Fixler D. Reduced myocardial reflow and increased coronary vascular resistance following prolonged myocardial ischemia in the dog. Circ Res. 1975;36: 771–781

Studies were performed to determine whether an alteration in coronary vascular resistance and a reduction in the reflow phenomenon occurred in the blood-perfused, heparinized canine heart after various periods of myocardial ischemia. Regional myocar-dial blood flow was measured with radioactive microspheres. Proximal left anterior descending coronary artery blood flow was measured with a periarterial flow transducer. Reduced reflow to the ischemic portion of the left ventricle and increased resistance in the left anterior descending coronary artery were present after 120 minutes of myocardial ischemia. The reduction in reflow was specific to the subendocardium of the ischemic area. Saline and isosorbide dinitrate (Isordil) did not prevent the increase in coronary vascular resistance or the significant reduction in reflow to the subendocardial portion of the ischemic area. Hypertonic mannitol given so as to increase serum osmolality 40 mosmoles/kg prevented the increase in coronary vascular resistance and modified the reduction in the reflow phenomenon to the subendocardial portion of the ischemic area. Thus, both an increase in coronary vascular resistance and a significant reduction i