Obesity-induced hypertension in the dog

To study the relationship between body weight and blood pressure, we have developed an animal model of obesity-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 lb/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 dogs' body weight increased from 22.2 +/- 2.1 to 27.4 +/- 3 kg (p less than 0.001); mean blood pressure increased from 90 +/- 5 to 112 +/- 6 mm Hg (p less than 0.01); and heart rate increased from 70 +/- 7 to 85 +/- 5 beats/min (p less than 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 dogs' plasma volume increased from 920 +/- 130 to 1059 +/- 195 ml (p less than 0.05); cardiac output increased from 2.5 +/- 0.4 to 3.1 +/- 0.3 L/min (p less than 0.05); and systemic vascular resistance increased from 35.3 +/- 8 to 38.9 +/- 9 mm Hg/L/min (p less than 0.1). Weight gain in the dogs was also associated with hyperinsulinemia and insulin resistance.(ABSTRACT TRUNCATED AT 250 WORDS)