Axotomy increases plasma membrane Ca2+ pump isoform4 in primary afferent neurons

The expression of plasma membrane Ca-ATPase, a calcium pump located in cell membrane regulating intracellular Ca levels by Ca extrusion from cells, was examined in dorsal root ganglion neurons in naive rats and after spinal nerve ligation. The mRNAs and proteins in plasma membrane Ca-ATPase 1–3 were expressed in all size neurons with intense labeling in medium to large neurons. After spinal nerve ligation, these three isoforms showed downregulation of their expression. In contrast, plasma membrane Ca-ATPase 4 was expressed mainly in small neurons, and the number and signal intensity were significantly increased after spinal nerve ligation. These data suggest that plasma membrane Ca-ATPase isoforms have a distinct pattern of expression and regulation by axotomy in dorsal root ganglion neurons in normal and pathological conditions.