EFFECT OF CHRONIC ANG I-CONVERTING ENZYME-INHIBITION ON AGING PROCESSES .4. CEREBRAL BLOOD-FLOW REGULATION

Age-related changes in systemic arterial blood pressure, basal cerebra l blood flow (CBF), and CBF regulatory capacity were investigated in a wake 6-, 12-, 24-, and 30-mo-old male Wistar (WAG/Rij) rats, one-half of which received the angiotensin I-converting enzyme inhibitor (ACEI) perindopril from 6 mo onward. There was no age-dependent change in me an arterial blood pressure, basal CBF, or cerebrovascular reactivity t o hypercapnia, but the lower limit of CBF autoregulation rose from 70 mmHg at 6 and 12 mo to 90 mmHg in 24- and 30-mo-old animals. ACEI lowe red mean arterial blood pressure but had no effect on basal CBF or on cerebrovascular reactivity to hypercapnia. ACEI shifted the lower limi t of CBF autoregulation to a 20-mmHg-lower level in 12- and 24-mo anim als but not in rats treated for 2 yr, i.e., from the ages of 6 to 30 m o. In conclusion, the main age-related change in CBF regulation was an increase in the lower limit of CBF autoregulation to a higher blood p ressure level. Treatment with ACEI partially restored the lower limit of CBF autoregulation.