Age as a modifying factor on the effect of antihypertensive therapy in focal stroke in rats

Antihypertensive treatment with hydralazine for 10 weeks but not 6 weeks reduces infarct size in 13-week-old spontaneously hypertensive rats subjected to focal cerebral ischemia. This study was designed to examine whether the duration of treatment needed to reduce infarct size depends on how long hypertension is present before the initiation of antihypertensive therapy.

Six-week-old spontaneously hypertensive rats were treated for 6 weeks and 10-month-old spontaneously hypertensive rats for 10 weeks with 20 mg/kg hydralazine added daily to the drinking water. The animals were then subjected to focal cerebral ischemia by tandem permanent common carotid and middle cerebral artery occlusion.

Blood pressure in the treated groups was lower than that in the untreated groups for the entire treatment period in both experiments. Infarct volume in 10-month-old spontaneously hypertensive rats treated for 10 weeks, but not in 6-week-old spontaneously hypertensive rats treated for 6 weeks, was significantly less than in untreated controls (p = 0.02).

This study emphasizes the importance of duration of antihypertensive treatment in reducing infarct volume in spontaneously hypertensive rats after focal cerebral ischemia and demonstrates that the effect appears to be independent of the duration of hypertension before the initiation of treatment.