Key Points
- To determine whether short-term macromolecule uptake and wall penetration mechanisms explain age-dependent shifts in albumin accumulation around aortic branch ostia.
- Fluorescently labeled albumin was injected into the circulation of conscious New Zealand White rabbits aged 45 days, 75 days, and adulthood.
- Thoracic aortas were fixed in situ 10 minutes post-injection and cross-sectioned through the center of intercostal ostia.
- Tracer concentrations across the intimal-medial wall were quantified using digital imaging fluorescence microscopy after autofluorescence subtraction.
- In 45-day-old rabbits, tracer uptake was higher downstream than upstream of branch ostia, with inter-regional differences exceeding 100% of the mean value.
- By 75 days, the downstream-versus-upstream uptake disparity was halved and mean tracer uptake decreased nearly threefold, persisting at this overall level into maturity.
- In mature rabbits, the spatial uptake distribution reversed, showing 22% greater tracer accumulation upstream than downstream of ostia.
Structured PICO
PPopulationConscious New Zealand White rabbits at different ages (45 days, 75 days, and mature)
IInterventionFluorescent dye-labeled albumin introduced into the circulation
OOutcomeShort-term (10 minutes) uptake of albumin and its distribution across the aortic wall near intercostal branch ostiasurrogate
Age-related changes in the pattern of albumin uptake by the aortic wall parallel those seen at quasi-steady state, suggesting they are determined by changes in wall resistance to macromolecule influx.