Figure 1.

Representative recordings from two separate experiments illustrating the time course of changes in basilar artery diameter in response to (a) sodium nitroprusside and (b) acetylcholine obtained under control conditions and in the presence of 4-aminopyridine (4-AP, 200 μM). Two concentrations of each vasodilator were applied to the cranial window in a cumulative manner for 2–3 min each, until a steady-state response was achieved. Responses to both vasodilators were attenuated during treatment of the cranial window with 4-AP.