Revascularization in the rabbit hindlimb: dissociation between capillary sprouting and arteriogenesis.
OBJECTIVE
Animal models of hindlimb ischemia are critical to our understanding of peripheral vascular disease and allow us to evaluate therapeutic strategies aimed to improve peripheral collateral circulation. To further elucidate the processes involved in revascularization following ischemia, we evaluated the temporal association between tissue ischemia, vascular endothelial cell growth factor (VEGF) release, angiogenesis (capillary sprouting), arteriogenesis (growth of the larger muscular arteries), and reserve blood flow (functional collateral flow).


METHODS
New Zealand White rabbits (male 3-4 kg) were evaluated at specific days (0, 5, 10, 20 or 40) following femoral artery removal for measurement of hindlimb blood flow, skeletal muscle lactate production and VEGF content, capillary density (a marker of angiogenesis), and angiographic score (a marker of arteriogenesis).


RESULTS
Maximal capillary sprouting occurred within 5 days of femoral artery removal and was temporally associated with reduced resting hindlimb blood flow, increased lactate release and detectable levels of skeletal muscle VEGF. The growth of larger angiographically visible collateral vessels occurred after 10 days and was not temporally associated with ischemia or skeletal muscle VEGF content, but did coincide with a large functional improvement in the reserve blood flow capacity of the limb.


CONCLUSIONS
Following femoral artery removal in the rabbit, the time course of angiogenesis and arteriogenesis were clearly distinct. Tissue ischemia and/or VEGF may stimulate capillary sprouting, but this response does not translate to a significant improvement in collateral flow. The growth and development of the larger collateral vessels was correlated with a large functional improvement in collateral flow, and occurred at a time when VEGF levels were undetectable.
Hershey
J C
JC
Department of Pharmacology, Merck Research Laboratories, Merck and Co. Inc., WP46-200, West Point, PA 19486, USA.
Baskin
E P
EP
Glass
J D
JD
Hartman
H A
HA
Gilberto
D B
DB
Rogers
I T
IT
Cook
J J
JJ
D000704:Analysis of Variance; D000818:Animals; D001158:Arteries; D002196:Capillaries; D003097:Collateral Circulation; D016228:Endothelial Growth Factors / Q000378:metabolism; D006614:Hindlimb / Q000098:blood supply* / Q000000981:diagnostic imaging; D007083:Iliac Artery / Q000503:physiopathology; D007511:Ischemia / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology*; D019344:Lactic Acid / Q000378:metabolism; D008222:Lymphokines / Q000378:metabolism; D008297:Male; D018919:Neovascularization, Physiologic; D016491:Peripheral Vascular Diseases / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology*; D011817:Rabbits; D011859:Radiography; D013997:Time Factors; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D016228:Endothelial Growth Factors; D008222:Lymphokines; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D019344:Lactic Acid