Effects of captopril and propranolol on cognitive function and cerebral blood flow in aged hypertensive rats.

Chronic hypertension has been reported to produce adverse cognitive effects in elderly individuals, perhaps by altering central nervous system hemodynamics. The beneficial or adverse effects of antihypertensive drugs on these processes are not well understood. We examined the effects of captopril (90 mg/kg/day) and propranolol (80 mg/kg/day) on cognitive function and brain blood flow in hypertensive and normotensive rats. Cognitive function was assessed by the Morris water maze, and regional brain blood flow was measured by the [14C]iodoantipyrine method. Nineteen-month-old propranolol-treated hypertensive rats exhibited poorer performance (p < .05) than control rats and had lower brain blood flows, particularly in white matter regions (p < .01). Captopril-treated hypertensive rats did not differ significantly from control rats with regard to either cognitive performance or brain blood flow. In the normotensive rats, there were no effects of either drug on cognitive performance or brain blood flow. Thus, blood pressure reduction by propranolol but not captopril has an adverse effect on cognitive function and brain blood flow in hypertensive rats.