EXPRESSION AND FUNCTION OF RECOMBINANT ENDOTHELIAL NITRIC-OXIDE SYNTHASE GENE IN CANINE BASILAR ARTERY AFTER EXPERIMENTAL SUBARACHNOID HEMORRHAGE

Background and Purpose-Gene transfer with recombinant viral vectors en coding vasodilator proteins may be useful in therapy of cerebral vasos pasm after subarachnoid hemorrhage (SAH). Relaxations mediated by nitr ic oxide are impaired in cerebral arteries affected by SAH. The presen t study was designed to determine the effect of SAH on the efficiency of ex vivo adenovirus-mediated gene transfer to canine basilar arterie s and to examine whether expression of recombinant endothelial nitric oxide synthase (eNOS) gene may have functional effects on vasomotor re activity of spastic arteries affected by SAH. Methods-Replication-defi cient recombinant adenovirus vectors encoding bovine eNOS (AdCMVeNOS) and Escherichia coli beta-galactosidase (AdCMV beta-Gal) genes were us ed for ex vivo gene transfer. Rings of basilar arteries obtained from control dogs and dogs exposed to SAH were incubated with the vectors i n minimum essential medium. Twenty-four hours after gene transfer, exp ression and function of the recombinant genes were evaluated by (1) hi stochemical or immunohistochemical staining, (2) beta-galactosidase pr otein measurement, and (3) isometric tension recording. Results-Transd uction with AdCMV beta-Gal and AdCMVeNOS resulted in the expression of recombinant beta-galactosidase and eNOS proteins mostly in the vascul ar adventitia. The expression of beta-galactosidase protein was approx imate to 2-fold higher in SAH arteries than in normal arteries. Endoth elium-dependent relaxations caused by bradykinin and substance P were suppressed in SAH arteries. The relaxations to bradykinin were signifi cantly augmented in both normal and SAH arteries after AdCMVeNOS trans duction but not after AdCMV beta-Gal transduction. The relaxations to substance P were augmented by AdCMVeNOS transduction only in normal ar teries. Bradykinin and substance P caused relaxations even in endothel ium-denuded arteries, when the vessels were transduced with AdCMVeNOS. These endothelium-independent (adventitia-dependent) relaxations to b radykinin observed after AdCMVeNOS transduction were similar between n ormal and SAH arteries, whereas those to substance P were significantl y reduced in SAH arteries compared with normal arteries. Conclusions-T hese results suggest that expression of recombinant proteins after ade novirus-mediated gene transfer may be enhanced in cerebral arteries af fected by SAH and that successful eNOS gene transfer to spastic arteri es can at least partly restore the impaired nitric oxide-mediated rela xations through local (adventitial) production of nitric oxide.