Cocaine has many adverse effects on the heart, to the point that when people under 40 years of age appear in an emergency room with a heart attack is a good guest hat it was precipitated y cocaine. In experiments, cocaine has been shown to constrict coronary arteries and reduce blood flow lo the hean muscle as well as depress the overall mechanical function of the heart. A class of drugs know as calcium channel blockcrs has been us€d to treat problems associated with coronary artery asoconstrictionin other contexts o SharonH ale and colleagues ("Nifedipine Protects the Heart from the Acute Deleterious Effects of Cocaine if Administercd Before but Not Atier Cocaine," Circulation, 83:1437-1443, 1991) hypothesized that the calcium channel blocker nifedipine could prevent coronary artery vasoconstriction and the attendant reduction in blood flow to the heart and mechanical function. If true, nifedipine might be useful for treating people who had heart problems brought on by cocaine use. They measured mean arterial pressure in two groups of dogs after administering cocaine, one of whom was treated with nifcdipine and the other of which received a Placebo.