Very early aortic responses during atherosclerosis induction in rabbits: measurement by duplex ultrasound. I. Non-invasive study of aortic hyperresponsiveness to serotonin.

We report the use of a non-invasive ultrasound method to visualize and measure changes in serotonin reactivity of the abdominal aorta during the early stages of atherosclerosis development. Studies were performed at 0, 4, 8, and 14 weeks in New Zealand white rabbits fed a diet enriched with 0.5% cholesterol. Change in systolic vessel diameter at each examination was compared with changes in rabbits fed a control diet or rabbits on a diet enriched with cholesterol plus a concentrated marine lipid. After 4 weeks on the diets, the abdominal aortae of rabbit fed the cholesterol-rich diet displayed an enhanced vasoconstriction to serotonin (P less than 0.01). The enhanced vasoconstriction was observed prior to visible morphologic changes, and progressed when restudied at succeeding examinations. Morphologic abnormalities became evident at 8 weeks in cholesterol-fed animals. Dietary supplementation with marine lipid, rich in polyunsaturated fatty acids, diminished the effect of the atherogenic diet on aortic vasoconstriction.