Smooth Muscle Apoptosis During Vascular Regression in Spontaneously Hypertensive Rats

Abstract

We previously reported that apoptosis is increased in smooth muscle cells cultured from the aorta of spontaneously hypertensive rats versus normotensive controls. As an initial in vivo exploration, we now examined smooth muscle cell apoptosis regulation during the regression of vascular hypertrophy in the thoracic aorta media of spontaneously hypertensive rats receiving the antihypertensive drug enalapril (30 mg·kg−1·d−1), losartan (30 mg·kg−1·d−1), nifedipine (35 mg·kg−1·d−1), hydralazine (40 mg·kg−1·d−1), propranolol (50 mg·kg−1·d−1), or hydrochlo-rothiazide (75 mg·kg−1·d−1) for 1 to 4 weeks starting at 10 to 11 weeks of age. Three criteria were used to evaluate smooth muscle cell apoptosis: (1) oligonucleosomal fragmentation of the extracted aortic DNA, (2) reduction in aortic DNA content, and (3) depletion of smooth muscle cells in the arterial media. Arterial DNA synthesis was evaluated by [3H]thymidine incorporation in vivo. After 4 weeks of treatment, systolic blood pressure was reduced significant...