The purpose of this Core is to provide for the consistent preparation of animal models across the various projects. It will be the responsibility of this Core to prepare the chronic animal models for individual investigator use. This will reduce the variability of preparations and will release the individual project directors from the extremely labor intensive task of creating these preparations and caring for their immediate post operative recovery. The Core will also provide echocardiograph data on the animals prior to and during the development of heart failure or sham time controls. The various animal models will be prepared by or under the direction of Dr. Cornish who has had many years of experience in the preparation of chronic animals and is experienced in these specific animal preparations. He will be assisted by two technicians in the preparation and care of the animals prior to their use by the various investigators. The models prepared by this core will be (1) the coronary ligation model of heart failure (HF) in the rat, and (2) the pacing model of HF in the rabbit. During the development of the PPG over the past years, the use of the sonomicrometry crystals for providing information relative to ventricular function has shifted to the use of echocardiographic data. This began with work in Dr. Zucker's laboratory but is now being used more generally by the other labs as well. Since there is only one echocardiogram machine available, this function will now become part of the animal core. Ms. Hallgren-Golka will be joining the Core and has been primarily responsible for obtaining data on rats and rabbits prior to, during and after the induction of heart failure. Ms. Hallgren-Golka, with the assistance of Kaye Talbitzer, will now provide this service to the other projects.