HETEROGENEOUS EXPRESSION OF ANGIOTENSIN-II AT(1) RECEPTORS IN NEOINTIMA OF RAT CAROTID-ARTERY AND AORTA AFTER BALLOON CATHETER INJURY

We examined the expression of angiotensin II receptor subtypes and angiotensin-converting enzyme in the rat aorta and carotid artery at 1, 2, 4, 8, 15, and 30 days after balloon catheter injury or sham surgery. The AT(1) receptor expression was enhanced in the neointima at 8 days in the aorta and carotid artery compared to that in intact media. Maintenance of the high expression of AT(1) receptors in the neointimal tissue at 15 and 30 days was localized to a subpopulation of neointimal cells close to the lumen of the vessel and was correlated to the distribution of smooth muscle cells immunoreactive to proliferating cell nuclear antigen. During the initial stages after injury, binding of [I-125]351A to angiotensin-converting enzyme was significantly decreased in both the intima/media layers as well as adventitia in carotid artery and aorta. Binding of [I-125]351A to angiotensin-converting enzyme was significantly lower in the neointima compared to that in the intima/media of intact vessels. Our results reveal that the expression of AT(1) receptors is heterogeneous in the neointima, and suggest that enhanced expression of AT(1) receptors in the balloon catheter-injured carotid artery and aorta may be limited to proliferating intimal smooth muscle cells.