Reversal of chronic molecular and cellular abnormalities due to heart failure by passive mechanical ventricular containment.
Passive mechanical containment of failing left ventricle (LV) with the Acorn Cardiac Support Device (CSD) was shown to prevent progressive LV dilation in dogs with heart failure (HF) and increase ejection fraction. To examine possible mechanisms for improved LV function with the CSD, we examined the effect of CSD therapy on the expression of cardiac stretch response proteins, myocyte hypertrophy, sarcoplasmic reticulum Ca2+-ATPase activity and uptake, and mRNA gene expression for myosin heavy chain (MHC) isoforms. HF was produced in 12 dogs by intracoronary microembolization. Six dogs were implanted with the CSD and 6 served as concurrent controls. LV tissue from 6 normal dogs was used for comparison. Compared with normal dogs, untreated HF dogs showed reduced cardiomyocyte contraction and relaxation, upregulation of stretch response proteins (p21ras, c-fos, and p38 alpha/beta mitogen-activated protein kinase), increased myocyte hypertrophy, reduced SERCA2a activity with unchanged affinity for calcium, reduced proportion of mRNA gene expression for alpha-MHC, and increased proportion of beta-MHC. Therapy with the CSD was associated with improved cardiomyocyte contraction and relaxation, downregulation of stretch response proteins, attenuation of cardiomyocyte hypertrophy, increased affinity of the pump for calcium, and restoration of alpha- and beta-MHC isoforms ratio. The results suggest that preventing LV dilation and stretch with the CSD promotes downregulation of stretch response proteins, attenuates myocyte hypertrophy and improves SR calcium cycling. These data offer possible mechanisms for improvement of LV function after CSD therapy.
Sabbah
Hani N
HN
Department of Medicine, Division of Cardiovascular Medicine, Henry Ford Heart and Vascular Institute, Detroit, Mich, USA. HSabbah1@hfhs.org
Sharov
Victor G
VG
Gupta
Ramesh C
RC
Mishra
Sudhish
S
Rastogi
Sharad
S
Undrovinas
Albertas I
AI
Chaudhry
Pervaiz A
PA
Todor
Anastassia
A
Mishima
Takayuki
T
Tanhehco
Elaine J
EJ
Suzuki
George
G
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D006348:Cardiac Surgical Procedures; D006332:Cardiomegaly / Q000378:metabolism / Q000517:prevention & control; D048429:Cell Size; D002908:Chronic Disease; D004195:Disease Models, Animal; D004285:Dogs; D004558:Electric Stimulation; D006333:Heart Failure / Q000150:complications / Q000503:physiopathology* / Q000628:therapy*; D006352:Heart Ventricles / Q000503:physiopathology* / Q000601:surgery; D020007:Implants, Experimental; D008863:Microspheres; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009200:Myocardial Contraction; D032383:Myocytes, Cardiac / Q000378:metabolism / Q000473:pathology; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D013314:Stress, Mechanical; D013318:Stroke Volume; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000209:etiology; D024723:Ventricular Myosins / Q000235:genetics / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases; D000099211:Phospholamban
D002118:Calcium; D002135:Calcium-Binding Proteins; D000252:Calcium-Transporting ATPases; D020928:Mitogen-Activated Protein Kinases; D016760:Proto-Oncogene Proteins c-fos; D016283:Proto-Oncogene Proteins p21(ras); D012333:RNA, Messenger; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D024723:Ventricular Myosins; D048051:p38 Mitogen-Activated Protein Kinases; D000099211:Phospholamban