Emotional stress developed in immobilized rats was shown to be accompanied by changes in the regulation of arterial pressure and the frequency of cardiac contractions. A group of adapting rats displayed definite resistance to emotional stress, while a group of rats incapable of adapting to acute emotional stress died with characteristics of cardiovascular insufficiency. The mechanisms providing resistance to emotional stress in numerous conflict situations were analyzed

Ivanona, L. I.

Skotselyas, Y. G.

Yumatov, Y. A.

English

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NASA TECHNICAL MEMORANDUM
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-76045
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DYNAMICS OF CHANGE IN RAT ARTERIAL PRESSURE
UNDER CONDITIONS OF IMMOBILIZATION
Ye. A. Yumatov, Yu. G. Skotselyas, and
L. I. Ivanova
Translation of "Dinamika izmeneniya arterial'nogo davleniya u krys v
usloviyakh immobilizatsii", Pathologicheskaya fiziologiya i
eksperimental l nava terapiya, No. 3, 1979, pp 22-26
(NASA-TN-76045) DYNAMICS OF CHANGE IN RAT
ARTERIAL PRESSURE UNDER CONDITIONS OF
	
N80- 17672IMMOBILIZE?TION (National Aeronautics andSpace Administration) 9 p HC A02
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NATIONAL AERONA TICS AND SPACE ADMINISTRATION
WASHINGTON, D. C. 20546
	 FEBRUARY 1980
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UDC 616.12-008.331-02%613.8631-092.9
DYNAMICS OF CHANGE IN RAT ARTERTAZ PRESSUREE UNDER
CONDITIONS OF IMMOBILIZATION
by
Ye. A. Yumatov,`Yu. G. Skotselyas, Z. I. Ivanova
Department of Normal Physiology of the I. M. Sechenov
First Moscow Medical Institute, P. K. A nokhin Scientific
Research Institute of Normal Fbysiology of the USSR
Academy of Medical Sciences, Moscow
It was shown that emotional stress accompanied by charac-
teristic peculiarities of the changes in the regulation of ar-
terial pressure and the frequency of cardiac contractions de-
veloped under immobilization conditions in rats. A group of
adapting rats with a definite resistance to emotional stress,
and a group of animals incapable of adapting to acute emotional
stress which died with phenomena of cardiovascular insufficiency
were revealed among thr experimental animals. The mechanisms
providing resistance to emotional stress in numerous conflict
situations are analyzed.
It has been shown that emotional stress develops under conditions of
	 22*
prolonged continuous negative emotional states accompanied by disorders in
behavior and self-regulation of the autonomic functions [ ,1,5,61.• One df
the leading autonomic indicators that characterize the development of
emotional stress is arterial pressure (AP). In emotional stress the
development of stable arterial hypertension is possible [2, 7-10, 14] which
is observed, however, not in every animal and man. In this respect in a
study of the mechanisms for the formation of tmotional stress it is important
to understand in what way in some cases indiv'dual negative emotional
reactions "are accumulated" and in the final analysis create lengthy stable
negative emotional excitation accompanied by the somato-autonomic disorders
*Numbers in margin indicate pagination in original foreign text.
1
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while in other cases thanks to the defense mechanisms a resistance to
emotional stress is formed.
In order to reveal the laws govexning the predisposition and resistance
of animals to emotional stress the given work studied the dynamics of AP
regulation and the frequency of cardiac contractions (FCC) in acute immobi-
lization stress in rats.
Technique
The experiments were conducted on adult male rats weighing 250 g. A
total. of , 6 experiments wero made.
The stress factor used was a single 30-hour immobilization Lll, 13, 161
in a close chamber and multiple regulated immobilization for 18 weeks: for
3 h in the first 4 weeks, for 4j h in the next j weeks, and for 8 h in
the 1g4st 9 weeks. During the experiment the AP was recorded from the tech-
nique we developed for chronic measurement of AP in rats under conditions
of free behavior L41. For this puxposo A thin catheter was implanted in the
rats through the caudal artery into the abdominal aorta. The AP was
measured with the help of R -37 pressure sensors (firm " Stetkhem", United
States), R-23 AA (firm "Galileo", Italy) and was dynamically recorded with
slow sweep (2 cm/h) on a N -340 self-recorder of domestic production and
with great sweep (10 mm/s) on a mingograph-81 (firm "Yelena", Sweden). The
recording was made of the systolic, diastolic and mean amount of AP. The
FCC was computed according to the AP recording. From the AP recording
with slow sweep an hour-by-hour computation was made of the average hourly
amount of AP and FCC.
Results and Discussion
As the control (8 rats) the AP was dynamically recorded in rats under
normal conditions of free behavior in cages. Here it was established that
the AP oscillations, in the animals did not exceed 10-12 mm Hg during the
entire time of recordinn and were mainly linked to the periodic exchange
of rest and activity. The initial level of the mean amounts of AP and FCC
in all the experimental animals comprised respectively 118.3
—
+1.3 mm Hg and
396+7 contractions per minute.
2
I
t
i^.
L^
S
Figure 1. Variants (A, B) in Dynamics of Average Hourly Value of AF and
FCC in Rats in 30-Hour Immobilization.
Here and in fig. 2 and 3: on x-axis--time of immobilization (in Yours); on
y-axis--left--mean amount of AP (in mi Hg); xight--FCC per minute.
The experimental observations of the AP and FCC regulation in immobili-
zation emotional stress made it possible to separate all the animals into
several groups. The initial AP and FCC levels in the animals belonging
to different groups did not differ statistically.
Rats were placed in,the first three groups who were able to adapt
to immobilization. In 6 animals in the first group the dynamics of change
in AP and FCC during immobilization did not differ significantly from that
of the animals in the control group and was characterized by relative
stability. However, in the majority of experiments in the indicated con -
ditions changes were recorded in the AP and FCC. Thus, in l', animals that
we had placed in the second group, in the first 5-6 h of immobilization an
increase in AF was observed by 20- 4.0 mm Hg with a subsequent gradual de-
cline and stabilization of it by the 23rd-26th hour on the level 20-30 mm Hg
lower than the initial (fig. 1, A). In this group of animals in the first
6-8 h of immobilization oscillations in the FCC were noted in limits of
350-450 per minute, in later periods (20-24th hour) the FCC was stabilized
on the level 400-450 per minute. Eight rats in the third group reacted
to immobilization by a slow, gradual reduction in the AF by 20-35 mm Hg to
stabilization by the 22nd-23rd hour on the level 80-100 mm Hg (fig. 1, B).
3
/25
The FCC in these cases was characterized by relative stability and remained,
in limits 350 -420 per minute for the entire time of immobilization. It
is characteristic that not all the experimental animals were able to adapt
to the stress situation. Fourteen rats died, apparently~ as a consequence
of the insufficiency of the adaptive mechanisms. Here the following dynamics
of AP and FCC were noted in them, that also made it possible to divide
these animals into several groups. In 7 rats placed in the fourth group,
in the first 10-16 h of immobilization a gradual increase in AP was observed
to 140-160 mm Hg with subsequent progressive drop (fig. 2, A). In the
animals in this group sharp rises were observed in the AP (by 20-30 mm Hg)
which could be maintained in-the space of an hour at a high level. During
immobilization in these animals FCC fluctuations were noted in the limits
300-500 per minute with the maximum during the AP rise. The animals of
this group died on the background of a sharp progressive drop in FCC. In the
several last hours of life the FCC in them dropped from 400 to 100 per
minute and lower -with a relatively high AP level (75-90 mm Hg). In these
rats during autoposy massive sections were noted of myocardial infarct.
	 24
For three experimental animals of the fifth group From the very beginning
of the experiment a progressive drop in the AP and FCC values was charac-
teristic. The death of these animals was observed at the 13th-17th hour
of immobilization (fig, 2 0 B), In this time the AP was gradually reduced
from 120 to 40-50 mm Hg by the last hour of the study and was 30 mm Hg 15
minutes before death. The FCC in t,is time was.reduced from 400 to 120
per minute.
For four rats in the sixth group a sharp increase in the AP by 45-60
mm hg and FCC to 600 per minute and above was characteristic in the last
period before death. These animals died in even earlier periods of immo-
bilization--in the 6th-10th hour of the experiment (fig. 3). It is
characteristic that the AP in animals of this group rapidly dropped from
145 to 25 mm Hg for the last several minutes before death. The FCC here
all the way to the last 1
-2 min. before death remained high--500
-550
 per
minute. During the greatest rise in AP and the greatest FCC value in the
animals of the given group rhythmic oscillations were noted in the mean
4
Figure 2. Dynamics of AP and FCC in Different Groups of Rats (A,B) in
Immobilization
(The average amounts of AP and FCC are presented on the graphs for 1 h and
for 15 min (column B). The mark at the and of the column--death of animal).
01 23455789 6	 7	 8.	 0123456789
eighth hour
Figure 3. Variant of Dynamics of AF and FCC in Rats in Immobilization
The averaged amounts of AP and FCC are presented on the graph for 1 h and 15
{{
	 min, 1 min. The start of the eighth hour is also presented in minutes.
l
	
ORIGINAL PAGE IS	 5
OF POOR QUALM
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amount of pressure in the limits .30 mm Hg.
The experiments made It possible to find	 certain forecasting cri-
teria from which one could foresee the death of the animal under conditions
of immobilization emotional stress.	 Thus, it was established that unfavorable
factors are periodic oscillations in the mean AP level in limits 15-20 mm Hg
with wave duration 15-30 min., sharp increase in AP in the space of an hour
by more than 40 mm Hg, progressIva decline in FCC for 5-7 h, and gradual
drop in AP by 30-40 mm Hg in 2-3 h.
Thus, among all the experimental animals rats were found that possessed a
certain resistance to acute immobilization emotional stress, and rats that
were predisposed to it who died under these conditions,on the background of
cardiovascular insufficiency.	 In this respect the question arises of
` whether the resistance in the rats predisposed to emotional stress can be
increased by repeated immobilization of them under the same experimental
conditions.
In a separate series of experiments on 8 rats after early (3-8 h)
cessation of the first immobilization in several days a second was conducted.
It was found that prolonged 18-week orderly (3-8 h daily at the same time)
immobilization resulted in complete adaptation and preservation of the
initial amount of AP and FCC in these experimental animals.
	 Thus, in the
rats predisposed to emotional stress who in all the forecasting signs in
the first immobilization could die revealed an increased resistance in the
second immobilization:
The experiments demonstrated that part of the animals could adapt under
conditions of acute emotional-negative situation linked to immobilization.
The other part, apparently, due to the insufficiency of the adaptation
mechanisms died as a result of sharp cardiovascular disorders and the
development of myocardial necrosis.
	 The adaptation of the animals to the
emotional stress can be increased by repeated short-term immobilizations.
The results of our experiments agree with the data of the literature
[11, 12].	 With repeated immobilizations
	
of rats a restoration was also
6
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observed [15] in the initial adrenalin level in the cerebral layer of the
adrenal gland which is reduced after single immobilization and remains
below the normal level more than a day. Only with prolonged negative
emotional states induced by irregular immobilization for several months
[11 0 12], constant zoosocial conflicts [13, 14], as well as the effect of
the stress situation [11, 12] do conditions occur for the development of
emotional stress with stable hypertension.
References
1. A pokhin, P. K. Vestn. AMN SSSR, No. 6 (1965), p. 10-18.
2. Val'dman, A. V.; and Kozlovskaya, M. M. Uspekhi fiziol. nauk, No. 1
( 1973), pp . 31-52.
y 3. Makarenko, Yu. A. Sistemnaya organizats_iya emotsional'nogo povedeniya
["Systems Organization o moaional Behavior" j, Author's abstract of
doctoral dissertation, Moscow, 1973•
4. Skotselyas, Yu. G.; Ivanova, 1. I.; and Yumatov, Ye. A. Fiziol. zh. SSSR,
No. 1 (1977), pp 87-93.
5. Sudakov, K. V. Pat. fiziol., No. 1 ( 1.975), pp . 3-12.
6. Sudakov, K. V. Vestn. ANN SSSR, No, 8 (1975), pp. 43-49.
7. Chazov, Ye. I. Ibid, No. 8, pp. 3-8.
8. Yastrebtsova, N. L.; and Simutenko, L. V. Byull. eks er. biol., No. 1
( 1976), pp. 20 -21.
9. Baumann, R.; Ziprian, H.; Godicke, W. at al., Psychother. Psychosom.,
	
26
Vol. 22 ( 1973), p• 131•	 n.
10. Folkow, B.; Hallback, M. and Weiss, L. C1in. Sci., Vol. 45 ( 1973), P-
1318-1335.
 Hecht, K.; Popal M. Paschal, M. at al., A cta biol. med. germ. Vol. '31,
t1973), PP . 913-A25.	 __wNU
12. Hecht, K.; Treptow, K.; Poppel, M. at al., Ibid, No. 27 (1971), pp. 8E9-883.....
13. Henry, J. P.; and Cassel, J. C. Am. J. Epidem. Vol. 90 (1969), p. 171.
14. Henry, J. P. at al., Circulat. Res, Vol. 36 (1975), P. 156-164.
15. Kvetnansky, R.; and Mikulaj, 1. Endocrinology, Vol. 87 (197u), P. 738-743•
16. Tsukiyama, H.; Otsuka, K. et al., Jap. Circulat. J., Vol. 37 (1973),pp. 1265-1269.
Copyright Holder:'patologicheskaya fizeologiya i eksperimental'naya terapTya"
1979
7
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Dynamics of change in rat arterial pressure under conditions of immobilization

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