In order to characterize in vivo shear stress-mediated vascular growth, adjacent rat mesenteric ileal and second-order arterial branches were ligated to induce blood flow increases through the immediately adjacent ileal artery. At one, three, and seven days animals were sacrificed and the mesenteric vasculature was perfusion-fixed and paraffin-embedded. Arterial cross-sections were cut and stained with toluidine blue for morphological assessment, and immunocytochemistry (ICC) was performed for proliferating cell nuclear antigen to measure DNA replication. Results indicate that, while arterial pressures were not altered by the ligation, ileal artery blood flow and shear stress were increased approximately 200% initially after ligation. In arteries with elevated flow, mean lumen diameter and wall area increased significantly compared to same animal control vessels: ileal artery at seven days (255 ± 12 vs. 287 ± 12 μm; 11394 ± 1137 vs. 18016 ± 2648 um2, respectively), and second-order artery at three (188 ± 8 vs. 215 ± 9 μm; 7263 ± 591 vs. 11073 ± 1254 μm2, respectively) and seven (201 ± 22 vs. 277 ± 23 μm; 5883 ± 676 vs. 12936 ± 1684 μm2, respectively) days. ICC data suggest an initial medial hypertrophy in the larger vessel followed by medial hyperplasia, while the smaller vessel initially exhibits medial hyperplasia with subsequent medial cellular hypertrophy These data suggest that flowmediated vascular growth occurs through a combination of cellular hypertrophy and hyperplasia and is dependent on the order of the mesenteric arterial branch.
|Original language||English (US)|
|State||Published - Dec 1 1996|
ASJC Scopus subject areas
- Molecular Biology