Insulin-like growth factor-1 stimulates vascular smooth muscle cell proliferation in rat aorta in vivo.
IGF-I is a mitogen for vascular smooth muscle cells (SMC) in vitro and enhances SMC proliferation in vivo in diabetic rats. In this study, we examined the effect of IGF-I on SMC proliferation in vivo in normal rats. Recombinant human IGF-I (0.87 and 3.1 mg/kg/day), was infused via osmotic minipumps in normal rats starting 3 days before they were subjected to aortic injury with a balloon catheter. IGF-I at an infusion rate of 3.1 mg/kg/day caused a significant increase in 3H-thymidine incorporation into DNA (+53%, P < 0.01) in the rat aortic intima-media 2 days after injury and DNA content (+13%, P < 0.05) after 11 days. The elastin and collagen contents were not changed by IGF-I infusion after 11 days. Body weight increased slightly while blood glucose was not affected. At an infusion rate of 0.87 mg/kg/day, IGF-I had no significant effects. These results suggest that circulating levels of IGF-I can stimulate SMC proliferation in vivo in normal rats but only at high concentrations.
Chen
Y
Y
Department of Cell Biology, Faculty of Health Sciences, University of Linköping, Sweden.
Capron
L
L
Magnusson
J O
JO
Wallby
L A
LA
Arnqvist
H J
HJ
D000818:Animals; D001835:Body Weight / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D004247:DNA / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007260:Infusion Pumps; D007334:Insulin-Like Growth Factor I / Q000378:metabolism / Q000494:pharmacology*; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000187:drug effects* / Q000293:injuries; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000494:pharmacology
D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I; D004247:DNA