[The effects of nicorandil on the cardiovascular system under isoflurane anesthesia]

The effects of nicorandil on the cardiovascular system were evaluated in twenty dogs with open chests, randomly divided into groups of ten each. The first group was anesthetized with isoflurane 0.75% and the second group with 1.5%. Dogs of both groups were intravenously administered with nicorandil in three levels of dosage--100, 300 and 1000 micrograms.kg-1. With 100 and 300 micrograms.kg-1, vasodilatory effects were observed dose-dependently. With 1000 micrograms.kg-1, transient suppressive effect on myocardial contraction besides vasodilatory effect was observed. At the higher concentration of isoflurane, blood pressure and heart rate decreased, whereas coronary blood flow increased for a longer period with 300 micrograms.kg-1 after the nicorandil administration. The above result suggests that under isoflurane anesthesia, nicorandil, if administered carefully, is an efficacious antianginal drug free from the danger of myocardial depression or excessive vasodilation.