Captopril Treatment Temporarily Restores Cerebral Blood Flow Autoregulation in Spontaneously Hypertensive Rats After Hemorrhagic Stroke

Hemorrhagic stroke development in stroke-prone spontaneously hypertensive Kyoto Wistar rats (SHRsp) is associated with a loss of cerebral blood flow (CBF) autoregulation and death. We assessed the ability of poststroke captopril treatment to retard death and restore CBF autoregulation in SHRsp. Laser Doppler techniques were used to measure alterations in CBF with varying mean arterial pressure (MAP) in anesthetized SHRsp. Three weeks before stroke, all SHRsp autoregulated near constant CBF to an upper MAP limit of 155 +/- 4 mm Hg. CBF autoregulation was absent in half of the SHRsp at 0.5-2 weeks before stroke and nonexistent in SHRsp with stroke. Captopril treatment (50 mg.kg(-1).d(-1)) initiated at the first signs of stroke (seizures) increased the lifespan of SHRsp from 10 +/- 3 to 124 +/- 18 days without lowering blood pressure and restored CBF autoregulation within 10 days. CBF autoregulation subsequently deteriorated where after 25 days of treatment, only 2 of 5 SHRsp maintained the ability to autoregulate CBF. We concluded that captopril treatment retarded death and new hemorrhage formation after stroke. The early restoration of autoregulation could prevent sudden death after stroke, but other mechanisms associated with poststroke captopril treatment act to prolong life in the presence of hypertension and absence of CBF autoregulation.