Depletion of the SR does not reduce the [Ca2+] increases in subplasma membrane space or bulk cytoplasm
| Control | Peak [Ca2+] (ΔF/F0) | Rise time (ms) | Rise slope (ΔF/F0/s) | Decay time (ms) | Decay slope (ΔF/F0/s) | n | |
| Subplasma membrane space | Average | 4.7 ± 1.2 | 312 ± 55 | 10.0 ± 5.1 | 3,236 ± 1,705 | −2.0 ± 0.7 | 4 |
| Regions | 6.2 ± 1.0 | 145 ± 30 | 31 ± 9.2 | 1,136 ± 221 | −3.8 ± 0.7 | 8 | |
| Bulk cytoplasm | Average | 5.1 ± 0.9 | 328 ± 55 | 10.7 ± 3.0 | 3,295 ± 1,759 | −2.1 ± 0.7 | 4 |
| Regions | 5.3 ± 0.7 | 320 ± 59 | 13 ± 3.4 | 3,187 ± 1,116 | −2.3 ± 0.7 | 8 | |
| After SR depletion | |||||||
| Subplasma membrane space | Average | 5.1 ± 0.8 | 365 ± 84 | 11.6 ± 2.5 | 3,708 ± 2,290 | −1.7 ± 0.6 | 4 |
| Regions | 6.6 ± 0.7 | 133 ± 41 | 30 ± 7.7 | 1,040 ± 151 | −3.1 ± 0.5 | 8 | |
| Bulk cytoplasm | Average | 6.6 ± 1.6 | 372 ± 50 | 12.3 ± 1.2 | 3,868 ± 1,934 | −1.9 ± 0.4 | 4 |
| Regions | 6.8 ± 1.4 | 472 ± 152 | 19 ± 7.0 | 2,129 ± 496 | −2.7 ± 0.9 | 8 |
| Control | Peak [Ca2+] (ΔF/F0) | Rise time (ms) | Rise slope (ΔF/F0/s) | Decay time (ms) | Decay slope (ΔF/F0/s) | n | |
| Subplasma membrane space | Average | 4.7 ± 1.2 | 312 ± 55 | 10.0 ± 5.1 | 3,236 ± 1,705 | −2.0 ± 0.7 | 4 |
| Regions | 6.2 ± 1.0 | 145 ± 30 | 31 ± 9.2 | 1,136 ± 221 | −3.8 ± 0.7 | 8 | |
| Bulk cytoplasm | Average | 5.1 ± 0.9 | 328 ± 55 | 10.7 ± 3.0 | 3,295 ± 1,759 | −2.1 ± 0.7 | 4 |
| Regions | 5.3 ± 0.7 | 320 ± 59 | 13 ± 3.4 | 3,187 ± 1,116 | −2.3 ± 0.7 | 8 | |
| After SR depletion | |||||||
| Subplasma membrane space | Average | 5.1 ± 0.8 | 365 ± 84 | 11.6 ± 2.5 | 3,708 ± 2,290 | −1.7 ± 0.6 | 4 |
| Regions | 6.6 ± 0.7 | 133 ± 41 | 30 ± 7.7 | 1,040 ± 151 | −3.1 ± 0.5 | 8 | |
| Bulk cytoplasm | Average | 6.6 ± 1.6 | 372 ± 50 | 12.3 ± 1.2 | 3,868 ± 1,934 | −1.9 ± 0.4 | 4 |
| Regions | 6.8 ± 1.4 | 472 ± 152 | 19 ± 7.0 | 2,129 ± 496 | −2.7 ± 0.9 | 8 |
SR depletion (using 50 µM ryanodine and repetitive application of 10 mM caffeine) neither reduced the depolarization-evoked [Ca2+]PM or [Ca2+]c increase. This result suggests that SR Ca2+ release does not contribute substantially to the depolarization-evoked [Ca2+]PM or [Ca2+]c increases. The rise time, rise slope, decay time, and decay slope were measured from the changes that occurred between 20 and 80% of the peak ΔF/F0 values. The “average” value has been derived from the entire region that was visible in TIRF. That area was used to generate an “area of interest,” which was applied to obtain the average change that occurred in the bulk cytoplasm as measured in wide-field epifluorescence. “Regions” were 1-pixel areas.