.
Calcium carriers
Voltage-gated
Ca
V
3 activated at more negative potential
than Ca
V
1.2 channel
Early plateau current (Ca
V
1.2)
Ca-Induced Ca Release (Ca
V
1.2)
SAN and AVN action potential (Ca
V
1.2)
Pacemaker depolarization (Ca
V
3)
Fast inactivation (Ca
V
3)
Ca
2
+
AT P a s e
E ffl u x
Chloride carriers
cAMP-dependent
Stimulation by cAMP,
1 agonists
Phase 1 repolarization after
β
β
1 activation
Ca
2
+
-dependent
Stimulation by cytosolic Ca
2
+
Phase 1 repolarization
Pacemaker potential
Stretch-activated
Opening by osmotic swelling
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