A–C: effects of PKC activation, via topically applied phorbol 12,13-dibutyrate (PdBu, 10 nM), on pial arteriolar responses in experiments involving only nondiabetic control animals. PdBu markedly inhibited dilations induced by the BKCa agonist NS-1619 (A), the Kir agonist K+ (B), and SNS (C) (n = 5 for all, *P < 0.05 vs. initial responses).