Biology Reference
In-Depth Information
3. The pump is responsible to provide, at a constant and precise
flow rate, the air mixture from the ambient air or gas cylinder(s)
to the plethysmography chamber. There is a wide range of
quality in the commercially available pumps, the main differ-
ences between them being the flow regulation. These param-
eters are very important to prevent any accumulation of CO
2
and evaporated water inside the chamber and to minimize the
interaction of the provided air with the animal's breathing pat-
tern. The importance of the latter is increasing while the size
of the tested animal is decreasing, becoming crucial in plethys-
mography experiments carried out on neonatal mice.
4. The flow meter is a device that directly and precisely measures,
in a real-time manner, the flow of the air entering in the plethys-
mography chamber. It should be installed just before the arrival
of the air to the chamber, in order to take into account all
eventual air resistance upstream to the chamber. A precise flow
meter is essential to a rigorous plethysmography system since it
should provide an exact evaluation of the air flow the mice is
exposed to, as well as a way to verify a constant flow in order to
minimize the interaction with the animal's breathing pattern
registered.
5. The ambient temperature in the plethysmography chamber
should be monitored in order to make corrections for STPD
conditions in the calculation of O
2
consumption and CO
2
pro-
duction by the mice (cf. Subheading
3.5
, steps 4 and 5).
6. The differential pressure transducer is a small device connected
directly to the plethysmography chamber with one port
exposed to the animal chamber and another one exposed to
the reference chamber which is empty and subjected to the
atmospheric pressure. Thanks to this configuration, the trans-
ducer can measure the pressure fluctuations within the plethys-
mography chamber which results from mice breathing.
7. The pressure odf the evaporated water in the plethysmogra-
phy chamber should be monitored in order to make correc-
tions for BTPS conditions in the calculation of
V
T
(cf. Subheading
3.5
, step 2).
8. The subsampling pump helps to avoid the generation of a
positive pressure within the plethysmography chamber and,
most importantly, it allows obtaining the air composition
before being modified by the animal breathing inside the
chamber (Fig.
1
). This subsampled air is essential to deter-
mine
V
V
O
(cf. Subheading
3.5
, step 4) and
CO
(cf.
2
2
Subheading
3.5
, step 5).
9. A data acquisition system is necessary to receive analog data
(electrical signals) from the measurements devices (flow meter,
thermometer, amplifier of pressure transducer, humidity meter,
Search WWH ::
Custom Search