Arterial baroreflex - A novel target for preventing stroke in rat hypertension

Background and Purpose - Arterial baroreflex is one of the most important mechanisms in the regulation of cardiovascular activities. Arterial baroreflex function can be expressed as baroreflex sensitivity ( BRS). The present study was designed to test 2 hypotheses: ( 1) BRS is a new independent predictor for the incidence of stroke in hypertension, and ( 2) restoration of BRS can prevent stroke in hypertension. Methods - First, 82 stroke- prone spontaneously hypertensive rats ( SHR- SP) aged 28 to 30 weeks were used. After measuring blood pressure and BRS, the survival time was observed. Second, 12 SHR- SP aged 8 months were used. Blood pressure and BRS were determined separately before and after intragastric administration of ketanserin ( 0.3 and 3.0 mg/ kg). Third, SHR- SP aged 5 months were treated with ketanserin for 12 weeks ( 0.3 mg and 3.0 mg/ kg per day). At the end of the treatment, blood pressure and BRS were determined and the end- organ damage was evaluated. Last, SHR- SP aged 3 months were treated with ketanserin ( 0.3 and 3.0 mg/ kg per day) for life and the survival time was recorded. Results - Stroke was significantly delayed in rats with high BRS than those with low BRS ( time to 50% death was 1.47- fold longer than low BRS group; P < 0.01). Ketanserin of 3.0 mg/ kg per day decreased blood pressure and enhanced BRS, whereas 0.3 mg/ kg per day only enhanced the BRS. Fatal stroke incidences were markedly reduced by treatment with both doses ( P < 0.0001 versus control group). Conclusions - The present study provides evidence that BRS is an independent predictor for stroke in hypertension. Restoration of BRS may be a new strategy for the prevention of stroke.