| . | 1 mM glucose . | 10 mM glucose . | 0.2 mM tolbutamide . | ||||||
|---|---|---|---|---|---|---|---|---|---|
| . | Vm (mV) . | Vpeak (mV) . | Frequency (Hz) . | Vm (mV) . | Vpeak (mV) . | Frequency (Hz) . | Vm (mV) . | Vpeak (mV) . | Frequency (Hz) . |
| NMRI (n = 6) | −71 ± 3 | n/a | n/a | −54 ± 3a | 6 ± 4 | 0.6 ± 0.2 | −48 ± 3b | 4 ± 3b | 0.6 ± 0.1 |
| SST-tdRFP (n = 3) | −74 ± 4 | n/a | n/a | −62 ± 2a | 14 ± 8 | 0.2 ± 0.2 | −54 ± 3b | 3 ± 3b | 0.3 ± 02 |
| SST-GCaMP3 (n = 4) | −73 ± 3 | n/a | n/a | −54 ± 3a | 25 ± 8 | 0.6 ± 0.3 | −37 ± 2b | 8 ± 4b | 0.4 ± 0.3 |
| . | 1 mM glucose . | 10 mM glucose . | 0.2 mM tolbutamide . | ||||||
|---|---|---|---|---|---|---|---|---|---|
| . | Vm (mV) . | Vpeak (mV) . | Frequency (Hz) . | Vm (mV) . | Vpeak (mV) . | Frequency (Hz) . | Vm (mV) . | Vpeak (mV) . | Frequency (Hz) . |
| NMRI (n = 6) | −71 ± 3 | n/a | n/a | −54 ± 3a | 6 ± 4 | 0.6 ± 0.2 | −48 ± 3b | 4 ± 3b | 0.6 ± 0.1 |
| SST-tdRFP (n = 3) | −74 ± 4 | n/a | n/a | −62 ± 2a | 14 ± 8 | 0.2 ± 0.2 | −54 ± 3b | 3 ± 3b | 0.3 ± 02 |
| SST-GCaMP3 (n = 4) | −73 ± 3 | n/a | n/a | −54 ± 3a | 25 ± 8 | 0.6 ± 0.3 | −37 ± 2b | 8 ± 4b | 0.4 ± 0.3 |
Electrical activity recorded from δ-cells in intact islets isolated from NMRI, SST-tdRFP, and SST-GCaMP3 mice. Membrane potential (Vm), Vpeak, and firing frequency of action potentials when δ-cells were exposed to 1 mM glucose, 10 mM glucose, or 200 µM tolbutamide are summarized and compared between different mouse strains. Data are presented as mean values ± SEM of indicated number of independent experiments (n) from three to five animals. No action potential was detected at 1 mM glucose in all groups. Therefore the data for Vpeak and Frequency at 1 mM glucose are shown as n/a (not available). There were no statistical differences between the different mouse models. All the measurements were made using perforated patch clamping technique.
P < 0.05 vs. 1 mM glucose (for each model).
P < 0.05 vs. 20 mM glucose (for each model).