Table 2.
Effect of necleotides on cation channel Po and block of the effect
| Condition | n (N) | Po control | Po nucleotide | Po wash | |
|---|---|---|---|---|---|
| Nucleotides | mM | ||||
| ATP | 0.25-3 | 24 (39) | 0.028 ± 0.007 | 0.184 ± 0.047 | |
| ADP | 1 | 5 (8) | 0.003 ± 0.001 | 0.005 ± 0.002 | |
| AMP | 1 | 4 (4) | 0.006 ± 0.005 | 0.006 ± 0.002 | |
| AMP-PNP | 1 | 3 (8) | 0.042 ± 0.017 | 0.035 ± 0.024 | |
| ATPγS | 1 | 4 (8) | 0.005 ± 0.003 | 0.020 ± 0.010 | |
| 3 | 1 (8) | 0.033 | 0.511 | ||
| Inhibitors | μM | ATP | |||
| H7 | 100 | 4 | 0.040 ± 0.010 | 0.017 ± 0.007 | |
| PKC (19-36) | 5 | 3 | 0.023 ± 0.005 | 0.018 ± 0.007 | |
| PKC (19-36) | 20 | 5 | 0.032 ± 0.015 | 0.026 ± 0.008 | |
| PKA (6-22) | 1 | 5 | 0.009 ± 0.004 | 0.075 ± 0.021 | |
| Control | - | 6 (9) | 0.053 ± 0.029 | 0.168 ± 0.086 | 0.038 ± 0.020 |
| Microcystin | 0.010 | 3 (4) | 0.001 ± 0.000 | 0.012 ± 0.001 | 0.004 ± 0.001 |
| Microcystin | 0.200 | 4 | 0.007 ± 0.002 | 0.019 ± 0.005 | 0.016 ± 0.004 |
The values given are the average Po values (± S.E.M) obtained before and after application of each nucleotide at the concentrations indicated. Inhibitors were present for all conditions (control, ATP, and wash). The concentration of ATP used with kinase inhibitors was 1 mM; the concentration of ATP used with phosphatase inhibitors was 2 mM. n is the number of patches contributing to each determination of Po; the N given in parenthesis is the number of patches for which qualitatively similar results were obtained regardless of the number of channels present and at concentrations ranging from 1 to 3 mM, except in the case of ATP in which the concentration ranged from 0.25 to 5 mM. Po determinations were limited to patches containing from 1 to 3 channels (see Materials and Methods).