3H‐Nicotine in cat superior cervical and nodose ganglia after close‐arterial injection in vivo

1. Concentrations of (3)H-nicotine in the superior cervical and nodose ganglia of anaesthetized cats were measured after close-arterial injection.2. Shortly after injection there was a higher concentration of (3)H-nicotine in the superior cervical ganglion than in the nodose ganglion. Mean concentration ratios, superior cervical ganglion/nodose ganglion (S/N ratios) were: 2 min after injection, 1.60 +/- 0.19; 4 min, 1.21 +/- 0.19; 8 min, 0.92 +/- 0.05. These ratios were independent of the dose of nicotine over the range 4 to 200 mug in 0.2 ml.3. There was no comparable difference in the concentrations of injected (14)C-inulin or (3)H(2)O in the two ganglia, or in total water content.4. Procedures which reduced the pharmacological action of nicotine (pre-treatment with hexamethonium, admixture of (14)C-inulin) tended to reduce the S/N ratio for nicotine.5. Autoradiographs showed that nicotine entered the neurones of both superior cervical and nodose ganglia.6. It was concluded that the higher concentration of nicotine in the superior cervical ganglion was probably related to its selective pharmacological action at this site, and may have been due to a greater intracellular retention of nicotine.