The elucidation of epinephrine as an antihypotensive agent in abamectin intoxication.

Abamectin (ABM) has been used in some suicidal attempt cases in recent years. ABM-intoxicated patients demonstrate low mean arterial pressure (MAP) and commonly treated with catecholamine to burst MAPs in their intensive cares. This investigation examined roles of epinephrine on MAP, heart rate (HR), and therein baroreflex sensitivity (BRS = HR/MAP) during ABM intoxication in rats. Oral application of ABM (20 mg/kg) induced an increase in HR and BRS accompanied by a decrease in MAP. These effects, except for on BRS, were abolished by concomitant epinephrine injection [100 microg/ kg, subcutaneously (s.c.)]. ABM also induced an increase in serum nitric oxide levels, which was partly antagonized by epinephrine. In summary, oral application of ABM induced a decrease in MAP. Administration of epinephrine sustained the normal range of MAP via nitric oxide regulation, but it has no effect on BRS due to the synchronous changes of MAP and HR in ABM-intoxicated rats.