{"id":"21656201-c0d8-5047-97b0-ee80b9a5b2d2","stable_key":"488ea171-36b8-5ef6-b5d3-98563980fdbf:hbot-cbf-reduction","predicate":"reduces","statement":"After 30 minutes at 5 ATA, regional cerebral blood flow fell by 23 to 37% in substantia nigra, caudate putamen, hippocampus and parietal cortex.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"negative","is_public":true,"mechanism_event_id":"427165b2-4213-5cb4-a08a-d893d1e76d57","mechanism_event_label":"Breathing oxygen under pressure narrows brain vessels rather than flooding them.","subject":{"id":"581fa746-cb84-571b-87a0-4d461263f660","slug":"hyperbaric-oxygen","display_name":"Hyperbaric oxygen therapy","entity_type_key":"drug"},"object":{"id":"989f2859-fa97-58ec-878c-4d8a37a81bf7","slug":"regional-cerebral-blood-flow","display_name":"Regional cerebral blood flow","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"427165b2-4213-5cb4-a08a-d893d1e76d57","stable_key":"488ea171-36b8-5ef6-b5d3-98563980fdbf:hbot-cbf-reduction-event","event_type":"biochemical_relationship","label":"Breathing oxygen under pressure narrows brain vessels rather than flooding them.","description":"After 30 minutes at 5 ATA, regional cerebral blood flow fell by 23 to 37% in substantia nigra, caudate putamen, hippocampus and parietal cortex.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"581fa746-cb84-571b-87a0-4d461263f660","slug":"hyperbaric-oxygen","display_name":"Hyperbaric oxygen therapy","entity_type_key":"drug"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"989f2859-fa97-58ec-878c-4d8a37a81bf7","slug":"regional-cerebral-blood-flow","display_name":"Regional cerebral blood flow","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""}]},"contexts":[{"dimension":"evidence_span","value_text":"{\"source_cache\": \"artifacts/hbot-research/11139368.abstract.txt\", \"locator\": \"Indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"9823a7f177483257b812d7c8c8e8052c3f04d6a7aa052876369c7c64b55668f3\", \"start_char\": 0, \"end_char\": 1672, \"text_sha256\": \"9823a7f177483257b812d7c8c8e8052c3f04d6a7aa052876369c7c64b55668f3\"}","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Regional cerebral blood flow measurement in rats with nitric oxide metabolite and hydroxyl radical assays","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Oxygen at 5 atmospheres absolute for 30 minutes, with L-NAME, a nitric oxide donor, or intravascular superoxide dismutase","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Five atmospheres is well above therapeutic pressure and was chosen to study oxygen toxicity. The superoxide dismutase rescue is the key mechanistic step.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Hyperbaric oxygen research collection; topical membership is not evidence of a direct clinical effect, and a therapeutic exposure is not a dietary intake.","comparator":null,"unit":null,"notes":"","entity":{"slug":"hyperbaric-oxygen","display_name":"Hyperbaric oxygen therapy","entity_type_key":"drug"}},{"dimension":"organism","value_text":"Rat","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Breathing oxygen under pressure narrows brain vessels rather than flooding them.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[hbot-p11139368] Hyperbaric oxygen reduces cerebral blood flow by inactivating nitric oxide. 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The superoxide dismutase rescue is the key mechanistic step.\nexposure: Oxygen at 5 atmospheres absolute for 30 minutes, with L-NAME, a nitric oxide donor, or intravascular superoxide dismutase\nevidence_span: {\"source_cache\": \"artifacts/hbot-research/11139368.abstract.txt\", \"locator\": \"Indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"9823a7f177483257b812d7c8c8e8052c3f04d6a7aa052876369c7c64b55668f3\", \"start_char\": 0, \"end_char\": 1672, \"text_sha256\": \"9823a7f177483257b812d7c8c8e8052c3f04d6a7aa052876369c7c64b55668f3\"}\n[hbot-p11139368] Hyperbaric oxygen reduces cerebral blood flow by inactivating nitric oxide. 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