Cerebral Endothelial Function Determined by Cerebrovascular Reactivity to L-Arginine

Table 1

Types of nitric oxide synthase and their role in cerebral ischaemia [17].

nNOS (NOS I)	iNOS (NOS II)	eNOS (NOS III)
Activity depends on elevated Ca^2+	Activity is independent of Ca^2+	Activity depends on elevated Ca^2+
First identified in neurons	First identified in macrophages	First identified in endothelial cells
Constitutively expressed, but inducible under pathological conditions	Inducible under pathological conditions	Constitutively expressed, but inducible under pathological conditions
Plays a prominent role in the early stage of neuronal injury after cerebral ischemia	Plays a role in the later stages of neuronal injury after cerebral ischemia	Plays a protective role in cerebral ischemia by maintaining cerebral blood flow
Protein and catalytic activity upregulated within 10 minutes and peak at 3 hours after cerebral ischemia	Protein and catalytic activity upregulated within 12 hours and peak at 48 hours after cerebral ischemia	Protein and catalytic activity upregulated within 1 hour and peak at 24 hours after cerebral ischemia