Dynamic remodeling of arteriolar collaterals after acute occlusion in chick chorioallantoic membrane.

ObjectiveAfter arteriolar occlusion, collaterals enlarge and initially elevated WSS normalizes. While most previous studies focused on endpoints of such adaptive changes in larger collaterals, the present investigation aimed to continuously determine the relation between WSS and diameter in microvascular collaterals during adaptive reactions. MethodsIn Hamburger-Hamilton stage 40 CAMs, junction points between arteriolar segments were identified and the third upstream segment on one side was occluded. Intravital microscopy recordings were taken for 24hours post-occlusion. Segment diameter and blood velocity were measured: WSS and capillary density were calculated. ResultsAfter occlusion, vascular diameters exhibited an immediate decrease, then increased with a time constant of 2.50.8hours and reached a plateau of up to 60% above baseline after about 7hours. Vascular tone showed no significant change. WSS exhibited an immediate increase post-occlusion and linearly returned to baseline after about 12hours. Local WSS change and diameter change rate showed similar patterns during the initial but not the later phase of post-occlusive adaptation. ConclusionsCAM collaterals undergo fast structural remodeling within 24hours post-occlusion. This remodeling might be driven by local WSS and by other regulators within the vascular network.