Deprecated: Implicit conversion from float 227.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 227.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 227.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 227.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 227.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 227.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 227.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 261.2 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 261.2 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 261.2 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 261.2 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 294.79999999999995 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 294.79999999999995 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 294.79999999999995 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 294.79999999999995 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 294.79999999999995 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 294.79999999999995 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Warning: imagejpeg(C:\Inetpub\vhosts\kidney.de\httpdocs\phplern\28073805
.jpg): Failed to open stream: No such file or directory in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 117 Circulation
2017 ; 135
(17
): 1632-1645
Nephropedia Template TP
gab.com Text
Twit Text FOAVip
Twit Text #
English Wikipedia
Sheet-Like Remodeling of the Transverse Tubular System in Human Heart Failure
Impairs Excitation-Contraction Coupling and Functional Recovery by Mechanical
Unloading
#MMPMID28073805
Seidel T
; Navankasattusas S
; Ahmad A
; Diakos NA
; Xu WD
; Tristani-Firouzi M
; Bonios MJ
; Taleb I
; Li DY
; Selzman CH
; Drakos SG
; Sachse FB
Circulation
2017[Apr]; 135
(17
): 1632-1645
PMID28073805
show ga
BACKGROUND: Cardiac recovery in response to mechanical unloading by left
ventricular assist devices (LVADs) has been demonstrated in subgroups of patients
with chronic heart failure (HF). Hallmarks of HF are depletion and
disorganization of the transverse tubular system (t-system) in cardiomyocytes.
Here, we investigated remodeling of the t-system in human end-stage HF and its
role in cardiac recovery. METHODS: Left ventricular biopsies were obtained from 5
donors and 26 patients with chronic HF undergoing implantation of LVADs.
Three-dimensional confocal microscopy and computational image analysis were
applied to assess t-system structure, density, and distance of ryanodine receptor
clusters to the sarcolemma, including the t-system. Recovery of cardiac function
in response to mechanical unloading was assessed by echocardiography during
turndown of the LVAD. RESULTS: The majority of HF myocytes showed remarkable
t-system remodeling, particularly sheet-like invaginations of the sarcolemma.
Circularity of t-system components was decreased in HF versus controls (0.37±0.01
versus 0.46±0.02; P<0.01), and the volume/length ratio was increased in HF
(0.36±0.01 versus 0.25±0.02 µm(2); P<0.0001). T-system density was reduced in HF,
leading to increased ryanodine receptor-sarcolemma distances (0.96±0.05 versus
0.64±0.1 µm; P<0.01). Low ryanodine receptor-sarcolemma distances at the time of
LVAD implantation predicted high post-LVAD left ventricular ejection fractions
(P<0.01) and ejection fraction increases during unloading (P<0.01). Ejection
fraction in patients with pre-LVAD ryanodine receptor-sarcolemma distances >1 µm
did not improve after mechanical unloading. In addition, calcium transients were
recorded in field-stimulated isolated human cardiomyocytes and analyzed with
respect to local t-system density. Calcium release in HF myocytes was restricted
to regions proximal to the sarcolemma. Local calcium upstroke was delayed
(23.9±4.9 versus 10.3±1.7 milliseconds; P<0.05) and more asynchronous (18.1±1.5
versus 8.9±2.2 milliseconds; P<0.01) in HF cells with low t-system density versus
cells with high t-system density. CONCLUSIONS: The t-system in end-stage human HF
presents a characteristic novel phenotype consisting of sheet-like invaginations
of the sarcolemma. Our results suggest that the remodeled t-system impairs
excitation-contraction coupling and functional recovery during chronic LVAD
unloading. An intact t-system at the time of LVAD implantation may constitute a
precondition and predictor for functional cardiac recovery after mechanical
unloading.