Table 1: Spark parameters for 8 fibres examined.

1. Fig 1: Rise time vs. amplitude of sparks recorded initially in glutamate (black, filled circles), sulphate (red) and upon return to glutamate solution (black, open circles). Results is from 8 fibres. Table 1: Spark parameters for 8 fibres examined.

2. Glut SO42- Glut SR [Ca2+] (μM) Spark frequency (100 μm s-1)-1 Time (min) Fig 1: Ca2+ spark freq and [Ca2+]SR in a frog skeletal muscle fibre exposed to a sequence of glutamate, sulphate, glutamate. [Ca2+]cyto and [Mg2+]cyto where 100 nM and 0.4 mM, respectively, throughout. Note the significant increase in [Ca2+]SR upon removal of sulphate, ‘Ca2+ surge’. SR [Ca2+] recalculated on 19 Nov ‘04 033004a

3. 50 mM EGTA (0 Ca) SR [Ca2+] (μM) Glut 20mM Pi EGTA SR [Ca2+] (μM) Fig 7: Precipitation of Ca2+ in the SR in the presence of 20 mM cytoplasmic Pi, 100 nM Ca2+. Note that [Ca2+]SR increases in Pi, yet the Ca2+ surge in 50 mM EGTA still shows precipitation/continuous loading must have occurred in Pi (cf Fig 2). 113004b

4. expt 102804a SO4 RATIO time, s

7. Fig 1. Spark frequency in chemically-permeabilized frog fibres upon changing the cytoplasmic anion from glutamate to sulphate and back to glutamate, in the constant presence of 100 nM Ca2+ and 0.4 mM Mg2+. The spark frequency represented is the frequency/100 µm of fibre in linescan/block of 20 linescans. The final result was obtained from equally weighted averages of the 12 fibres examined.

9. Fig 2: Average amplitude (A) and average width (B) of sparks in chemically-permeabilized frog fibres upon changing the cytoplasmic anion from glutamate to sulphate and back to glutamate, in the constant presence of 100 nM Ca2+ and 0.4 mM Mg2+. Results is from 9 fibres, equally weighted.

10. Fig 3: “Sulphaticity”: width/amplitude of sparks in chemically-permeabilized frog fibres upon changing the cytoplasmic anion from glutamate to sulphate and back to glutamate, in the constant presence of 100 nM Ca2+ and 0.4 mM Mg2+. Result is from 9 fibres.

11. SO42-, 200 Ca Glut, 200 Ca Glut, 200 Ca The first experiment with BTS stopping the contracture upon SO42- removal. 010504b

12. Glut, 200 Ca SO42-, 200 Ca Glut, 200 Ca Poorly loaded cell—looks to be mitochondria loaded 010504c

13. Glut SO42- Glut SO42- Glut G 012204a 30 mM caff, 1 mM EGTA, 0.01 mM Mg2+.

14. 012204b/ 020404a?

15. Glut SO42- Glut log.SR [Ca2+] (mM) Spark frequency (100 μm s-1)-1 Glut, 0.4mM Mg2+, 100nM Ca2+. SO42-, 0.4mM Mg2+, 100nM Ca2+. Glut, 0.4mM Mg2+, 100nM Ca2+. SR [Ca2+] recalculated on 22 Nov ‘04 031204c

16. Glut SO42- Glut SR [Ca2+] (μM) Spark frequency (100 μm s-1)-1 Time (min) SR [Ca2+] recalculated on 19 Nov ‘04 033004a

17. Launikonis et al. fig. 1 A B C b c a

19. Glut SO42- Glut SR [Ca2+] recalculated on 22 Nov ‘04 1st image in this series is in Glut, 0 Ca, 0 Mg, 0 ATP solution. Glut, 0.4mM Mg2+, 100nM Ca2+. SO42-, 0.4mM Mg2+, 100nM Ca2+. Glut, 0.4mM Mg2+, 100nM Ca2+. 033004b

20. Glut Glut SO42- 033104a SR [Ca2+] recalculated on 22 Nov ‘04

21. Glut SO42- Glut SR [Ca2+] recalculated on 22 Nov ‘04 041204a

22. Glut SO42- Glut SR [Ca2+] recalculated on 22 Nov ‘04 041204b

23. * 50 mM EGTA (< 1 nM Ca2+) & 1 mM Mg2+. Glut SO42- EGTA SR [Ca2+] recalculated on 22 Nov ‘04 060204a Very well loaded cell.

24. Glut SO42- Glut SR [Ca2+] recalculated on 22 Nov ‘04 Lost last SR [Ca2+] reading after final set of 50 XT’s. 081004a

25. Glut SO42- Glut 400 Ca 100 Ca SR [Ca2+] recalculated on 22 Nov ‘04 081004b

26. SO42- was only applied for 1 min Glut Glut SR [Ca2+] (µM) 060704a

27. Glut, 1mM Mg2+, 200nM Ca2+. 50mM Pi, 1mM Mg2+, 200nM Ca2+. Edge Glut, 1mM Mg2+, 200nM Ca2+. Middle Glut, 1mM Mg, 200 Ca 50 Pi, 200 Ca, 1 Mg Glut, 1 Mg, 200 Ca SR [Ca2+] (μM) 011604a

29. R, [Ca2+]SR, mM

30. 40 mM citrate, 100 nM Ca2+, 0.4 mM Mg2+ Glut Glut Fig 9: 40 mM citrate causes a small change in [Ca2+]SR when substituted for glutamate. There is no Ca2+ surge upon removal of citrate, suggesting there was no precipitation of Ca2+inside the SR. 051905a_s015-024