Is insulin-like growth factor gene expression modulated during cardiac hypertrophy?
The goal of this study was to examine the relationship between work-induced cardiac hypertrophy and insulin-like growth factor-I and -II (IGF-I and -II) mRNA expression in adult female Sprague-Dawley rats. Increased cardiac work was induced by coarctation, which involved placing a constricting silk ligature around the abdominal aorta to increase peripheral resistance. Cardiac hypertrophy was determined by measuring in vivo left ventricular protein synthesis rates. There was a rapid increase in left ventricular weight (LV) [both absolute and relative to body weight (mg tissue.100 g-1 body weight)] following the coarctation surgery. By the third day following coarctation, LV weight was increased approximately 20% and reached 24% by the 10th day as compared with controls. Protein synthesis rates increased dramatically, reached a peak level at 3 d (133%.d-1) compared with 29% Ks.d-1 in the sham operated group and then began to slowly decrease toward control rates. The fractional synthesis rates of total protein in the LV were unchanged 1 d post-surgery. IGF-I mRNA content in the LV decreased to approximately 38% below the control content at day 1. However, by 3 d post-surgery IGF-I mRNA content increased to 30-50% above controls, were 31% above control by day 7, and remained elevated thereafter. On the other hand, IGF-II mRNA content remained constant throughout the 10 d post-surgery. Work-necessitated increase in cardiac protein mass may be mediated, in part, by a local autocrine/paracrine production of IGF-I.
Czerwinski
S M
SM
Department of Animal Sciences, University of Illinois, Urbana 61801.
Novakofski
J
J
Bechtel
P J
PJ
D000818:Animals; D006332:Cardiomegaly / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D005260:Female; D005786:Gene Expression Regulation; D006352:Heart Ventricles / Q000378:metabolism / Q000473:pathology; D007334:Insulin-Like Growth Factor I / Q000235:genetics*; D007335:Insulin-Like Growth Factor II / Q000235:genetics*; D009929:Organ Size; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley
D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II