Objective: To investigate the effect of hyrerbaric oxygen(HBO) on functions of brain microvessels via nitric oxide. Method: During the experiment, the changes on pia mater microvessels of gerbils and vascular endothelial cell and smooth muscle cell of SD rats were observed by using Laser Doppler and microfluorimetry. Results: (1) The pial microarteries contracted after exposure to HBO. The pial cappillaries closed after i.p. L NAME, then opened when exposed to HBO. Dropping L NAME onto the brain surface, the pial microveins convulsed in segmental state, then recovered from the convulsion after HBO exposure. (2) During HBO exposure, the endothelial cell [Ca 2+ ] i increased and meanwhile the smooth muscle cell [Ca 2+ ] i decreased. Both sorts of cells [Ca 2+ ] i rised with L NAME treatment and then exposed to HBO, the endothelial cell [Ca 2+ ] i decreased while the smooth muscle cell [Ca 2+ ] i was maintained at a higher level. Conclusions: NO takes part in HBO mediated functions of brain mucrovessels.
