Congenic removal of a QTL for blood pressure attenuates infarct size produced by middle cerebral artery occlusion in hypertensive rats.

A genome-wide screen found a blood pressure quantitative trait locus (QTL) on rat chromosome 1 in stroke-prone spontaneously hypertensive rats of a Japanese colony (SHRSP/Izm). In the present study, we investigated the effects of congenic removal of this QTL from SHRSP/Izm on infarct size produced by middle cerebral artery (MCA) occlusion. To establish the congenic strain (SHRSPwch1.0), the blood pressure QTL was introgressed from Wistar-Kyoto (WKY)/Izm to SHRSP/Izm by repeated backcrossing. Male SHRSP/Izm [10–12 wk old (young adult) n = 8, 5 mo old (adult) n = 17] and SHRSPwch1.0 (young adult n = 7, adult n = 15) were randomly assigned to distal MCA occlusion. Resting mean arterial blood pressure (MABP) was 212 ± 23 mmHg in adult SHRSPwch1.0, which was significantly lower than 241 ± 22 mmHg in SHRSP/Izm. Infarct volume in the congenic rats was significantly decreased compared with that in SHRSP/Izm (66.4 ± 21.5 mm3 vs. 103.4 ± 24.8 mm3). Cerebral blood flow (CBF), determined at collaterally-perfused cort...