ISRADIPINE INHIBITS MITOTIC AND PROLIFERATIVE ACTIVITY IN THE ARTERIAL NAIL

The anti-mitotic (H-3-thymidine uptake quantified using autoradiograph y) and anti-proliferative (counting of activated smooth muscle cells o n semithin sections) effects of the dihydropyridine calcium channel bl ocker isradipine (0.3 mg/kg) have been assessed in a rabbit arterial s tress model. Isradipine caused a significant drop in both mitotic and proliferative activity. These effects were more pronounced by pretreat ment (6 hours before lesion induction with desoxycorticosterone) with isradipine as compared to posttreatment (6 hours after experimental le sioning). The benefit induced by isradipine was abolished by aspirin t reatment. In-vitro vascular prostacyclin formation and cholesterol con tent were not affected. These findings suggest that the anti-atheroscl erotic action of isradipine on mitotic activity and cellular prolifera tion is mediated by a cyclooxygenase product, most likely via enhanced local vascular PGI(2)-synthesis.