Effects of cocaine on canines' coronary arteries

Nine canines were anesthetized with pentobarbital and studied by both selective and semiselective coronary artery angiography following intravenous bolus doses of 1,3,5,8, or 10 mg/kg of cocaine. Catheterization was accomplished with a 5 Fr catheter over a 0.035 inch guidewire under fluoroscopic control, and angiograms were obtained by injection of a diatrizoate solution. Digital subtraction angiography (DSA) was performed prior to cocaine administration and at minutes 0.5, 1, 1.5, 3, 5, and, in some cases, minutes 10 and 15 after cocaine administration. The 1 and 3 mg/kg doses of cocaine had no effect on the coronary arteries. The 5 mg/kg dose significantly dilated the coronary arteries. The 8 mg/kg dose produced significant dilation at 30 seconds after cocaine but nonsignificant dilation of the coronary arteries at all other times. The 10 mg/kg dose produced significant dilation at 30 seconds, nonsignificant dilation at 60 seconds followed by significant constriction at 90 seconds after cocaine, which led to immediate death in most animals. The coronary dilation and constriction produced by 10 mg/kg of cocaine could be prevented by either preadministration or postadministration of naloxone, but this did not prevent subsequent death.