132
2 Holographic Microscopy of Phase and Diffuse Objects …
placed. The thickness of the rubber gasket was selected in such a way that the gap
between the upper optical camera glass and the prism was no more than 1–1.5 mm.
Then, in the closed camera spreading between the prism and the upper optical
window, the physiological solution formed a plane-parallel capillary layer that was
a necessary condition to conduct interference measurements. While conducting the
electrophysiological studies of the nerve fiber such a construction of the camera
made it possible to stimulate and derivate the action potential using Tasaki air bridges
method [292, 374] (Fig. 2.28b).
In the lower camera disk, three channels with the diameter of 1 mm were turned
to supply stimulating and pickup electrodes and making gas pressure in the working
volume of the camera. To seal the the camera the holes, through which the electrodes
were extended, were coated with epoxy adhesive, and lead gaskets were used in the
pressure gas pipe. When the camera in a working mode was installed into the unit,
it was pressed using two screws between two metal plates with holes, which open
optical windows.
The gas pressure in the camera in the range of 0–5 atm. was produced with the help
of the compressor UK40-2M. The release valve of the compressor made it possible
to adjust pressure and its speed. To eliminate possible measurement errors using the
real-time holographic interference method, there was conducted the study of active
volume deformations in the gas camera under pressure.
A series of experiments were conducted on recording differential holographic
interferograms of the nerve fiber under gas pressure of 4 atm. When the measurement
accuracy of insertion phase incursion is λ/30 (λ = 632.8 nm), the optical characteristics stability was shown of the refraction index of isolated nerve and muscle fibers.
It was ascertained that phase incursion alteration carried in by the nerve fiber under
hyperbary does not exceed 0.2 rad. When studying solitary muscle fiber contraction
using the laser diffractometry method, in some experiments, it was found that high
gas pressure (4 atm.) influences fiber excitability threshold.
As a main index of vital functions in the nerve tissue, the excitability parameters
were used in response to electric stimulation. Solitary nerve and muscle fibers as
well as nerve fibers as a part of an isolated nerve were the object of the study.
Preparation methods. The isolated nerve preparation was obtained by extraction
of the sciatic nerve of a frog cutting it higher and lower of the applied ligatures which
were used in a case of necessity for fixing and transferring it to special cameras. On
the extraction stage and in further studies, the preparation was moistened with a
physiological solution (0.9% NaCl) or with Ringer solution (NaCl—110.5; KCl—
2.5; CaCl 2 1.8; Tris—5.0 mmol, pH—7.3) to avoid extinction. The preparations were
placed in the same medium during the whole period of registration.
The solitary isolated nerve fibers were dissected from the sciatic nerve of a frog.
For this purposes, the isolated nerve was placed on the stage of binocular microscope
MBS-9 in a drop of the physiological solution. The object was examined for transparency. Optical fibered illuminator OVS-I was used for this purpose. That allowed
eliminating overheating of the object during lightning up and decelerating evaporation of water from the physiological solution. Then, all the preparation operations
2 Holographic Microscopy of Phase and Diffuse Objects …
placed. The thickness of the rubber gasket was selected in such a way that the gap
between the upper optical camera glass and the prism was no more than 1–1.5 mm.
Then, in the closed camera spreading between the prism and the upper optical
window, the physiological solution formed a plane-parallel capillary layer that was
a necessary condition to conduct interference measurements. While conducting the
electrophysiological studies of the nerve fiber such a construction of the camera
made it possible to stimulate and derivate the action potential using Tasaki air bridges
method [292, 374] (Fig. 2.28b).
In the lower camera disk, three channels with the diameter of 1 mm were turned
to supply stimulating and pickup electrodes and making gas pressure in the working
volume of the camera. To seal the the camera the holes, through which the electrodes
were extended, were coated with epoxy adhesive, and lead gaskets were used in the
pressure gas pipe. When the camera in a working mode was installed into the unit,
it was pressed using two screws between two metal plates with holes, which open
optical windows.
The gas pressure in the camera in the range of 0–5 atm. was produced with the help
of the compressor UK40-2M. The release valve of the compressor made it possible
to adjust pressure and its speed. To eliminate possible measurement errors using the
real-time holographic interference method, there was conducted the study of active
volume deformations in the gas camera under pressure.
A series of experiments were conducted on recording differential holographic
interferograms of the nerve fiber under gas pressure of 4 atm. When the measurement
accuracy of insertion phase incursion is λ/30 (λ = 632.8 nm), the optical characteristics stability was shown of the refraction index of isolated nerve and muscle fibers.
It was ascertained that phase incursion alteration carried in by the nerve fiber under
hyperbary does not exceed 0.2 rad. When studying solitary muscle fiber contraction
using the laser diffractometry method, in some experiments, it was found that high
gas pressure (4 atm.) influences fiber excitability threshold.
As a main index of vital functions in the nerve tissue, the excitability parameters
were used in response to electric stimulation. Solitary nerve and muscle fibers as
well as nerve fibers as a part of an isolated nerve were the object of the study.
Preparation methods. The isolated nerve preparation was obtained by extraction
of the sciatic nerve of a frog cutting it higher and lower of the applied ligatures which
were used in a case of necessity for fixing and transferring it to special cameras. On
the extraction stage and in further studies, the preparation was moistened with a
physiological solution (0.9% NaCl) or with Ringer solution (NaCl—110.5; KCl—
2.5; CaCl 2 1.8; Tris—5.0 mmol, pH—7.3) to avoid extinction. The preparations were
placed in the same medium during the whole period of registration.
The solitary isolated nerve fibers were dissected from the sciatic nerve of a frog.
For this purposes, the isolated nerve was placed on the stage of binocular microscope
MBS-9 in a drop of the physiological solution. The object was examined for transparency. Optical fibered illuminator OVS-I was used for this purpose. That allowed
eliminating overheating of the object during lightning up and decelerating evaporation of water from the physiological solution. Then, all the preparation operations