Intracranial pressure and CSF outflow relationships upon intranasal delivery of pharmacological agents. Shown are representative examples of pressure/flow curves of (A) saline delivery, (B) noradrenaline (NA) at 50 μM and 500 μM, (C) L-NMMA treated at 10 μM and 100 μM and (D) U46619 treated at 0.1 μM and 1.0 μM and (E) U46619 at 1 mM. (A to D) In each experiment (○) represents no treatment (NT), (□) represents the first intranasal delivery, and (×) represents the second intranasal delivery. (E) No treatment is represented by (○), and 1 mM U46619 represented by (□). Linear regression lines for each treatment are shown.