VASOMOTOR RESPONSES IN RATS INTOXICATED WITH DOXORUBICIN

In rats intoxicated with doxorubicin, vasomotor responses were evaluat ed 12 hr after the last dosage. In rats pretreated with doxorubicin, h ypertensive responses to L-norepinephrine and L-epinephrine, and hyper tension by occlusion of both common carotid arteries were significantl y (p < 0.05) reduced when compared with controls. Doxorubicin pretreat ment also significantly reduced the arterial hypotension due to L-isop renaline. In rats intoxicated with doxorubicin, pretreatment with L-su lpiride (12.5 to 50 mg/Kg/day for 30 days in drinking water ad libitum ) did not modify the effects of doxorubicin on vasomotor reactivity. I n contrast, pretreatment with amitriptyline (12.5 to 50 mg/Kg/day in d rinking water ad libitum for 30 days) potentiated the inhibitory effec ts of doxorubicin on vasomotor responses. In conclusion, our research shows that doxorubicin intoxication induces a significant reduction of alpha- and beta-adrenergic reactivity and of baroreceptor activity.