Baseline cerebral blood flow (CBF) (A) and cerebral arterial blood volume (CBVa) (B) of five regions of interest (ROIs) under the normocapnic condition. All 12 animal data for each group were averaged. Spontaneously hypertensive rats (SHR) had slightly lower CBF values as compared with Wistar–Kyoto rats (WKY), whereas CBVa values were signtificantly lower in most areas, particularly in the hippocampus (*P<0.05, **P<0.01). Error bars: s.e.m. (n=12); CPU, caudate putamen; Th, thalamus; Hip, hippocampus.