Biology Reference
In-Depth Information
Fig. 3. Photomicrograph showing the well before (
a
) and after (
b
) the soft wax is put
above the recording site.
(g) Soft paraffi n wax:
Soft paraffi n wax is used to cover the brain surface after
placing the recording electrode into the recording area.
Surface soft wax protects the brain from desiccation and
reduce the brain pulsation. Soft paraffi n wax is prepared by
mixing the solid paraffi n prills (J.T. Baker) and mineral oil
(Fisher Scientifi c, Hanover Park, IL) in proportion (start
with 50 vs. 50%). The fi nal product should be in the solid
phase at room temperature (24°C) and in the liquid phase
at ~40°C. So we can pour the wax into the well to cover the
brain without hurting the brain tissue due to the heat
(Fig.
3
).
(h) Anesthesia:
For general anesthesia, urethane (1.25 g/kg, i.p.) is used.
Supplemental doses of ketamine and xylazine mixture
(10 mg/kg, i.m.) are used once per hour as needed. If the
possible side effects of ketamine on glutamate receptors are
the concern, 1-2% isofl urane mixture with 33% oxygen and
66% nitrogen is a good agent for anesthesia. Another advan-
tage of using isofl urane is that the animals recover from
anesthesia minutes after turning off the isofl urane supply.
1.3. Procedures
1. Preparing electrodes.
2. Recording electrodes:
Preparation of recording electrode is critical for successful
intracellular recording in vivo. Recording electrode is pulled
from a Borosilicate glass tubing with fi lament (2.0 × 1.16 mm,
4
, A-M systems) with Kopf 750 vertical electrode puller.
Carefully adjust the parameters of Heat 1, Solenoid current
and Delay time to obtain an electrode with the smooth taper
and shank. The most important part is to obtain a small tip with
a diameter of 0.2-0.5 mm. Because it is diffi cult to measure
the diameter, the measurement of electrode tip resistance is a
good way to evaluate the size of the electrode tip. Normally, a
resistance of 40-100 MW with the electrode solution of 2 M
″
Search WWH ::
Custom Search