Effects of some coronary vasodilator drugs on collateral hemodynamics after chronic myocardial ischemia in the anesthetized dog: appropriate or inappropriate redistribution?

These effects of dipyridamole, carbochromen, pentaerythritol tetranitrate (PETN), papaverine and ethaverine on collateral hemodynamics were investigated in anesthetized dogs 5 weeks after experimental coronary occlusion. The retrograde pressure, flow and resistance (RP, RF and RR) and the pressure, flow and resistance of the nonoccluded artery (CP, CF and CR) were measured; the pressure, flow and resistance ratios, i.e., the circulatory relationships which appeared between areas localized on both sides of the well-developed collateral channels, were calculated. Dipyridamole and carbochromen provoked an inappropriate and long-lasting redistribution to the detriment of ischemic areas: RF and RP decreased, whereas CF increased; RP/CP and RF/CF decreased; RR/CR increased. PETN provoked a redistribution in favor of ischemic areas: RF increased and RR decreased; RP/CP and RF/CF increased; RR/CR decreased. These main effects of PETN appeared after a first short period during which the changes in normal and ischemic areas were almost identical. Like PETN, papaverine and ethaverine provoked an appropriate redistribution during a second period. These results are discussed in terms of the selectivity of coronary dilator action on large or small vessels. The methodology used appears to be adequate to evaluate the activities of various drugs on a well-developed collateral coronary circulation.