kristin lewis, dvm pathology resident/graduate research associate
DESCRIPTION
The Myofilament Ca 2+ Sensitizer Levosimendan Preserves Systolic Function in Rats with Volume Overload Heart Failure. Kristin Lewis, DVM Pathology Resident/Graduate Research Associate The Ohio State University, Columbus, OH - PowerPoint PPT PresentationTRANSCRIPT
The Myofilament Ca2+ Sensitizer Levosimendan Preserves Systolic Function in
Rats with Volume Overload Heart Failure
Kristin Lewis, DVMPathology Resident/Graduate Research Associate
The Ohio State University, Columbus, OHThe Research Institute, Nationwide Children’s Hospital, Columbus, OH
2 types of hemodynamic overload HF
© Increased afterload© Concentric hypertrophy© Fibrosis© Examples:
• Hypertension• Aortic stenosis
© Increased preload© Eccentric hypertrophy© ECM degradation© Examples:
• Aortic/Mitral regurgitation • Myocardial infarct• Ventricular septal defect• Arterio-venous fistulae
Volume OverloadPressure Overload
VolumeOverload
Progression of Volume Overload (VO) to Heart Failure
Death
Mitral regurgitation
SystolicDysfunction
DiastolicDysfunction
HF
LV Remodeling LV Dysfunction Overt HF
Time (months to years) Time (months)
Reversible Irreversible
Arterio-venous Fistulae
MR treatment options
• Surgical repair/replacement– Optimal timing for patients with symptoms or decreased
function is defined– Optimal timing for asymptomatic patients is controversial
• Intervene early or “watch and wait”?– Post-operative dysfunction
• Pharmacologic therapy– Can these agents delay surgery or improve function post-
operatively?– Optimal agents?
VO-induced HF with aortocaval fistula (ACF) in the rat
Aorta
18g
Sham 4 wk ACF
ACF progressive increase in LVEDd, LVEDs
LVEDd LVEDs
15 wk ACF8 wk ACF
Chest wall“Anterior”
“Posterior”
Time
VO is accompanied by functional deterioration
Sham ACF0
10
20
30
40
50% Fractional Shortening
*
0 200 400 6000
50
100
150
Volume (l)
Pres
sure
(mm
Hg)
*
*= P < 0.05 vs. ShamLVEDd LVEDs % 𝐹𝑆=100 𝑥 𝐿𝑉𝐸𝐷𝑑−𝐿𝑉𝐸𝐷𝑠𝐿𝑉𝐸𝐷𝑑
-6.0 -5.5 -5.0 -4.5 -4.00
20
40
60
80
100
pCa
Forc
e (m
N/m
m2 )
Sham
ACF
*
ACF Altered Ca2+ responsiveness and handling8 wk ACF
PLB
pPLB
SERCA2a
Sham ACF
8 wk ACF
*** p<0.001 vs. Sham
Arb
itrar
y U
nits
Serca 2a pPLB/PLB0
1
2
3 ShamACF
***
Hypothesis
Therapeutic strategies targeting myofilament Ca2+ sensitivity will preserve/improve LV
function in valvular heart disease
Myofilament Ca2+ sensitizer: Levosimendan
HemodymanicsMyocyte isolationTissue collection
(n=28)
(n=22)ACF
SHAM
ACF (n=23)
0 wk 8 wk
ECHO(q2w)
Levo, 1 mg/kg
Adapted from Papp Z, et al. Int J Cardiol. 2011 Jul 23.
Levo may attenuate the increase in LVEDD
LVEDd LVEDs
Sham ACF-Veh ACF-Levo
**** p<0.0001 vs Sham-Veh; ^ p<0.05, ^^ p<0.01 vs ACF-Veh
LVEDD
0 2 4 6 86
8
10
12
Study Week
(mm
) ****,̂ ^
********
****
********
****,^
Sham-VehACF-VehACF-Levo
Levo improved LV systolic function
* p<0.05, ** p<0.01, *** p<0.001, **** p<0.0001 vs Sham-Veh^ p<0.05, ^^^^ p<0.0001 vs ACF-Veh
Fractional Shortening
0 2 4 6 825
30
35
40
45
50
Study week
%
**** ****
^̂ ^̂ ^̂ ^̂***
ACF-LevoACF-VehSham-Veh
Ees, Adj
mm
Hg/
uL
Sham-Veh ACF-Veh ACF-Levo0.0
0.2
0.4
0.6
0.8
1.0
***
*,̂
PRSW, Adj
mm
Hg
Sham-Veh ACF-Veh ACF-Levo0
50
100
150
*
^
Levo ↑myofilament Ca2+ sensitivity & ↑ maximal force without ↑ Ca2+ transient
-6.0 -5.5 -5.0 -4.5 -4.00
20
40
60
80
100
120
pCa
Forc
e (m
N/m
m2 )
ShamACF-VehACF-Levo
**
^̂ ^
* p<0.05, ** p<0.01 vs Sham-Veh^ p<0.05, ^^^ p<0.001, ^^^^ p<0.0001 vs ACF-Veh
Peak[Ca2+]i
360
/380
Sham-Veh ACF-Veh ACF-Levo0
10
20
30*
^̂ ^̂
AS/PK
m*m
sec/
m
Sham-Veh ACF-Veh ACF-Levo0
20
40
60
*,̂
Peah h
t0
ACF-Veh
Sham-Veh
ACF-Levo
AreaC
Levo does not result in vasodilation
Mean arterial pressurePr
essu
re (
mm
Hg)
Sham-Veh ACF-Veh ACF-Levo0
50
100
150
Levo improved LV diastolic function
**** p<0.0001 vs Sham-Veh^ p<0.05, ^^^ p<0.001 vs ACF-Veh
Relaxation constantTau (W)
Sham-Veh ACF-Veh ACF-Levo0
5
10
15
mSe
c
^
dp/dtmin
Sham-Veh ACF-Veh ACF-Levo-10000
-8000
-6000
-4000
-2000
0
mm
Hg/s
ec****
^̂ ^
cMyBP-C and cTnI• Cardiac Myosin Binding
Protein-C (cMyBP-C)– Thick filament associated
protein– Phosphorylation ↑
contraction and relaxation & ↓Ca2+ sensitivity
• Cardiac Troponin I (cTnI)– Thin filament associated protein– Phosphorylation ↓Ca2+
sensitivity earlier onset of relaxation
Adapted from Landstrom AP, et al. Circulation. 2010 Dec 7;122(23):2441-9Colson BA et al. J Mol Cell Cardiol. 2012 Nov; 53(5):609-16Michalek AJ et al. Biophys J. 2013 Jan 22;104(2):442-52.
Phosphorylation at cMyBP-C Ser273, Ser302 and cTnI Ser23/24 may drive functional improvement
pSer273
Total cMyBP-C
Sham ACF ACF+L Sham ACF ACF+L
pSer302
Total cMyBP-C
Sham ACF ACF+L
pSer23/24
Total cTnI
cMyBP-C Ser273 Phosphoryation
Sham ACF-Veh ACF-Levo0.0
0.5
1.0
1.5
2.0
2.5
pSer
273/
tota
l
*,̂ ^
cMyBP-C Ser302 Phosphorylation
Sham ACF-Veh ACF-Levo0
1
2
3
4
5
pSer
302/
tota
l
*,̂
cTnI Ser23/24 Phosphorylation
Sham ACF-Veh ACF-Levo0.0
0.5
1.0
1.5
2.0
pTnI
/TnI
*,̂ ^
Summary Myofilament Ca2+ sensitizer therapy improved systolic and diastolic
function
Improved systolic function is due to increased myofilament Ca2+ sensitivity
Improved diastolic function may be due to cMyBP-C and/or cTnI phosphorylation
Myofilament Ca2+ sensitizer therapy mildly attenuated increase in LVEDD
Therapeutic strategies targeting myofilament Ca2+ sensitivity may improve function prior to load reduction surgery
AcknowledgementsNationwide Children’s Hospital• Lucchesi lab
– Pam Lucchesi– Aaron Trask– Aaron West– Jean Zhang– Anu Guggilam– Kirk Hutchinson– Mary Cismowski
• Vivarium– Natalie Snyder– Brenna Barbour– Erin Grove
The Ohio State University• Veterinary Biosciences
Funding Sources• ACVP/STP Coalition
Fellowship & Genentech• NIH R01-HL056046• Nationwide Children’s