Figure 3.

The effects of L-NAME (100 μM) on the tone of endothelium-containing and endothelium-denuded rings of porcine cerebral artery, pre-constricted with the half-maximal effective concentration (EC₅₀) of (a) U46619 (10–30 nM) or (b) 5-HT (10–30 nM). Each value is the mean±s.e.mean of 6–10 observations. ^**P<0.01 and ^***P<0.001 respectively indicate where L-NAME produced a significant augmentation of 5-HT- and U46619-induced tone.