Table 2.
ATP release in C6 cells overexpressing Cx43, Cx32, or null-transfected controls
| Compounds/conditions | Cx43+ cells | Cx32+ cells | Control cells |
|---|---|---|---|
| Purinergic receptor antagonism | |||
| Suramin (100 μM) | BD | BD | BD |
| Reactive blue (30 μM) | BD | BD | BD |
| PPADS (50 μM) | 121 ± 14 | 105 ± 7 | 89 ± 17 |
| Elevation of Ca2+i | |||
| Ca2+-ionophore (40 μM) | 22 ± 3* | 21 ± 8* | 27 ± 12* |
| Bradykinin (25 μM) | 18 ± 5* | 24 ± 13* | 29 ± 4* |
| Endothelin (0.1 μM) | 16 ± 9* | 11 ± 7* | 14 ± 5* |
| Ionic composition | |||
| Cl−-free (gluconate substitute) | 3380 ± 1600* | 1530 ± 700* | 148 ± 17* |
| Na+-free (choline substitute) | 100 ± 15 | 63 ± 4* | 77 ± 23 |
| Ca2+-free | 1280 ± 390* | 870 ± 117* | 139 ± 15 |
| High K+ (100 mM) | 97 ± 10 | 132 ± 17 | 107 ± 9 |
| Hypoosmotic (220 mOs) | 173 ± 19* | 192 ± 17* | 147 ± 11* |
| Hyperosmotic (420 Osm) | 103 ± 12 | 108 ± 1 | 108 ± 14 |
| Ca2+ signaling inhibition | |||
| Thapsigargin, pretreatment (4 μM) | BD | BD | BD |
| BAPTA (10 μM) | 11 ± 7* | 27 ± 12* | BD |
| Cl− channel or transport inhibition† | |||
| SITS (3 mM) | 10 ± 2* | 1 ± 1* | BD |
| NPPB (100 μM) | 31 ± 5* | 30 ± 8* | BD |
| Furosemide (5 mM) | 25 ± 11* | 28 ± 13* | BD |
| Vesicular release | |||
| Latrotoxin (3 nM) | 2 ± 3* | 5 ± 6* | BD |
The fractional change in ATP release was calculated as the mean of ATP released in presence of compounds divided by the mean of ATP in matched cultures (Cx43, Cx32, or control) exposed to vehicle (mean ± SEM). BD, ATP release below detection. SITS, 4-acetamido-4′-isothiocyanatostilbene-2,2′-disulfonic acid; PPADS, pyridoxal phosphate-6-azophenyl-2′,4′-disulfonic acid tetrasodium; NPPB, 5-nitro-2-(3-phenylpropylamino)benzoic acid; BAPTA, 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetate.
*
Significant difference from control at P < 0.05 by t test; n = 8–35.