Relationship between inhibitory action of tanshinone on neutrophil function and its prophylactic effects on myocardial infarction

In isoprenaline-induced myocardial infarction in rabbits, the circulating neutrophils (neu) were in an activated state. tanshinone (tan, ig) suppressed the neu functions (acid-phosphatase release, adhesiveness, and phagocytosis) dose-dependently and reduced myocardial necrosis concomitantly. There was a positive correlation between neu functions and myocardial necrosis. In addition, tan caused an obvious decrease in content of lipoperoxide malondialdehyde in serum and myocardium, an increase in superoxide dismutase activity, an inhibition of leukocytic infiltration, and a production of prostaglandin E2 in myocardium. These effects were also related closely to the suppression of neu functions. Anti-inflammatory drug dexamethasone was used as control and had similar effects on Neu functions and myocardial infarction. It is suggested that the prophylactic effects of tan on myocardial infarction may result from the inhibition of circulating neu functions.