Effect of antihypertensive therapy on focal stroke in spontaneously hypertensive rats.

Spontaneously hypertensive rats subjected to focal cerebral ischemia develop larger infarcts than normotensive rat strains. To determine whether antihypertensive therapy decreases infarct volume in hypertensive rats, 60 13-week-old animals were treated with 20 mg/kg hydralazine added daily to the drinking water for 1.5, 6, 10, or 16 weeks and then subjected to focal cerebral ischemia by tandem right common carotid artery and middle cerebral artery occlusion. Blood pressure in the treated groups was substantially lower than that in untreated groups after 1 week of hydralazine therapy and remained lower for the entire treatment period in all four experiments. Mean infarct volume in spontaneously hypertensive rats treated for 10 (p = 0.02) or 16 (p = 0.005) weeks, but not 1.5 or 6 weeks, was significantly less than that in the untreated controls. The percentage reduction of infarct volume in animals treated for 10 and 16 weeks was similar. This study demonstrates that antihypertensive therapy decreases infarct volume in hypertensive rats subjected to focal cerebral ischemia. This treatment effect appears to be dependent on the duration of therapy, and the magnitude of the treatment effect seems to plateau by 10 weeks of therapy.