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Diurnal heart rate and body temperature in marmosets.

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Diurnal Heart R a t e and Body Temperature
in Marmosets
JOHN K. HAMPTON, JR.
T h e University of T e x a s Dental Science Institute at Houston a n d
T h e University of T e x a s Graduate School of Biomedical
Sciences at Houston, T e x a s 77004
ABSTRACT
Marmosets, Saguinus oedipus oedipus and S . fuscicollis, have
been shown to have a diurnal heart rate pattern that has a marked difference
between high and low values (about 5 5 beats/minute) and shows a low point
during daylight hours around 1300-1400 hours. A similar pattern for body temperature was seen. A species difference existed; the larger S. 0. oedipus has a
higher heart rate during both light and dark periods. All measurements were
made on undisturbed animals at hourly intervals using radiotelemetry. They
were kept in a controlled environment with a light cycle of 12L: 12D and a tem1°C.
perature of 27
*
Basic metabolic criteria, such as body
temperature and heart rate, are badly
needed if meaningful studies on marmosets are to be done. Diurnal variations, responses to ambient conditions, and species
differences may be critical to experimental
observations.
Morrison and Sim6es ('63) have studied
the diurnal body temperature of Callithrix
jacchus and its metabolic responses to variations in ambient temperature and activity. The pigmy marmoset, Cebuella pygmea, was more recently studied by Morrison and Middleton ('67). Similarly,
Scholander et al. ('50) examined the metabolic heat regulation of Leontocebus geoffroyi ( = Saguinus oedipus geoffroyi). A
limited zone of thermoneutrality and
marked diurnal variations were revealed
for these species. Not only does its metabolic heat production change considerably
as ambient temperature vanes, the marmoset has also been shown to be unable to
maintain body temperature very well whenever its environmental temperature varies
relatively little beyond or below its zone of
thermoneutrality.
New World primates such as Saimiri
sciurea, as well as the larger Lagothrix
lagotricha, seem to share with marmosets
this thermal lability when compared with
Old World primates such as Macaca
mulatta and M . speciosa (Chaffee et al.,
AM. J. PHYS.ANTHROP.,38: 339-342.
'69). Chaffee et al. ('66) have made it
clear that S. sciurea can undergo adaptation to hot or cold environments. However, they showed that changes in some
tissue enzymes do not occur as would have
been expected by extrapolation of data
from studies on rodents. Thus, the studies
reported here extend some of these data
to two additional marmoset species. By the
use of radiotelemetry it has been possible
to obtain body temperature and heart rate
around the clock in animals undisturbed
by capture or restraint and maintained in
a rigidly controlled environment.
METHODS
The marmosets used in this study were
adults; two males of S. fuscicollis and a
male and a female of Saguinus oedipus
oedipus. They were kept in a n isolation
chamber 4' x 4' x 4' made of three-quarter
in. plywood lined with acoustical tile.
Its door was fitted with a small one-way
glass port, and the animal was restricted
by a cage placed inside this unit. Good
ventilation was provided by forced, tempered air maintained at a temperature of
27" 2 1"C. Food and water was ad libitum.
A timed light cycle of 12L: 12D was used.
Telemetry units for heart rate were
manufactured by the E&M Instrument Co.,
Inc., Houston, Texas. The transmitters
were FM units, model 1100-E2 (18 gm) or
339
340
JOHN K. HAMPTON, JR.
1100-El ( 8 gm). They were carried on the
dorsum of the animals supported by a
harness made of insulated copper hook-up
wire. The transmitters were wrapped in
plastic for moisture protection and taped
to the harness. Batteries were changed
once each week. Silver ring electrodes were
implanted subcutaneously on the dorsum
of the animal in a straight line lateral to
the vertebral column and four to five centimeters apart. Teflon insulated leads
emerged from the skin in the neck region
and were undisturbed by the subjects. The
biotelemetry receiver (E&M Instrument
Co., Inc., Model FM-1100-7) was connected to a physiograph (E&M Instrument
Co., Inc., Model PMP-4A). This unit was
modified so that a timer activated a switch
to the paper-drive motor and to a solenoid,
which threw levers on the amplifiers from
the “idle” position to the “record” position.
The timer was set to provide a record for
three minutes at each hour. Heart rate was
measured by counting two apparently
typical 30 second intervals from each
three minute record.
We constructed our temperature transmitters after modification of the design reported by Stong (’68). The modification reduced the number of turns in each portion
of the coil by one-half. The thermistor used
was a 1 Megohm YSI 44015 (Yellow
Springs Instrument Co.) powered by a 1.4
volt mercury battery (Mallory 675), and
the transister used was an RCA SK3020.
This unit functions as a so-called “blocking” oscillator and transmits pulses with
a frequency that is varied by the effect of
temperature on the thermistor. The receiver was an ordinary, portable AM radio.
The pulsed out-put at the earphone jack
was carried to the signal input of a n ACDC preamplifier of the physiograph recorder and filtered there through a 0.2
microfarad capacitor.
The thermistor of the modified transmitter was placed at the tympanic membrane, and the transmitter encased in a
head bandage encircling the head. An impression of the auditory canals was made
with rubber-base dental impression material. A working cast was then prepared
and the final unit constructed of dental
acrylic. It consisted of a skullcap portion
carrying the transmitter and ear plugs,
one of which contained the thermistor; the
other ear plug was drilled to permit hearing. Body temperature at the tympanic
membrane was measured in one S. 0 . oedip u s . After a few days, the earplugs caused
irritation of the ear canals. This probably
could be avoided by using softer plastics
for the plugs or as a coating for the hard
acrylic.
RESULTS AND DISCUSSION
Measuring body temperature with a
sensor at the tympanic membrane seems
justified (Cooper, Cranston and Snell, ’64;
Benzinger and Taylor, ’63), especially since
ambient temperature was controlled (Nadel
and Horvath, ’70). Our findings for the
diurnal temperature pattern in this single
S. 0.oedipus was altogether similar to that
reported by Morrison and Simdes (’63) for
Callithrix jacchus. A change of about 4°C
was characteristic and showed the distinct
biphasic form during daytime with a low
point near noon.
Figure 1 presents the extensive data we
collected on heart rates from S. 0. oedipus
and S. fuscicollis. Diurnal variations were
clearly seen. Both species showed a n
abrupt rise from the nighttime low at 0600
hours to a daytime high at 0800 hours. A
depression corresponding to the afternoon
“siesta” occurred in both heart rate and
body temperature. The second heart-rate
peak was reached at 1700-1800 hours; the
rate fell within 4-5 hours to the first of
two nighttime lows. It was surprising to
find that the larger (by about 100 gm)
S. 0. oedipus had a faster heart rate than
the smaller S. fuscicollis. This difference
averaged 35 beats per minute at all hours.
The female S. 0 . oedipus did not differ notably from the male.
CONCLUSIONS
Marmosets, and perhaps New World
primates generally, have a narrow zone of
thermal neutrality. They are thermally
labile when ambient temperature exceeds
these limits despite marked changes in
oxygen consumption. We have shown that
diurnal heart-rate, as well as body temperature, varies characteristically and substantially. Thus, any temporal studies
using these animals must take into careful
account the time of day for sampling and
34 1
MARMOSET DIURNAL HEART RATE
S a g u i n u s oedipus
TWO ANIMALS
( C O T T O N TO PI
(*I657 & "1764)
STANDARD ERROR OF THE M E A N
A N D SIZE OF SAMPLE INDICATED
260.
w
2
[Y
IQ!
6
W
I
a
180
.
r
.
-
1
2
3
4
.
-
5
.
6
.
7
.
8
9
. . . . 14- . .17 .18 . . . -22 23. 2.4 .
10 I I
12 13
I5 16
19 2 0 21
HOUR OF DAY
( T A M A R I N1
Saguinus fuscico//is
TWO A N I M A L S
(*1514 &I - 1 5 1 6 )
S T A N D A R D ERROR OF T H E M E A N
A N D S I Z E OF S A M P L E I N D I C A T E D
22 0
210
200
ul
2
190
cz
180
Q
w
I
170
I60
30 45
I50
b
140
1
2 3
4
5 6 7
8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
HOUR
OF DAY
Fig. 1 Heart rates (beats/minute) taken at hourly intervals for two Saguinus oedipus
oedipus ( l a ) and two S. fuscicollis ( l b ) by radiotelemetry. Each datum represents the mean
( 2 S.E.) of the number of observations successfully made (noted below each bar) on both
animals for each species.
342
JOHN K. HAMPTON, JR.
observations. Furthermore, a constant and
optimal environment is necessary to avoid
great changes in baseline or experimental
values. Since a substantial species difference was observed, it, too, must be noted
in the design and report of studies. Finally,
these experiments make i t clear that the
comparative biology of primates warrants
a great deal more attention that it has
received.
ACKNOWLEDGMENTS
We wish to acknowledge the assistance
of Dr. Ronald Anderson and partial support from USPHS grant DE-02232.
LITERATURE CITED
Benzinger, T. H., and G. W. Taylor 1963
Cranial measurements of internal temperature
in man. In: Temperature - Its Measurement
and Control in Science and Industry. Vol. 3,
part 3. Reinhold, New York, pp. 111-120.
Chaffee, R. R. J., S. M. Horvath, R. E. Smith and
R. S. Welsh 1966 Cellular biochemistry and
organ mass of cold- and heat-acclimated monkeys. Fed. Proc., 25: 1177-1181.
Chaffee, R. R. J., W. C. Kaufman, C. H.
Kratochvil, M. W. Sorenson, C. H. Conaway and
C. C. Middleton 1969 Comparative chemical
thermoregulation in cold- and heat-acclimated
rodents, insectivores, protoprimates, and primates. Fed. Proc., 28: 1029-1034.
Cooper, K. E., W. I. Cranston and E. S. Snell
1964 Temperature in the external auditory
meatus as an index of central temperature
changes. J. Appl. Physiol., 19: 1032-1035.
Morrison, P., and J. SimBes, Jr. 1963 Body
temperatures in two Brazilian primates. Zool.,
261: 167-177.
Morrison, P., and E. H. Middleton 1967 Body
temperature and metabolism in the pigmy
marmoset. Folia primat., 6: 70-82.
Nadel, E. R., and S . M. Horvath 1970 Comparison of tympanic membrane and deep body
temperatures in man. Life Sciences, 9, Part I:
869-875.
Scholander, P. F.,R. Hock, V. Walters, F. Johnson
and L. Irving 1950 Heat regulation in some
arctic and tropical mammals and birds. Biol.
Bull., 99: 237-258.
Stong, C. L. 1968 The amateur scientist. Little
radio transmitters for short-range telemetry.
Sci. Amer., 218: 128-130; 132; 134.
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