Fig. 1. In the newborn piglet, salvinorin A dilated the brain pial artery in a dose-dependent manner (n = 5). (A ) N (G)-nitro-L-arginine (L-NNA), a nitric oxide synthase inhibitor, blocks the dilation effects of salvinorin A, but not sodium nitroprusside (SNP). (B ) Continual administration every 2 min of salvinorin A can sustain dilation of the pial artery for 30 min. (C ) The neuronal NOS inhibitor 7-nitroindazole (7-NINA) did not block the dilation effects of salvinorin A. (D ) Although 100-pM SNP restored the construction effects of L-NNA, it did not restore the dilation effects induced by salvinorin A, which was blocked by L-NNA.