Cerebral Arteries/metabolism; Cerebrovascular Circulation; Hydroxyeicosatetraenoic Acids/metabolism; Hypertension/complications; Infarction, Middle Cerebral Artery/complications; Oxidative Stress; Stroke/etiology; Amidines/pharmacology; Animals; Blood Pressure; Cerebral Arteries/drug effects; Cerebral Arteries/pathology; Cerebral Arteries/physiopathology; Cerebrovascular Circulation/drug effects; Cytochrome P-450 CYP4A/metabolism; Disease Models, Animal; Enzyme Inhibitors/pharmacology; Hypertension/metabolism; Hypertension/pathology; Hypertension/physiopathology; Infarction, Middle Cerebral Artery/metabolism; Infarction, Middle Cerebral Artery/pathology; Infarction, Middle Cerebral Artery/physiopathology; Isoenzymes/metabolism; Male; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Reactive Oxygen Species/metabolism; Severity of Illness Index; Stroke/metabolism; Stroke/pathology; Stroke/physiopathology; Stroke/prevention & control; Time Factors; Up-Regulation