ENHANCED ENDOTHELIUM-DEPENDENT RELAXATIONS AFTER GENE-TRANSFER OF RECOMBINANT ENDOTHELIAL NITRIC-OXIDE SYNTHASE TO RABBIT CAROTID ARTERIES

We tested the effects of overexpression of the endothelial nitric oxid e synthase (eNOS) gene in the normal arterial wall by adenoviral-media ted gene transfer. Rabbit carotid arteries were surgically isolated an d exposed to adenoviral vectors encoding eNOS (AdeNOS) or beta-galacto sidase (Ad beta Gal) on the contralateral side. Vector solutions at a concentration of 1 x 10(10) plaque forming units/mL were instilled for 20 minutes before restoration of Bow. Arteries were harvested 4 days later for immunostaining, measurement of cGMP, and vasomotor studies. Endothelium-specific gene transfer was confirmed by staining for beta- galactosidase in the Ad beta Gal arteries, Immunostaining of en face e ndothelial cell imprints from AdeNOS-transduced arteries with a monocl onal antibody to eNOS showed increased immunoreactivity. Basal cGMP le vels were significantly greater in the AdeNOS-transduced arteries (18. 4+/-4.6 versus 4.2+/-0.5 pmol/mg protein; P<.05). Contractions to phen ylephrine were significantly reduced in the AdeNOS-transduced arteries (area under curve, 106+/-5 versus 119+/-7; P<.05), but in the presenc e of the eNOS inhibitor. N-G-monomethyl-L-arginine (L-NMMA, 3x10(-4) m ol/L), there was no difference between the two (area under curve, 148/-5 versus 153+/-6; P=NS). Relaxations to acetylcholine obtained durin g submaximal contractions to phenylephrine were significantly enhanced in the AdeNOS-transduced arteries (EC50, 7.45+/-0.05 versus 7.23+/-0. 03; P<.05). We conclude that overexpression of eNOS in the endothelium results in diminished contractile responses, as well as enhanced endo thelium-dependent relaxations. These findings imply a possible role fo r vascular eNOS gene transfer in the treatment of vasospasm and endoth elial dysfunction.