Soluble guanylyl cyclase-cGMP signalling mediates semaphorin 3A-induced growth cone collapse in sympathetic neurones. (A) Inhibition of sGC (ODQ) prevented Sema3A-induced growth cone collapse and stimulation of sGC (SNP) also caused collapse. (B) In contrast to parasympathetic neurones, inhibition of AC (DDA) did not prevent Sema3A-induced growth cone collapse in sympathetic neurones. However, stimulation of AC (FSK) did cause growth cone collapse. (C) Neither cAMP- nor cGMP-dependent phosphodiesterase inhibition (ROL and ZAP, respectively) augmented Sema3A-induced growth cone collapse, nor did these inhibitors significantly affect collapse on their own. However, when added together, ROL and ZAP caused growth cone collapse. Tukey's test: *P < 0.05, **P < 0.01, ***P < 0.001 versus control; ###P < 0.001 versus Sema3A (n= 4 for all experiments). DDA, 2′,5′-dideoxyadenosine; FSK, forskolin;; ROL, rolipram; Sema3A, semaphorin 3A; SNP, sodium nitroprusside; ZAP, zaprinast.