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 ang iotensin-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. Mai ntenance of the high expression of AT(1) receptors in the neointimal t issue 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 dist ribution of smooth muscle cells immunoreactive to proliferating cell n uclear 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 arter y and aorta. Binding of [I-125]351A to angiotensin-converting enzyme w as 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 enha nced expression of AT(1) receptors in the balloon catheter-injured car otid artery and aorta may be limited to proliferating intimal smooth m uscle cells.