To investigate the growth rate, branching behavior, and orientation of cultured embryonic frog nerves exposed to different stimuli. Cells were treated to DC electric fields, to raised extracellular cations, aminoglycoside antibiotics, or to combinations of these stimuli.
Electric field exposure leads to cathodal orientation and cathodal branching of the neurites, which could be blocked by aminoglycosid antibiotica treatment (Neomycin, Gentamicin, and Tobramycin were used) and by raised extracellular amounts of divalent cations (magnesium and calcium were used) respectively. However, neomycin in combination with high external calcium levels leads to an anodal orientation and branching of the neurites. Aminoglycoside treatment decreased neurite growth rate. In the case of neomycin this effect was reversed by calcium. Growth rate in a field-strength dependet manner was altered by raised calcium but not by magnesium.