Modification of myosin gene expression by imidapril in failing heart due to myocardial infarction.
The beneficial effects of imidapril, an angiotensin converting enzyme (ACE) inhibitor were investigated on changes in myofibrillar ATPase as well as myosin heavy chain (MHC) content and gene expression due to myocardial infarction (MI). Three weeks after occluding the left coronary artery, rats were treated with or without imidapril (1 mg/kg/day), for 4 weeks. The infarcted hearts exhibited depressed rates of left ventricular (LV) pressure development (57+/-2.4% reduction) and pressure decay (55.5+/-1.6% reduction). LV myofibrillar Ca(2+) ATPase activity, unlike that in the right ventricle (RV), was decreased in the infarcted animals compared with controls (6.8+/-0.4 vs 10.3+/-0.6 micromol Pi/mg/hr). MHC alpha-isoform contents were decreased by 47 and 41% whereas those of MHC beta-isoform were increased by 823 and 1200% in the LV and RV due to MI, respectively. MHC alpha-isoform mRNA levels were decreased by 55 and 35% whereas those for MHC beta-isoform were increased by 50 and 30% in the infarcted LV and RV, respectively. Imidapril treatment partially prevented the changes due to MI in LV function (rate of pressure development, 24+/-2.3% reduction and rate of pressure decay, 14+/-1.8% reduction), myofibrillar Ca(2+) ATPase activity (8.2+/-0.7 micromol Pi/mg/hr), MHC protein content (alpha-MHC, 24% reduction and beta-MHC, 525% increase) and MHC gene expression (alpha-MHC, 18% reduction and beta-MHC, 15% increase). The results suggest that the beneficial effects of ACE inhibition on the failing heart are associated with improvements in myofibrillar ATPase activities as well as prevention of changes in MHC isozyme protein contents and their gene expression.
Wang
Jingwei
J
Institute of Cardiovascular Sciences, St Boniface General Hospital Research Centre, & Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada.
Liu
Xueliang
X
Ren
Bin
B
Rupp
Heinz
H
Takeda
Nobuakira
N
Dhalla
Naranjan S
NS
D000251:Adenosine Triphosphatases / Q000187:drug effects / Q000378:metabolism; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D000818:Animals; D005786:Gene Expression Regulation / Q000187:drug effects*; D007093:Imidazoles / Q000494:pharmacology* / Q000627:therapeutic use; D048289:Imidazolidines; D008297:Male; D009203:Myocardial Infarction / Q000188:drug therapy* / Q000235:genetics* / Q000378:metabolism; D009210:Myofibrils / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D009218:Myosins / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D020033:Protein Isoforms / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
D000806:Angiotensin-Converting Enzyme Inhibitors; D007093:Imidazoles; D048289:Imidazolidines; D020033:Protein Isoforms; D012333:RNA, Messenger; C065166:imidapril; D000251:Adenosine Triphosphatases; D009218:Myosins