title: The calibre changes of retinal vessels subject to prolonged hyperoxia.
abstract: The constriction of retinal vessels occurring in response to breathing 100% oxygen was studied in 10 normal subjects over a period of 30 min. Brachial blood pressure, radial pulse and end tidal CO2 were recorded throughout. The mean arteriolar constriction was 15.3% +/- 4.6 and venous constriction 21.8% +/- 4.3. Time constants (the time for 95% of the maximal response to have occurred) were 2.25 min +/- 0.75 and 2.37 min +/- 0.57 for arterioles and veins respectively. A highly variable late vascular response was recorded. A small proportion of arterial vessels showing a response were nonuniform while a larger proportion of veins showed a significant dilatation.
mesh_terms: D000328:Adult; D001160:Arterioles / Q000502:physiology; D002245:Carbon Dioxide / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D010100:Oxygen / Q000494:pharmacology / Q000502:physiology*; D012171:Retinal Vessels / Q000502:physiology*; D013997:Time Factors; D014661:Vasoconstriction / Q000187:drug effects; D014699:Venules / Q000502:physiology
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen