Table 1.
Membrane potential (Em, mV) in parenchymal coleoptile cells. Data (mean ± SE) are mean values of at least seven independent experiments. Coleoptile segments were incubated in the indicated medium (the same as in growth experiments) for 110 min; afterwards a single segment was transferred into an electrophysiological chamber containing the same medium. Measurements of membrane potential (30 min) were carried out after insertion of a microelectrode into the cell and stabilization of the Em (<10 min) at 2 h (0 min, column A). Indole-3-acetic acid and FC were added after 2 h of segment incubation in the indicated medium; for the last 10 min before IAA or FC addition, coleoptile segments were incubated in the electrophysiological chamber. ns, Not statistically significant. *Statistically significant (P < 0.05).
| Treatment |
Membrane potential (mV) |
|||||||
|---|---|---|---|---|---|---|---|---|
| K+ | Ca2+ | A 0 min |
Transient depolarization | B 10 min |
C 20 min |
D 30 min |
ΔEm (D − A) (mV) | |
| (mM) |
||||||||
| IAA | 0.0 | 0.0 | −138.6 ± 7.1 | 1.4 | −138.2 ± 6.5 | −141.1 ± 7.6 | −141.2 ± 7.7 | −2.6ns |
| 0.1 | −136.5 ± 6.5 | 6.0 | −136.2 ± 7.3 | −151.5 ± 6.9 | −153.7 ± 6.8 | −17.2* | ||
| 1.0 | −134.1 ± 6.5 | 5.3 | −130.7 ± 6.1 | −140.8 ± 7.4 | −144.2 ± 7.0 | −10.1* | ||
| IAA | 1.0 | 0.0 | −124.5 ± 5.9 | 1.8 | −124.0 ± 6.2 | −126.5 ± 7.0 | −127.1 ± 6.8 | −2.6ns |
| 0.1 | −120.7 ± 6.1 | 5.5 | −118.3 ± 5.8 | −126.8 ± 6.7 | −129.3 ± 7.1 | −8.6* | ||
| 1.0 | −122.4 ± 6.3 | 7.3 | −116.3 ± 4.9 | −129.0 ± 7.2 | −132.4 ± 6.5 | −10.0* | ||
| IAA | 10 | 0.0 | −64.7 ± 5.0 | 1.5 | −64.5 ± 5.4 | −67.1 ± 3.9 | −67.4 ± 5.1 | −2.7ns |
| 0.1 | −65.6 ± 4.3 | 2.8 | −63.2 ± 5.0 | −69.6 ± 5.2 | −71.0 ± 4.7 | −5.4* | ||
| 1.0 | −64.8 ± 4.1 | 2.2 | −64.0 ± 4.7 | −70.3 ± 5.1 | −71.3 ± 4.3 | −6.5* | ||
| FC | 0.0 | 0.0 | −132.7 ± 7.1 | – | −139.0 ± 6.3 | −146.5 ± 6.9 | −146.6 ± 7.1 | −13.9* |
| 0.1 | −131.2 ± 6.6 | – | −140.8 ± 7.1 | −152.2 ± 7.3 | −155.8 ± 7.6 | −24.6* | ||
| 1.0 | −128.0 ± 7.2 | – | −142.1 ± 6.9 | −153.5 ± 7.9 | −155.4 ± 7.9 | −27.4* | ||
| FC | 1.0 | 0.0 | −120.1 ± 5.8 | – | −125.5 ± 6.2 | −128.1 ± 6.5 | −128.0 ± 6.1 | −7.9* |
| 0.1 | −118.7 ± 5.5 | – | −126.7 ± 6.6 | −135.8 ± 6.4 | −138.4 ± 7.2 | −19.7* | ||
| 1.0 | −121.3 ± 6.1 | – | −128.0 ± 6.4 | −135.0 ± 7.2 | −135.9 ± 6.3 | −14.6* | ||
| FC | 10 | 0.0 | −65.5 ± 4.2 | – | −66.9 ± 3.9 | −69.2 ± 5.1 | −69.5 ± 4.1 | −4.0ns |
| 0.1 | −68.4 ± 4.7 | – | −75.2 ± 4.6 | −78.5 ± 4.8 | −81.3 ± 5.3 | −12.9* | ||
| 1.0 | −64.6 ± 4.6 | – | −71.0 ± 5.1 | −75.7 ± 4.9 | −77.3 ± 4.8 | −12.7* | ||