Experimental design: After the surgical procedure a period of 15 mins was allowed for hemodynamic variables to stabilize. The following protocol was followed in each of the 14 dogs. Ischemia was induced by decreasing the peripheral coronary pressure with the occluder from its control value to a pressure of about 25 mmHg. After 1 min of ischemia, regional coronary flow was measured with radioactive microspheres (15±5 |j.m in diameter labelled with 46Sc or 57Co) injected into the left atrium, while a reference flow value from a femoral artery was obtained as previously described . The duration of the measuring procedure (injection of the microspheres and collection of the reference sample) was 90 s; therefore, the total duration of ischemia was 150 s.The amount of microspheres injected was calculated to deliver at least 500 microspheres to the ischemic region of interest in order to avoid measurement errors greater than 10% with 95% CI . Then the artery was reopened and, provided that the hemodynamic conditions were similar to those of the control period, synthesis of nitric oxide was inhibited with the intravenous administration of a bolus of 30 mg/kg of N-omega-nitro-L-arginine (NONLA) dissolved in saline. NONLA is a strong inhibitor of nitric oxide synthesis deprived of a muscarinic receptor antagonism. You will always be offered Purchase Zyrtec at the pharmacy you can trust.