| Cell Size/Structure |
|
| Size |
Increased length and width (17) |
| Membrane capacitance |
Increased (24) |
| Sarcolemmal Ion Channels |
|
| INa
|
No changes (15, 35)
Steady-state inactivation shifted right (15)
Slightly reduced current density (36)
Late current increased (36) |
| ICaL
|
Reduced current density by ~50% (5, 11, 12, 18, 40)
No changes in voltage dependence of activation and inactivation (11) |
| If
|
Increased mRNA levels (44) |
| Ito
|
Reduced density -80% in the RA -45% in the LA (5, 12, 15, 24, 45-47) |
| IKur
|
Reduced density -55% in the RA -45% in the LA (5, 24, 45, 47, 49)
Unchanged (12, 15, 46) |
| IKs
|
Increased 2-fold (24) |
| IK1
|
Upregulated +100% (5, 12, 13, 15, 45) |
| IK,ACh
|
Increased basal current by receptor-independent, constitutively active component; increased (15) or reduced carbachol-activated current (13, 56, 57) |
| IKATP
|
Decreased (60)
Increased (61) |
| Ca+ and Na+ handling |
|
| INCX
|
Upregulated (17, 18, 21, 34) |
| SERCA |
Reduced maximal pump rate (18) and protein expression (34) |
| PLN |
Enhanced PKA and CaMKII phosphorylation (34)
Unaltered CaMKII-dependent phosphorylation (17) |
| RyR |
Increased phosphorylation at PKA and CaMKII sites (17, 18, 67) resulting in increased channel open probability (68) and SR Ca2= leak (17, 111) |
| INKA
|
Unchanged function (65) |
| Ankyrin-B |
Downregulated (70) |
| Protein kinases and phosphatases |
|
| CaMKII |
Increased expression (32) and phosphorylation (17) |
| PKA |
Similar activity in cAF vs. sinus rhythm (34) |
| PP1, PP2A |
Higher activity (34) |
| Myofilaments |
Reduced maximum rate of tension generation and
maximum active tension, reduced passive tension, and
increase in myofilament Ca+ sensitivity (9)
No changes in maximum force and passive force,
reduced rate of tension redevelopment (71)
Increased phosphorylation of cMyBP-C (9)
Decreased phosphorylation of cMyBP-C (34)
No changes in cTnI phosphorylation (9, 34) |
