O2k signals and output

Signals of the O2k-Core and add-on modules

Three electronic channel types are available in the O2k-MultiSensor system. All channels are available twofold (dual-data), for O2k-Chambers A and B (left and right), based on signals (numerical) sent at a fixed data sampling time interval (typical: 1 s or 2 s; range 0.2 s to >10 s):

1. O₂ channel with electric current (ampere [Amp]) as the primary signal, which is converted to a voltage (volt [V]) as the raw signal. The O2k-Core supports not only the O₂ channel (O2 plug), but also the channel types 2 and 3 for the add-on modules.

2. Amp channel: The amperometric channel of the O2k (Amp plug), has electric current (ampere [Amp]) as the primary signal, which is converted to a voltage (volt [V]) as the raw signal. The Amp-Channel is used with the O2k-Fluo LED2-Module and the O2k-NO Amp-Module.

3. pX channel with electric potential (volt [V]) as the primary and raw signal (BNC pX plug for the ion sensitive electrode, ISE; and separate plug for the pX reference electrode, Ref).

System channels, for instrumental control, not separated into O2k-Chamber A and B (single-data), based on signals (numerical) sent at the same fixed data sampling time interval:

4a. Block temperature: Measured block temperature equivalent to the experimental temperature in the O2k-Chambers at steady state [°C].

4b. Peltier power (system channel): Relative heating or cooling power of the Peltier system.

4c. Barometric pressure (system channel): Measured barometric pressure [kPa].

4d. Ambient temperature (system channel): Measured temperature of room air (O2k-Series G upwards) [°C].

4d. External temperature (system channel): Temperature measured with an independently placed thermistor (O2k-Series G upwards) [°C].

Events carry information on a time point during the experiment, a short event name (text), and a longer string of comments (text):

5. Events: Automatic events (e.g. from the TIP2k) and manually triggered events.

NextGen-O2k: additional channel types are available in the NextGen-O2k:

6. Dual-fluo channel.

7. Spectrophotometric channel.

O2k output

The 'output' of a channel is the finally important infomation, which may be summarized in a data base. Three types of output can be derived from the signal of the O2k channels:

I: Concentration. Examples: O₂; Ca²⁺; amount of substrance per volume [1 µM = 1 µmol·dm^-3 = 1 nmol·ml^-1].

II: Flow, flux, rate. Examples: O₂ consumption; H₂O₂ production; volume-specific flux is the negative or positive time derivative of concentration over time, frequently multiplied by 1,000 [pmol·s^-1·ml^-1]. Volume-specific flux normalized for the cell density [10⁶·ml^-1] is flow [pmol·s^-1·ml^-1]. Volume-specific flux normalized for the mass density of the sample in the O2k-Chamber [mg·ml^-1] is mass-specific flux [pmol·s^-1·mg^-1]. Flux in any respiratory state normalized for flux in a defined reference state is a rate [dimensionless] or flux control ratio.

III: Force, potential (e.g. TMRM and Safranin for mt-membrane potential; redox potential from cytochrome or NADH redox states).

IV: Pre-calibrated signals for system channels.

V: Events.

1. O₂ channel - O2k-Core: Output type I and II.

2a. Amp channel - O2k-Fluo LED2-Module: The focus of the output depends on the specific fluorophore. Output type I, II, or III, or any combination may relate to the primary level of interest.

2b. Amp channel - O2k-NO Amp-Module: Output type I and II.

3a. pX channel - O2k-TPP+ ISE-Module: Output type III.

3b. pX channel - O2k-pH ISE-Module: Output type I and II.

4. Events - O2k-Core and TIP2k

6. Single-fluo channel - NextGen-O2k: Plots of one selected wavelength can be selected for recording. Output type I(1), II(1), III(1) depends on the fluorophore.

7. Dual-fluo channel - NextGen-O2k: Plots of two selected wavelengths can be selected for simultaneous recording. Output type I(2), II(2), III(2) depends on the fluorophore.

8. Spectrophotometric channel - NextGen-O2k: Output type VI (three plots for redox states of cytochromes aa₃, b, and c.