Distribution of Local Anesthetic Agents in the Neuraxis of the Dog

Autoradiographic studies of the spinal cord in the dog indicate a specific uptake of C-Iabelled lidocaine and procaine by the neuraxis. The highest concentrations of the intrathecally-adminis-tered drug were found in the posterior and lateral columns, with only small concentrations noted in the anterior columns. Uptake of drug was higher in the grey matter than in the white matter of the cord, and posterior nerve roots had a higher concentration than anterior roots. Biopsies of the cord and scintillation counting of the weighed specimens provided confirmation of the autoradiographic studies. The significance of these findings is discussed, and possible explanations arc considered.