ABNORMAL CARDIOVASCULAR-RESPONSES TO EXERCISE DURING THE DEVELOPMENT OF OBESITY IN DOGS

This study examined the control of cardiovascular dynamics in response to exercise during the development of obesity in dogs. Left atrial pr essure (LAP), mean arterial pressure, and cardiac output (CO) were det ermined both at rest and in response to treadmill exercise (5.6 km/h, 10% grade) first during a control, lean state and then, once a week wh ile the dogs were maintained on a high fat diet (HFD) for 4 weeks. Bod y weight increased from 22.8 +/- 1.1 to 33.1 +/- 2.0 kg after 4 weeks of HFD. The dogs developed mild hypertension with increases in resting CO, heart rate, and LAP. The response to exercise was characterized b y a decrease in LAP when the dogs were lean and, in contrast, by a dra matic increase in LAP during the development of obesity. In addition, after the third week, the dogs could no longer maintain exercise at th e original level. These results suggest that abnormal left ventricular function may occur very early during the development of canine obesit y.