Table 5. Membrane potential (ΔΨ), pH gradient (ΔpH) and proton motive force (Δp) quantitation in malate-grown P. denitrificans cells in the presence of 10 μM venturicidin.
| Experimental condition | ΔΨ (mV) | ΔpH (mV) | Δp (mV) | Respiration rate (mol O2/min/mol cyt aa3) |
|---|---|---|---|---|
| No addition | -130 ± 3.4 | -15.4 ± 2.6 | -145.3 ± 7.6 | 167.5 ± 17 |
| + Venturicidin | -156.9 ± 2.4 | -7.9 ± 3.4 | -164.8 ± 5.1 | 152 ± 4.6 |
| + Malate | -163.1 ± 2.3 | -7.4 ± 3 | -170.5 ± 3.6 | 311.9 ± 12.6 |
| + KCl (first phase)a (second phase)b |
-142 ± 1.6 | -21.4 ± 3 | -163.5 ± 1.8 | 721.2 ± 36.4 |
| -151.4 ± 1.9 | -11.3 ± 4 | -162.6 ± 1.5 | 453.1 ± 24.3 | |
| Hypoxia | -131.6 ± 2.9 | 17.9 ± 3.9 | -113.7 ± 5.6 | 0 ± 0 |
| + Nigericin | -99.7 ± 6.5 | 3.3 ± 1.4 | -96.4 ± 7.7 | 0 ± 0 |
Mean ± SE of 6 (ΔΨ and respiration rate) or 3 (ΔpH and Δp) independent determinations. Reagents were sequentially added as shown in Fig 6. Δp was not statistically different between the + Malate and the + KCl conditions (p = 0.13) according to a paired t-test.
aThe first phase corresponds to the average of the first 2 min after KCl addition.
bValues for the second phase correspond to the average between 4 min after KCl addition and just before hypoxia.