Distribution of N(omega)-nitro-L-arginine following topical and intracerebroventricular administration in the rat.

The distribution of the nitric oxide synthase inhibitor, N(omega)-nitro-L-arginine (L-NA), in the rat brain following either topical or intracerebroventricular application was examined using 14C-labeled L-NA. Two hours after topical application, the concentration of L-NA 1 mm below the surface was approximately 20% of the concentration at the surface, and less than 3% at 2 mm below the cortical surface. L-NA infused into the lateral cerebral ventricle distributes only in regions in close proximity to the ventricle even 8 h after administration. Consequently, intracerebroventricular administration of nitric oxide synthase inhibitors may not be useful if global inhibition of nitric oxide synthase is desired.