Viral-mediated gene delivery of constitutively activated Gαs alters vasoreactivity

1. Decline in β-adrenoceptor (β-AR)-mediated function occurs with increasing age, as well as in multiple disease conditions. The mechanisms responsible for this decline include alterations in β-AR itself, β-AR coupling proteins, such as G-proteins, or other β-AR-linked proteins, such as G-protein receptor kinases and/or phosphatases. 2. The present study examines the physiological effects of in vitro transfer of constitutively activated Gαs (Gαs-Q227L) to both cultured vascular smooth muscle cells (VSMC) and whole aortic tissue of 6-month-old (adult) animals via a replication-deficient Herpes simplex virus (HSV) vector. These studies were conducted to provide a model for future examination of the role of Gαs in the age-related decline in β-AR-mediated vasorelaxation. 3. Gene transfer was confirmed by western blotting for specific proteins. Aortic tissue infected with HSV-Gαs-Q227L had reduced phenylephrine-induced contraction and enhanced isoproterenol-stimulated vasorelaxation. Infection of cultured VSMC with HSV-Gαs-Q227L increased both basal- and isoproterenol-stimulated cAMP accumulation, whereas forskolin-stimulated cAMP production was unchanged. 4. These results implicate Gαs as a target for further investigation in age-related changes in vascular reactivity and support the use of viral-mediated gene transfer as an effective tool to study adrenergic signal transduction and physiology in vascular tissue.