The aim was to investigate the direct effects of fluid shear stress on NO production by hASMC. hASMC were subjected to physiological levels of shear stress using a parallel plate flow chamber and nitrite concentration from the conditioned media was measured as an index of NO production with fluorometric assays. Flow exposure caused a biphasic production of NO, with an initial burst of NO production followed by a lower but sustained elevated NO release. Neither the rapid nor the sustained NO release was dependent on the level of shear stress in the range of 5-25 dyn/cm2. Stopping flow for 30 minutes and then restarting resulted in a rapid NO release similar to the initial burst. Experiments with Ca++ antagonists provided evidence that NO production was Ca++ dependent. Treatment with an inhibitor for nitric oxide synthase (NOS) isoforms, prevented flow induced NO production. Dexamethasone and cycloheximide, which inhibit NOS II formation were without effect on NO production. Antibodies against NOS II showed no immunoreactivity in Western blot analysis, while monoclonal antibodies against NOS I gave specific products in both control and flow cultures. Our results indicate that hASMC express a NOS I isoform whose activity is strongly modulated by flow.
|Original language||English (US)|
|State||Published - Dec 1 1997|
ASJC Scopus subject areas
- Molecular Biology