2.3 Holographic Study with Electrophysiological Control …
133
with the solitary nerve fiber were conducted according to the methods, described by
I. Tasaki [292, 374].
Methods of estimating the excitability. The excitability of the isolated solitary
nerve fiber was estimated according to the presence of action potential, the disappearance of which under continuous stimulation was considered as an irreversible
injury of the nerve fiber. The excitability of the nerve fiber as a part of isolated nerve
trunk was estimated according to the duration amplitude of the total action potential.
In a series of cases, such characteristics were recorded as excitability of the isolated
nerve, threshold value of electrical stimulation voltage with different duration of an
electric pulse (50, 100, 200 μs), to construct a graph duration-force. The excitability
of an isolated muscle fiber was estimated according to the presence of contraction in
response to electrostimulation and threshold (minimal) quantity of the voltage which
caused the contraction. An electromyograph produced by firm “Medicor” was used
for objects stimulation, amplification and observation of the action potentials.
To record the action potentials and isolated solitary nerve fibers stimulation, metal
electrodes were used which were placed inside the camera to investigate in such a
way that a simultaneous electrophysiological control is carried out during optical
measurements (see Fig. 2.14).
Results of the study. During electrophysiological control of vital functions of
the solitary nerve fibers, the attention was drawn to the irreversible suppression of
generation of action potential in the first seconds of high air pressure application. An
electrophysiological study of the isolated nerve was conducted to make sure whether
hyperbary is the reason of suppression of the ability of the nerve fiber to react with
action potential in response to electrical stimulation or whether it is a consequence of
mechanical injuries during preparing of solitary nerve fibers which often accompany
it.
Isolated sciatic nerves of a brown frog were object to the study. The total action
potential of the nerve fibers was analyzed in response to electrostimulation at the
frequency of 50 Hz during and after the high air pressure application (1 or 2 atm.).
The graphs illustrating statistically correct electrical stimulation voltage increase
needed for generation of action potential by most sensitive nerve fibers are presented
in Fig. 2.29 and show the initial state of the object and the state under hyperbary
impact. That means that analysis of the date from Fig. 2.29 can prove only that the
excitability of the fibers under hyperbary has decreased. Nevertheless, it should be
taken into consideration that the nerve fiber excitability decrease of the isolated nerve
occurs with the course of time and without an impact of hyperbary or other external
factors. Moreover, it can emerge spontaneously because of the preparation isolation
and impossibility to maintain metabolism. This peculiarity of the object under study
is shown in the fact that the value of the excitability parameters is constantly changing
being practically the time function of preparation aging of the nerve tissue outside a
living organism. Apparently, this can explain the constant decrease of action amplitude of the isolated nerve starting from a particular time moment (Fig. 2.30). At
the same time, hyperbary impact accelerates the amplitude contraction of the action
potential that means that the quantity of fibers capable to generate action potential
under the initial electrical stimulation has decreased. Such alteration of excitability
133
with the solitary nerve fiber were conducted according to the methods, described by
I. Tasaki [292, 374].
Methods of estimating the excitability. The excitability of the isolated solitary
nerve fiber was estimated according to the presence of action potential, the disappearance of which under continuous stimulation was considered as an irreversible
injury of the nerve fiber. The excitability of the nerve fiber as a part of isolated nerve
trunk was estimated according to the duration amplitude of the total action potential.
In a series of cases, such characteristics were recorded as excitability of the isolated
nerve, threshold value of electrical stimulation voltage with different duration of an
electric pulse (50, 100, 200 μs), to construct a graph duration-force. The excitability
of an isolated muscle fiber was estimated according to the presence of contraction in
response to electrostimulation and threshold (minimal) quantity of the voltage which
caused the contraction. An electromyograph produced by firm “Medicor” was used
for objects stimulation, amplification and observation of the action potentials.
To record the action potentials and isolated solitary nerve fibers stimulation, metal
electrodes were used which were placed inside the camera to investigate in such a
way that a simultaneous electrophysiological control is carried out during optical
measurements (see Fig. 2.14).
Results of the study. During electrophysiological control of vital functions of
the solitary nerve fibers, the attention was drawn to the irreversible suppression of
generation of action potential in the first seconds of high air pressure application. An
electrophysiological study of the isolated nerve was conducted to make sure whether
hyperbary is the reason of suppression of the ability of the nerve fiber to react with
action potential in response to electrical stimulation or whether it is a consequence of
mechanical injuries during preparing of solitary nerve fibers which often accompany
it.
Isolated sciatic nerves of a brown frog were object to the study. The total action
potential of the nerve fibers was analyzed in response to electrostimulation at the
frequency of 50 Hz during and after the high air pressure application (1 or 2 atm.).
The graphs illustrating statistically correct electrical stimulation voltage increase
needed for generation of action potential by most sensitive nerve fibers are presented
in Fig. 2.29 and show the initial state of the object and the state under hyperbary
impact. That means that analysis of the date from Fig. 2.29 can prove only that the
excitability of the fibers under hyperbary has decreased. Nevertheless, it should be
taken into consideration that the nerve fiber excitability decrease of the isolated nerve
occurs with the course of time and without an impact of hyperbary or other external
factors. Moreover, it can emerge spontaneously because of the preparation isolation
and impossibility to maintain metabolism. This peculiarity of the object under study
is shown in the fact that the value of the excitability parameters is constantly changing
being practically the time function of preparation aging of the nerve tissue outside a
living organism. Apparently, this can explain the constant decrease of action amplitude of the isolated nerve starting from a particular time moment (Fig. 2.30). At
the same time, hyperbary impact accelerates the amplitude contraction of the action
potential that means that the quantity of fibers capable to generate action potential
under the initial electrical stimulation has decreased. Such alteration of excitability