ANIMALS AND METHODS
The present study was conducted in accordance with the “Position of the American Heart Association on Research and Animal Use” and the guidelines of the Animal Care Committee of the Faculty of Medicine of the University of Chile. Surgical preparation of dogs: Fourteen mongrel dogs of either sex between 11 and 17 kg body weight were anesthetized with sodium pentobarbital (30 mg/kg intravenously). The lungs were ventilated through an endotracheal tube with room air by means of a volume- and frequency-regulated pump. Pressure in the root of the aorta was measured with an extracorporeal pressure transducer (Statham P23 Db, Hato Rey, Puerto Rico) connected to a polyethylene catheter implanted through the right brachiocephalic trunk.Left intra-ventricular pressure was measured with a catheter tip manometer (Millard Mikro-Tip catheter pressure transducer, Millard Instruments, Inc, Houston, Texas, USA) inserted through the apex of the heart, and its first derivative in time (dP/dt) was electronically obtained. A connection was established between the left brachiocephalic trunk and the circumflex coronary artery with tygon tubing. Flow was measured in this connection with an extracorporeal bloodflow probe connected to an electromagnetic flowmeter (BL-610, Biotronex Laboratory Inc, Kensington, Maryland, USA). Find best deals online – cialis super active online pharmacy click here can be available every time you visit.