Protective effect of treatment with nicardipine on cerebrovascular tree of spontaneously hypertensive rats

The effect of an eight-week treatment with the Ca²⁺ channel blocker nicardipine on different-sized pial arteries and intracerebral arteries was assessed in spontaneously hypertensive rats (SHR) by microanatomical techniques. Normotensive Wistar-Kyoto (WKY) rats were used as normotensive reference animals. In SHR a significant increase of systolic blood pressure (SBP) in comparison with WKY rats was noticeable. An increased thickness of tunica media and luminal narrowing were also seen in medium- and small-sized pial arteries, and in intracerebral arteries of SHR in comparison with WKY rats. The media-to-lumen ratio was also increased in medium (diameter between 150 and 50 μm) and small-sized (diameter < than 50 μm) pial and intracerebral arteries. Treatment with nicardipine significantly reduced SBP. the thickness of tunica media, media-to-lumen ratio and increased luminal area of medium and small-sized pial arteries and of intracerebral arteries. These findings demonstrate that treatment of SHR with nicardipine induces a moderate vasodilatation of both pial and intracerebral arteries regulating cerebrovascular resistance.