Table 3.
Percentage contributions of PMN and MH only units to the total DRG neuron population
| 3a | % contribution of PMNs to the DRG |
|||
|---|---|---|---|---|
| C | Aδ | Aβ | ALL | |
| Superficial | 6.78 | 0.1 | 0.99 | 7.87 |
| Dermal | 3 | 0* | 0 | 3 |
| Deep | 0 | 0* | 0 | 0 |
| Totals | 9.78 | 0.1 | 0.99 | 10.87 |
| 3b | % contribution of MH + MHC units to the DRG |
|||
|---|---|---|---|---|
| C | Aδ | Aβ | ALL | |
| Superficial | 5 | 0.1 | 0.66 | 5.76 |
| Dermal | 1 | 0* | 0 | 1.0 |
| Deep | 0 | 0* | 0 | 0 |
| Totals | 6.0 | 0.1 | 0.66 | 6.76 |
Table 3a To obtain estimates of the numbers of all PMNs or of the MH or MC units, for each depth, percentages from Table 1, Table 2 were converted to proportions and appropriate proportions were multiplied together resulting in Table 3a. For example, to obtain the contribution of CPMNs with superficial RFs to all DRG neurons, the following proportions are multiplied together: that of all DRG neurons that are C-nociceptors (1C/100 = 0.485), that of all C-nociceptors with superficial RFs (2C/100 = 0.177) and that of C-nociceptors with superficial RFs that are PMNs (3C/100 = 0.79). The product is multiplied by 100 to obtain the estimated percentage of all DRG neurons that are CPMNs with superficial RFs, that is, 6.8%.
Repeating this for units with dermal and deep RFs results in the total percentage contribution of all CPMNs to all L4/L5 DRG neurons, that is, 9.8%. Repeating these calculations for Aδ-PMNs and Aαβ-PMNs with RFs at these different depths and adding these to the CPMN total provides the cumulative percentage estimate of all PMNs to the whole DRG neuron population of 10.87% (Table 3a).
Table 3b repeats the above for heat-responsive nociceptors only (PMNs that are MH or MHC, but excluding MC). This is a smaller contribution, 6.8%, of all PMNs to all DRG neurons.
Thus, percentages for all CPMNs, just CMH + CMHC units and for just CMC units only are 9.8%, 6.8% and 3% (9.8 minus 6.8) respectively. Because more units were tested for noxious heat than noxious cold, the CMH + CMHC unit estimations of ∼7% are more reliable than the CPMNs, for which a range of 9-13% is a reasonable estimated range for all PMNs.
*indicates only 1-3 neurons tested with noxious thermal stimuli, and that had clear RF depth recorded, so less weight should be placed on these dermal and deep RF Aδ calculations.