Modulation of nicotinic receptor sensitivity by varying agonist concentrations
| S1 | S2 | [Ca2+]i | Control |
|---|---|---|---|
| m | nm | % | |
| No drug | 3 × 10−6DMPP | 37 ± 7 | 100 |
| Subthreshold DMPP | 3 × 10−6 DMPP | 65 ± 6** | 175 |
| No drug | 1 × 10−5 DMPP | 51 ± 7 | 100 |
| Subthreshold DMPP | 1 × 10−5 DMPP | 78 ± 6* | 153 |
Dispersed cells (1–2 × 106) were exposed to subthreshold concentrations (S1) of DMPP (10−7m or 3 × 10−7m) followed 40 sec later by exposure (S2) to a half-maximal (3 × 10−6m) or maximal concentration of agonist (10−5m). The values represent the mean ± standard error of 8 to 20 determinations from two to five experiments. Significance of difference from control:*p < 0.01; **p < 0.001.