Comparison of succinate dehydrogenase activity and soma size relationships among neurons in dorsal root ganglia of rats and cats

Compared to dorsal root ganglion (DRG) neurons at L(5) in rats, DRG neurons at L(7) in cat have a larger mean soma size, a bimodal rather than unimodal distribution of sizes and lower succinate dehydrogenase (SDH) activities for neurons of all sizes. In contrast to spinal motoneurons in both cats and rats, the larger DRG neurons have the higher SDH activities. The 10-20% higher SDH activity of DRG cells in rats than in cats may reflect, in part, a species difference of about 40% in metabolic rates.