Table II.
Modulation of Cyclic Nucleotide-gated Nucleotide-gated Currents in Membrane Patches of Rods and Cone * ‡
| Cone | Rod | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| K 1/2 | n | N | K 1/2 | n | N | |||||||
| cGMP | μM | μM | ||||||||||
| Before exposure to EDTA/EGTA solution | 86.1 ± 18 | 2.57 ± 0.34 | 8 | 41.1 ± 7 | 2.58 ± 0.43 | 9 | ||||||
| After exposure to EDTA/EGTA solution | 58.85 ± 19.3 | 1.8 ± 0.23 | 8 | 27.5 ± 6.2 | 1.97 ± 0.28 | 9 | ||||||
| With added calmodulin (200 nM) | 70.4 ± 17.5 | 2.1 ± 0.25 | 8 | 37.3 ± 8.8 | 2.44 ± 0.48 | 9 | ||||||
| 8-Br-cGMP | ||||||||||||
| Before exposure to EDTA/EGTA solution | 22.1 ± 3.1 | 2.29 ± 0.39 | 6 | |||||||||
| After exposure to EDTA/EGTA solution | 16.4 ± 3.8 | 1.54 ± 0.35 | 6 | |||||||||
*
Under all test conditions, currents were measured in the presence of 20 μM Ca++ and 100 μM Mg++.
‡
The means under all conditions tested are statistically different from each other, with P < 0.02 as determined by a one-tail Student t test. The data for cGMP activation under the three experimental conditions specified were all measured in the same set of eight membrane patches.