Deleterious Effects of Hypertension on the Development of Aortic and Coronary Atherosclerosis in Stumptail Macaques (Macaca Speciosa) on an Atherogenic Diet

Utilizing the stumptail macaque, we studied the atherosclerotic lesions produced in the aorta and coronary arteries by an atherogenic diet alone and by the diet coupled with hypertension produced by a modified Goldblatt technique. One group of monkeys was subjected concomitantly to the diet and hypertension for 10-12 months; a second group was on the diet for 29-32 months, but hypertension was induced for only the last 7-9 months of this period. In both of these groups, hypertension led to more severe lesions in the aorta. When an index of coronary involvement was plotted as a function of either arterial systolic or diastolic blood pressure, a significant correlation was found in both groups of monkeys. Additionally, in the monkeys with hypertension, morphologic criteria indicated that increased amounts of elastic fibers were present in the plaques in a disorganized, fragmented manner; in the monkeys on the diet alone, the elastic fibers were disposed in well-formed, reduplicated lamellas. Fat deposition was also different between these two groups: fat was located in the depths and at the periphery of the lesions in the hypertensive monkeys, whereas it was evenly dispersed throughout the plaques in the monkeys on the atherogenic diet alone. Thus, hypertension coupled with an atherogenic diet increases the extent of aortic and coronary lesions in proportion to the elevation in arterial blood pressure and, furthermore, may modify the morphologic characteristics of the lesions.