NITROGLYCERIN DECREASES MEDIAL SMOOTH-MUSCLE CELL-PROLIFERATION AFTERARTERIAL BALLOON INJURY

Purpose: Nitroglycerin and its effector molecules nitric oxide and cyc lic guanosine monophosphate decrease smooth muscle cell proliferation in vitro. We examined the in vivo effect of nitroglycerin on intimal h yperplasia. Methods: We treated rats after carotid artery balloon inju ry with nitroglycerin delivered paraarterially with a miniosmotic pump for 1 week. Results: High nitroglycerin serum levels were achieved, a nd the level of cyclic guanosine monophosphate in the carotid artery w all was significantly increased (1.48 +/- 0.37 vs 0.86 +/- 0.39 pmol/m g protein; p < 0.05) in the nitroglycerin-treated group. Cellular prol iferation in the arterial wall was assessed by incorporation of 5-brom o-2'-deoxyuridine 6 days after the injury and was lower in the nitrogl ycerin-treated group (15.2 +/- 3.4 vs 36.3 +/- 5.5 positive cells/sect ion; p < 0.005). This was due to a decrease in the number of prolifera ting cells in the media (6.3 +/- 1.2 vs 21.8 +/- 4.5; p < 0.005), wher eas in the budding neointima, the difference in the number of prolifer ating cells was not significant. Neointimal lesions 21 days after the injury did not differ in cross-sectional intimal area, in intimal/medi al area ratio, and in cell density. Conclusion: Nitroglycerin decrease d medial cellular proliferation after balloon injury and had no signif icant effect on intimal proliferation. The size of the neointimal lesi on was not affected by nitroglycerin therapy.