Angiostatin inhibits coronary angiogenesis during impaired production of nitric oxide.
BACKGROUND
The in vivo mechanism by which inhibition of NO synthase impairs ischemia-induced coronary vascular growth is unknown. We hypothesized that production of the growth inhibitor angiostatin increases during decreased NO production, blunting angiogenesis and collateral growth.


RESULTS
Measurements were made in myocardial tissue or interstitial fluid (MIF) from dogs undergoing repetitive coronary occlusions under control conditions or during antagonism of NO synthase (N(G)-nitro-L-arginine methyl ester [L-NAME]) for 7, 14, or 21 days. A sham group was instrumented identically but received no occlusions. In controls, capillary density in the ischemic zone increased initially but returned to baseline at the later times. In the L-NAME group, capillary density was lower at 7 days compared with that of controls. MIF from control dogs induced in vitro endothelial tube formation and cell proliferation, significantly greater than that from the L-NAME group. MIF from shams did not stimulate tube formation. In controls or shams, tube formation or cell proliferation did not change after administration of antiangiostatin, but this antibody restored the responses to control levels in the L-NAME group. Angiostatin expression in MIF was increased in the L-NAME group compared with controls and shams. The activities of tissue matrix metalloproteinases (MMPs) MMP-2 and MMP-9, which generate angiostatin, were increased in the L-NAME group.


CONCLUSIONS
Inhibition of NO synthase increased expression of angiostatin and activities of MMP-2 and MMP-9. Our findings indicate that angiostatin inhibits coronary angiogenesis during compromised NO production and may underscore the impairment of coronary angiogenesis during endothelial dysfunction.
Matsunaga
Toshiro
T
Department of Physiology, the Cardiovascular Center, Medical College of Wisconsin, Milwaukee 53226, USA..
Weihrauch
Dorothee W
DW
Moniz
Melinda C
MC
Tessmer
John
J
Warltier
David C
DC
Chilian
William M
WM
D020533:Angiogenesis Inhibitors / Q000502:physiology*; D043168:Angiostatins; D000818:Animals; D002196:Capillaries / Q000254:growth & development; D002455:Cell Division; D002478:Cells, Cultured; D003097:Collateral Circulation; D003326:Coronary Circulation; D004285:Dogs; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000254:growth & development; D005110:Extracellular Space / Q000378:metabolism; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D020782:Matrix Metalloproteinases / Q000378:metabolism; D017202:Myocardial Ischemia / Q000097:blood* / Q000378:metabolism*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D018919:Neovascularization, Physiologic / Q000187:drug effects; D009569:Nitric Oxide / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D010446:Peptide Fragments / Q000502:physiology*; D010958:Plasminogen / Q000502:physiology*
D020533:Angiogenesis Inhibitors; D010446:Peptide Fragments; D009569:Nitric Oxide; D043168:Angiostatins; D010958:Plasminogen; D019001:Nitric Oxide Synthase; D020782:Matrix Metalloproteinases; D019331:NG-Nitroarginine Methyl Ester