Endovascular irradiation impairs vascular functional responses in noninjured pig coronary arteries.
OBJECTIVE
To assess the effects of endovascular irradiation on vascular structure and function in pig coronary arteries in the absence of vascular injury.


METHODS
Vasomotor responses to contractions of KCl and prostaglandin F2alpha (PGF2alpha), relaxations to endothelium-dependent (substance P, A23187) and -independent (sodium nitroprusside, SNP) agents; endothelial morphology and superoxide anion (02*-) production were investigated in control (naive), sham and irradiated (20 Gy, 32P) arteries 1 month after irradiation.


RESULTS
Contractions to KCl and PGF2alpha in the presence of L-NAME were significantly decreased, relaxations to substance P and A23187 were abolished and SNP-induced relaxation was potentiated in irradiated arteries compared to naive and sham-treated vessels. Scanning electron microscopy (SEM) revealed enlarged endothelial cells (ECs) exhibiting surface microvilli. O2*- production was significantly increased in irradiated vessels (437.0 +/- 37.3 vs. 126.0 +/- 11.6 RLU/s/mg tissue, P < .01).


CONCLUSIONS
One month after brachytherapy, normal pig coronary arteries showed abnormal vascular reactivity, altered endothelial morphology and increased production of O2*-. Lack of relaxation to substance P and A23187 reflects ionizing radiation-mediated damage to ECs, whereas potentiation of relaxation to SNP suggests additional deleterious effects on medial smooth muscle cells (SMCs). Increased O2*- production might have contributed to endothelial dysfunction by scavenging nitric oxide (NO).
Li
Jinsheng
J
American Cardiovascular Research Institute, 3155 Northwoods Place, Norcross, GA 30071, USA. jli@acrionline.org
De Leon
Hector
H
Ebato
Bunken
B
Cui
Jianhua
J
Todd
John
J
Chronos
Nicolas A F
NA
Robinson
Keith A
KA
D017130:Angioplasty / Q000009:adverse effects*; D000818:Animals; D001610:Beta Particles / Q000009:adverse effects*; D003331:Coronary Vessels / Q000473:pathology / Q000503:physiopathology* / Q000528:radiation effects*; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000473:pathology / Q000503:physiopathology / Q000528:radiation effects; D005260:Female; D005263:Femoral Artery / Q000473:pathology / Q000503:physiopathology* / Q000528:radiation effects*; D007537:Isometric Contraction / Q000502:physiology / Q000528:radiation effects; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000473:pathology / Q000503:physiopathology / Q000528:radiation effects; D013556:Swine, Miniature; D013997:Time Factors; D014666:Vasomotor System / Q000473:pathology / Q000503:physiopathology* / Q000528:radiation effects*