Participation of nitric oxide in regional coronary bloodflow regulation during myocardial ischemia in the canine heart (part 5)

4 Sep

The effect of NONLA was considered adequate when the response of circumflex coronary flow to the intracoronary administration of acetylcholine (5.5 nmol/kg diluted in 0.5 mL saline) was reduced by at least 80% . Fifteen minutes later ischemia was again induced by decreasing the peripheral coronary pressure, and regional flow was measured with the microspheres as detailed above. After the experiments the heart was excised. The circumflex coronary artery was perfused with a solution of Evans Blue in saline at a pressure of 100 mmHg and, simultaneously, the anterior descending coronary artery was perfused with pure saline at the same perfusion pressure to differentiate the ischemic from the nonischemic zone.A piece of ventricular wall was obtained from the centre of the ischemic region and of the nonischemic region; each of these was split into four layers across the thickness of the wall, and each layer was weighed. The radioactivity of the tissue samples (Cm) and of the blood samples obtained from the reference flow (Cr) was measured separately in a gamma spectrometer equipped with a multichannel analyzer and a minicomputer to carry out isotope separation computation (Packard Auto Gamma 5500, Packard Instruments Company, Meriden, Connecticut, USA). Coronary flow to each of these regions (Qm) was calculated by the equation. Take advantage of this chance to find Generic Tavist and save quite some money.

where Qr is the flow rate of the reference sample (10 mL/min). Flow was expressed per 100 g of tissue.