Obesity-induced hypertension in the dog

Abstract

To study the relationship between body weight and blood pressure, we have developed an animal model of obestiy-induced hypertension. Nine adult mongrel dogs were chronically instrumented with aortic and vena caval catheters. After a 2-week control period, all dogs were made to gain weight by adding 2 Ib/day of beef fat to their diet for 5 weeks. Blood pressure, heart rate, and body weight were measured daily before the addition of dietary fat, during the 5 weeks of the high fat diet, and for 6 weeks after the fat supplement was stopped. Plasma volume and cardiac output were measured prior to and after 5 weeks of the fat diet. During the 5-week high fat diet, the dog's body weight increased from 22.2 ± 2.1 to 27.4 ± 3 kg (p < 0.001); mean blood pressure increased from 90 ± 5 to 112 ± 6 mm Hg (p < 0.01); and heart rate increased from 70 ± 7 to 85 ± 5 beats/min (p < 0.05). Blood pressure, heart rate, and body weight returned to near control values after the fat diet was stopped. Over the 5-week fat diet, the dog's plasma volume increased from 920 ± 130 to 1059 ± 195 ml (p < 0.05); cardiac output increased from 2.5 ± 0.4 to 3.1 ± 0.3 L/min (p < 0.05); and systemic vascular resistance increased from 35.3 ± 8 to 38.9 ± 9 mm Hg/L/min (p < 0.1). Weight gain in the dogs was also associated with hyperinsulinemia and insulin resistance. Our findings have demonstrated that weight gain in the dog is associated with an increase in heart rate, blood pressure, cardiac output, plasma volume, and fasting insulin concentration, and we think that our animal model should be ideal for studying the pathogenesis of obesity-induced hypertension. © 1987 American Heart Association, Inc.