IN V I T R O O X Y G E N C O N S U M P T I O N B Y
UROMASTIX
1529
Oxygen Consumption by Liver and Kidney Slices
of Uromastix Hardwickii
H . S . A L I A T H A R , S . N . H A S N A I N , a n d M . ZAIN-UL-ABEDIN *
Department of Biochemistry, Univeristy of Karachi, Karachi-32, Pakistan
(Z. Naturforsch. 27 b, 1529—1530 [1972] ; received July 7, 1972)
Carbohydrate oxidation, Oxygen consumption, Lizard
1. The carbohydrates were oxidized at a significantly faster rate by the kidney than by the
liver slices of uromastix.
2. The amount of oxygen consumed by the liver and kidney slices of uromastix is of the similar
magnitude.
The oxidation of foodstuff is the main source of
energy required by the animals for muscular activity, performance of external work, biosynthetic
processes and the maintenance of body temperature
by homeothermic animals. Higher forms of life like
vertebrates which have to carry out a larger number
of biochemical and synthetic processes as compared
to microorganisms and other lower animals require
more energy and thus utilise carbohydrates in a
number of ways. As the higher animals have to meet
the greater energy requirement, they oxidise carbohydrates completely. Extensive work has been done
on carbohydrate metabolism in mammals 1 _ 4 . Oxygen consumption studies in reptiles have been restricted to intact animals 5 ' 6 . The present work is
concerned mainly with the oxygen consumption and
carbohydrate oxidation by the liver and kidney slices
of Uromastix hardwickii.
Materials and Methods
1. Animals: The lizards, Uromastix hardwickii were
collected from fields in Karachi region and were kept
in wooden boxes until used. The animals of both sexes
were used and were kept without food for several days
before the experiments. The animals were collected and
used during the period May to October which is the
active period of these animals.
2. Tissue slicing: The animals were sacrificed by
cutting the blood vessels in the cervical region. The
animals were placed in the supine position on a wooden
operating board and were cut open. The left elongated
lobe of the liver and the two kidneys were used for
Requests for reprints should be sent to H. S. ALI ATHAR,
Department of Biochemistry, University of Karachi,
Karachi-32, Pakistan.
* Present Address: Prof. M. ZAIN-UL-ABEDIN, Max-Planck Institut für experimentelle Medizin, D-3400 Göttingen,
W.-Germany.
the preparation of slices. The slices were cut free hand
with a razor blade between two frosted glass slides.
The thickness of the slices was approximately 0.5 mm
and were kept chilled in normal saline till used.
3. Studies with tissues slices: a) Determination of
total carbohydrate content: At zero time before the
studies with the Warburg respirometer started a known
amount of slices was transferred to a tube containing
2 ml 30% warm KOH and digested in a boiling water
bath. The digest was made to a known valume and
total carbohydrate content determined by anthrone
method 7 .
b) Oxygen consumption: Tissue slices of known
weight ( 1 5 0 — 2 0 0 mg) were transferred to Warburg
flasks containing 2.5 ml 0.019 M reptilian phosphate
buffer pH 7.4, according to M A H E R 8 and 0 . 1 ml 2 0 %
(w/v) NaOH was added to the central well. The flasks
along with the manometers were transferred to water
bath at 37 °C and the oxygen consumption of the slices
was noted at various time intervals over a period of
three hours. Air was used as gas phase. At the end of
incubation period, the slices and the medium were analysed for total carbohydrates.
Results
The total carbohydrate content of the liver and
kidney slices of uromastix at zero time and at the end
of 3 hours of incubation period is shown in Table I.
The average total carbohydrate content of liver
slices at zero time was 3008 jug-% and at the end of
three hours incubation it was found to be 2902
/•ig-%. Thus a % drop in total carbohydrate content
in three hours was 3.5. The average total carbohydrate content of kidney slices at zero time and
after 3 hours incubation was 438 and 370 /ug-%,
respectively, thus a percentage drop in total carbohydrate content was about 15.2.
Table II and Fig. 1 show the time course of oxygen consumption by the uromastix liver and kidney
Unauthenticated
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1530
IN V I T R O O X Y G E N C O N S U M P T I O N B Y UROMASTIX 1530
Table I. Total carbohydrate content of liver and kidney slices
of uromastix at zero time and at the end of three hours incubation. The values are expressed in terms of f i g glucose/ 100
mg tissue.
Tissue
Liver
Kidney
Initial
Carbohydrate
Level
Final
Carbohydrate
Level
Difference
3008
± 73.8 *
438
± 4.60
2902
± 70.3
370
± 4.60
105.9
± 2.9
68.0
± 3.23
*130
"0,120
110
O)
S ioo
% Drop
§
90
i BO
| 70
3.53
± 0.1
15.20
± 0.9
3 60
O
30
S.E. Each value is a mean of six observations.
20
10
Table II. Time course of oxygen consumption by uromastix
liver and kidney slices by Warburg respirometer.
0
* Mean ±
Time
[min]
Liver
30
00
90
120
150
180
28.25
53.31
72.47
92.27
110.77
129.79
3.17*
6.44
8.98
11.0
12.87
15.67
24.82
45.95
65.93
85.71
105.46
125.66
±
1.72
4 : 3.99
±
5.11
±
6.75
±
9.09
± 14.19
* Mean + S. E. Each value is a mean of eight observations.
Each value represents /1\ oxygen consumed/100 mg tissue wet
wt.
slices by Warburg respirometer over a period of
three hours. The oxygen consumption by both liver
and kidney slices increased gradually, from 28.25
to 129.79 fA oxygen/100 mg tissue and 24.82 to
125.66/<1 oxygen/100 mg tissue respectively.
Discussion
The incubation studies with the liver and kidney
slices of uromastix have shown that the total carbohydrate content of the tissue decrease with time
(Table I ) . During the period of three hours incubation, there is a very little drop (3.5%) in the case of
liver while in kidney the drop is significant (15.2%).
During the same course of time, the oxygen consumption by these tissue slices has been steady
(Table I I ) . The oxygen consumption was 129.7 ,al/
100 mg liver tissue in three hours whereas it was
1
B . D . R o s s , R . HEMS. R . A . FREEDLAND, a n d H . A . KREBS,
G.
GAJA,
G.
RAGNOTTI,
F.
ZAZZERA, B i o c h e m . J. 1 0 9 , 8 6 7
3
H.
A.
KREBS,
D.
A.
GAJONE,
and
A.
BERNELLI-
DE
GASQUET,
P.
T.
GASCOYNE, a n d T . YOSHIDA, B i o c h e m . J. 8 6 , 2 2
[1963].
4
G . WEBER, P r o c . S o c . E x p . B i o l . M e d . 1 0 8 , 6 3 1
[1961].
5
W.
R . DAWSON and
G . A . BARTHOLOMEW, P h y s i o l .
I
1
!
I
90
120
150
180
Time in min.
—
6
J. R .
7
104 [1963].
F. W . FALES, J. biol. Chemistry 193, 113 [1951].
M. J. MAHER, Endocrinology 74, 994 [1964].
8
[1968].
BENNETT,
60
125.6 ju\/l00 mg in case of kidney slices. Although
the oxygen consumption in both the tissues is very
similar, the utilization of carbohydrate for the oxidative purpose is much less in the case of liver than
in the kidney. It is possible that other constituents
like lipids are also simulaneously being oxidised in
the liver. It is not surprising because the lipid content of the liver is high 9 . Moreover during hibernation the liver lipid content of this reptile is greatly
increased while the liver carbohydrate and blood
sugar levels are maintained. The elevated esterified
and non-esterified fatty acid levels in plasma of
uromastix also suggest a higher utilization of
lipids 9 . Higher specific activities of succinate dehydrogenase and glucose-6-phosphate dehydrogenase
in kidney than in liver have been reported recently 10 . Thus kidney can utilise carbohydrates to
a greater extent through oxidative mechanisms as
compared to liver. Our results of oxygen consumption studies and total carbohydrate content during
the period of three hours incubation further support
the greater ability of kidney to utilise carbohydrate
as compared to that of liver.
Biochem. J. 105, 869 [1967].
2
30
Fig. 1. Oxygen consumption by liver and kidney slices of
uromastix. ( o — o ) total 0 2 uptake by liwer slices, (x — x)
total O , uptake by kidney slices, ( o - - - o ) 0 2 uptake by liver
slices at each 30 min interval., (x - - x) 0 2 uptake by kidneyslices at each 30 min interval.
Kidney
±
±
±
±
±
±
—L _1
Zool.
9
TEMPLETON a n d
W.
R . DAWSON. P h y s i o l . Z o o l .
B . K . ZAIN a n d M . ZAIN-UL-ABEDIN, C o m p . B i o c h e m .
36.
Phv-
siol. 2 3 . 1 7 3 [1967].
10
S. N . HASNAIN a n d J. RAMWANI, Z. N a t u r f o r s c h . 2 7 b .
[1972],
29, 40 [1956].
Unauthenticated
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698