Calcitonin reduces steady ionic current of the growth plate

We tested the hypothesis that calcitonin regulates the electric current associated with ionic exchanges occurring at the growth plate. For this purpose, we measured the net outward current driven by the growth plate of metatarsal bones of weanling mice by means of a voltage-sensitive probe system vibrating in two dimensions. Current density was reduced by calcitonin in a dose-dependent manner. Maximal reduction (-40%) was obtained at a calcitonin concentration of 5 IU/ml. No effect was observed for calcitonin concentrations ≤ 0.05 IU/ml. When chloride was removed from the medium, calcitonin was less effective in reducing the net current density. Neither calcitonin gene-related peptide nor clodronate was able to induce any measurable change of the current density. Our results indicate that calcitonin acts on the ionic exchanges occurring at the growth plate and suggest that endogenous electrical signals in bone might be modulated by hormones.