Aortic atherosclerosis in hypertensive rabbits treated with anti-hypertensive agents having different effects on...

Hypertension may be considered a disorder of increased energy in the blood, with two components: increased pressure energy may promote arteriolar disease, whereas arterial diseases such as atherosclerosis may be more closely related to flow disturbances (turbulence, boundary layer separation, high shear, or axial stream impingement) due to increased kinetic energy. Previous studies have shown that hydralazine aggravates turbulence in stenosed carotid arteries, whereas propranolol diminishes turbulence. To assess the effect of these drugs on the progression of atherosclerosis, the drugs were administered subcutaneously to rabbits made hypertensive (one kidney Goldblatt) and hypercholesterolemic (1% cholesterol diet for 4 weeks). Appropriate controls with normal, only hypertensive and hypertensive-hypercholesterolemic untreated rabbits were employed. A total of 36 rabbits was used. The extent of the aortic surface involvement with atherosclerotic lesions was assessed by morphometric analysis of magnified photographs. Although the extent or surface involvement did not differ significantly between the untreated or treated hypertensive rabbits, there was an interesting difference in the relationship between blood pressure and extent of surface involvement. In the untreated and hydralazine treated rabbits, there was a direct correlation between increasing blood pressure and extent of lesions; in the propranolol treated group, this relationship was abolished.