ADENOVIRAL-MEDIATED TRANSFER OF THE HUMAN ENDOTHELIAL NITRIC-OXIDE SYNTHASE GENE REDUCES ACUTE HYPOXIC PULMONARY VASOCONSTRICTION IN RATS

Nitric oxide (NO), a vasodilator involved in the regulation of pulmona ry vascular tone, is synthesized by a family of enzymes, nitric oxide synthases (NOS). To investigate whether adenoviral-mediated overexpres sion of constitutive endothelial NOS (ceNOS) would attenuate hypoxic p ulmonary vasoconstriction, we aerosolized 3 x 10(9) plaque forming uni ts of a recombinant adenovirus containing the ceNOS gene (AdCMVceNOS) into rat lungs. Four days after infection, transgene expression was co nfirmed using immunoblot techniques. Diffuse ceNOS immunostaining was detected in alveoli and medium-sized and small pulmonary vessels of Ad CMVceNOS-transduced lungs. AdCMVceNOS-transduction was associated with an 86% increase in [H-3]arginine to [H-3]citrulline conversion and a rise in pulmonary cGMP levels from 7+/-1 to 59+/-9 pmol/mg protein in lungs from AdCMVceNOS versus control rats, (P < 0.05). During acute hy poxia (FIO2 = 0.10) for 25 min, mean pulmonary artery pressure (PAP) i ncreased significantly from 17+/-1 to 27+/-1 mmHg in rats aerosolized with saline (n = 4) and from 18+1 to 28+/-1 mmHg in rats given an aden oviral vector expressing a nuclear-targeted beta-galactosidase gene (A dCMV beta gal, n = 8). In contrast, in AdCMVceNOS-transduced rats (n = 8) the hypoxia-induced increase in PAP was significantly attenuated ( 18+/-1 to 23+/-2 mmHg). Systemic blood pressure was not affected by ae rosol gene transfer. Thus, adenoviral-mediated ceNOS gene transfer to rat lungs increases ceNOS expression and activity, and reduces acute h ypoxic pulmonary vasoconstriction. Aerosolized recombinant adenovirus overexpressing vasodilatory proteins can act as a selective pulmonary vasodilator and may hold promise as a future therapeutic strategy for pulmonary hypertension.