Fig. 3. Quantitative evaluation of enteric neuron migration after chemical manipulation of the NO/cGMP pathway and HO enzymes. Bar plots show average migration distance covered by the leading enteric neurons during 24 hours of in vivo culture. Data result from at least two independent experiments, each normalized to the mean of the corresponding control. (A) Inhibition of NOS with 500µM 7-NI or scavenging NO with 500µM hemoglobin result in a significant reduction of migration on dorsal migratory pathways. (B) Excess of NOS substrate L-arginine (2 mM) or stimulation of sGC with 65µM YC-1 revealed no difference of migration compared with the control. (C) Inhibition of CO releasing HO enzymes with 10µM ZnPP-IX or 5µM ZnBG lead to a significant acceleration of enteric neuron migration. Activating HO with 100 µM hemin or applying CORM-II (20µM) resulted in a significant reduction of average migrated distance. Application of inactivated CORM-II (iCORM-II, 20µM) did not affect migration. (D) Enteric neuron viability after 24 hours of in vivo culture with 100µM hemin or 200µM CORM-II. 100% represents total number of counted enteric neurons. Error bars are ±s.e.m. The numbers of experimental gut preparations are indicated in the bars. A Wilcoxon Mann-Whitney test was employed for statistical comparisons. ^***P<0.001; ^**P<0.005; ^*P<0.05.