Structure of carotid artery in baboon and rat and differences in their response to endothelial denudation angioplasty

BACKGROUND. Most studies dealing with vascular response to injury have been conducted using rodent and rabbit models, although it is expected that the response to injury in these species is dissimilar from man. AIMS. Here we compare the structure of native carotid artery in rat and bab oon and the response of these vessels to endothelial denudation angioplasty . METHODS. in both species, the carotid is a musculoelastic artery. Only babo on carotid has a distinct intima, correlating in size with the weight of ma le baboons, Complete endothelial denudation of left carotid was performed o n eight male baboons and 24 male rats by applying an equivalent pull force with a Fogarthy catheter. The animals were sacrificed prior to and 15 min a nd 2, 3, 4, 7, 14 and 28 days postinjury, one baboon and three rats per tim e point. RESULTS. Re-endothelialization in the baboon was complete already on day 4, whereas in the rat it was still incomplete on day 28. The proliferative re sponse to injury was far smaller in the baboon than in the rat, the intimal area increased only by 5-fold in baboon compared with 25-fold in rat, and the number of intimal nuclei by 4-fold in baboon compared with 12-fold in r at. Complete compensatory remodelling of the lumen size occurred in the bab oon, whereas in the rat remodelling remained incomplete. The cell types par ticipating in the response were, however, similar: deposition of thrombocyt es on denuded luminal surface, expression of alpha -actin by intimal cells, and lack of any significant white cell infiltration in the denuded intima. CONCLUSIONS. Baboon carotids are very different from rat carotids both in t heir native structure and in their response to injury. With the limited amo unt of information available from human vessels, baboon carotids closely re semble human carotids in both respects.