Table 1 Summary of sodium channel distribution and potential involvement in pain conditions
Channel | Distribution in normal DRG | Inflammatory pain | Neuropathic pain | Effect of manipulation on behavioral consequences | Human disorders | |||
|---|---|---|---|---|---|---|---|---|
| Â | Â | mRNA | Protein | mRNA | Protein | Antisense/siRNA | Knock out | Â |
1.1 | High in large cells, low in small cells | Unchanged (carrageenan) | Unchanged (carrageenan) | Decreased (SNI, SNL) | N/A | N/A | N/A | Migraine, epilepsy |
1.2 | Very low in most conditions | Unchanged (carrageenan) | Unchanged (carrageenan) | Decreased (SNI, SNL) | N/A | N/A | N/A | Epilepsy |
1.3 | Extremely low in adult DRG | Increased (carrageenan) | Increased (carrageenan) | Increased (SNI, SNL) | Increased (SNI, SNL) | Effective on SCI and CCI, but no effect on SNI | No effect on acute, inflammatory, or neuropathic pain | Accumulates in neuromas of human painful neuropathy |
1.6 | High in large cells, low in small cells | Unchanged (carrageenan) | Unchanged (carrageenan) | Decreased (SNI, SNL) | N/A | N/A | N/A | N/A |
1.7 | Predominantly in small cells | Increased (carrageenan, CFA) | Increased (carrageenan, CFA) | Decreased (SNI, SNL) | Decreased (SNA, SNI, and SNL) | Effective on CFA | Effective on acute and inflammatory pain; no effect on neuropathic pain | Decreased in human injured DRG; accumulates in neuromas; mutations: PE, PEPD, and CIP |
1.8 | Exclusively in small cells | Increased (carrageenan) | Increased (carrageenan) | Decreased (SNI, SNL) | Decreased in L5 DRG (SNL, SNI) but increased in L4 DRG and sciatic nerve | Effective on CFA, SNL, and CCI | Effective on inflammatory pain; no effect on neuropathic pain | Accumulates in neuromas of human painful neuropathy |
1.9 | Selectively expressed in small cells | Increased (CFA), unchanged (carrageenan) | Unchanged (carrageenan) | Decreased (SNA, SNI, and SNL) | Decreased (SNA, SNI, and SNL) | No effect on SNL | Effective on inflammatory pain; no effect on neuropathic pain | N/A |