Fig. 3

Effect of COX inhibitors on dural vasodilation, induced by repeated sodium nitroprusside infusions, 2 μg kg⁻¹ min⁻¹ over 5 min intra arterial, in intravital microscopy (a) and on the blood pressure decrease caused by the repeated infusion of sodium nitroprusside prior and post drug or control administration (b). After the baseline response was established one of the drugs (indomethacin 5 mg kg⁻¹, naproxen 30 mg kg⁻¹ or ibuprofen 30 mg kg⁻¹) was applied intravenously, followed by four further sodium nitroprusside infusions with a 15 min recovery period, starting 10 min after the administration of one of the drugs. Of all drugs used only indomethacin shows an inhibitory effect on nitric oxide induced vasodilation as well as on the blood pressure decrease induced by the infusion of sodium nitroprusside. *P < 0.05