GLYCOGENESIS FROM GLUCOSE ADMINISTERED TO THE FASTING DOG

BY MARGARET DANN* AND WILLIAM H. CHAMBERS

(From the Department of Physiology, Cornell University Medical College, New York City)

(Received for publication, January 6, 1932)

INTRODUCTION

A complete, though temporary, loss of the ability to burn glucose was observed in dogs after a fast of 3 weeks or more with frequent exercise on the treadmill (1). During the first 4 hours after 50 gm. of glucose were ingested, the blood sugar rose to a high level and part of the sugar was excreted, but at least 30 gm. could not be accounted for either by excretion or oxidation. The fate of this fraction involves the question of whether or not the failure of oxidation is accompanied by an impairment in the process of storage of glycogen.

In a series of experiments by Junkersdorf and Mischnat (2), in which a fasting period of 11 days was employed, there was apparently no increase in glycogen in the liver and muscles after giving 3 gm. of glucose per kilo, for the livers contained, in four fasting dogs, an average of 0.90 per cent, and, in eleven dogs killed 2 to 10 hours after glucose ingestion, an average of 0.92 per cent; the corresponding figures for muscle were 0.21 and 0.20 per cent, respectively. No increase, on the average, was observed in the heart, while a small increase was found in the wall of the gastro- intestinal tract after 2 hours.

In contrast to these observations Cori (3) found that in rats fasted for 48 hours the ingestion of a diet rich in carbohydrates produced an increase in liver glycogen of nearly 4 gm. per 100 gm. of liver. Barbour, Chaikoff, Macleod, and Orr (4) obtained very similar results and also found that the muscle glycogen rose from 0.25 to 0.36 per cent.

* Fellow under a grant from the Josiah Macy, Jr., Foundation. 413

414 Glycogenesis from Ingested Glucose

As a step in the investigation of the problem of carbohydrate metabolism in “hunger diabetes,” determinations were made of the amount of glycogen deposited in the tissues, especially the liver and muscles, of dogs which had ingested glucose after a fast of at least 4 weeks. In order to obtain a more complete picture of the carbohydrate changes than could be derived from glycogen determinations alone, and as a check on glycolysis during the handling of the tissues, analyses were also made for other car- bohydrates and for lactates.

Methods

Three mongrel dogs, one female and two males, were used for the experiments. The procedure here described for Dog 51 (Table I) is essentially the same as that employed with the other animals. During 17 days of fasting the dog was exercised on the treadmill for nine half hour periods. On the 20th day, under amy- tal anesthesia, the semitendinosus muscle of the right leg was com- pletely exposed. The blood vessels were then clamped and the whole muscle quickly removed by a single cut across each end and through the blood vessels. The following day the function ofthe operated leg seemed unimpaired. Amytal was given again on the 22nd day of fast and the liver exposed by a mid-line incision. Two pieces of liver, about 7 gm. each, were excised by electric cautery, one from the lower border of the left lobe, the other from the vesicular lobe. The other semitendinosus muscle (left leg) was then completely removed. Blood was drawn from the heart on the 22nd day and again on the 27th day. The glucose was given on the 28th day. To make the conditions for absorption and utilization of the sugar comparable to those of the calorimeter experiments (l), approximately 4 hours were allowed to elapse before the anesthetic was injected. The procedure for the 28th day is tabulated in the following protocol.

9.36 a. m., ingested 25 gm. glucose 11.36 “ blood from heart 1.25 p. m., amytal anesthesia 1.43 “ blood from heart 1.52 “ excised tissue from margin of right lobe of liver 1.&j “ ‘I “ (I ‘I “ central “ “ “ 2.06 “ “ semimembranosus muscle of right leg

M. Dann and W. H. Chambers 415

2.10 p. m., excised right side of diaphragm 2.11 “ “ left ‘1 “ I‘ 2.12 “ “ apex of heart, rhythmically contracting 2.13 “ “ section from middle of left ventricle

The remainder of the liver was removed and weighed. The weight (sum of the parts excised after glucose ingestion) is given in Table II. The urine was collected from the bladder and the alimentary canal was then removed. Glucose was determined in the contents by Benedict’s method after precipitation of the proteins by heating to boiling with acetic acid.

The variations as to days of fast when tissue samples were taken are shown in Table II. Dogs 36 and 50 each received 50 gm. of glucose, part of which was vomited between 3 and 4 hours later.

Duplicate samples of tissue of 3 to 5 gm. each were rapidly prepared for carbohydrate analyses according to a method embody- ing suggestions by Evans (5). The muscle was divided longitu- dinally and each portion weighed on a torsion balance to within 0.1 gm. and immersed in 30 cc. of 75 per cent alcohol at -5” in a mortar surrounded by an ice-salt mixture. Liver samples were similarly treated after discarding the cauterized portion. Usually about 1 minute, and in no case more than 2+ minutes, elapsed between the excision of the tissue and its transfer to the alcohol. Each sample was minced with scissors, ground with a pestle, and rinsed with 10 cc. more of 75 per cent alcohol into a flask and kept at -5” to -8” for about 24 hours. It was then filtered through paper and washed with several 5 cc. portions of 75 per cent alcohol.

The filtrate was used for the determination of lactic acid and glucose, as described later, and the extracted tissue residue was analyzed for glycogen as follows :I The residue was pressed with a porcelain spatula to remove alcohol and transferred to a tube containing sufficient hot 60 per cent KOH to make 1 cc. per gm. of original tissue. The tubes were covered with funnels and kept in a boiling water bath for 3 hours. The samples were then partially cooled, diluted to 10 or 15 cc., and 5 cc. portions trans- ferred to centrifuge tubes, where they were nearly neutralized with concentrated HCl (litmus paper indicator). 1.5 cc. of 95 per cent

1 We are indebted to Dr. Esther M. Greisheimer for several suggestions (personal communication, 1929) which we have included in this modification of Pfliiger’s method.

416 Glycogenesis from Ingested Glucose

alcohol and sufficient water to make 10 cc. were added. After thorough mixing the samples were centrifuged, filtered, and a 5 cc. aliquot portion (equivalent to one-fourth or one-sixth of the original tissue) was mixed with 10 cc. of 95 per cent alcohol. The sample was left in the refrigerator overnight and the precipitated glycogen was separated by centrifugation and washed once with 95 per cent alcohol. Hydrolysis was carried out with 2.2 per cent HCl for 3 hours, after which the acid was neutralized to phenol red with 1 N NaOH. All glucose determinations were made by the Somogyi modification of the Shaffer-Hartmann method (6). A 3 per cent correction was added for loss during hydrolysis, as determined by Nerking (7).

The filtrates were treated with the Somogyi (8) protein-precipi- tating reagents (8 cc. of Reagent I, 1 cc. of Reagent II), made up to definite volume, shaken, and filtered. Lactic acid was deter- mined by the Friedemann-Kendall method (9) on a 10 to 25 cc. sample, after removing alcohol by diluting with 40 cc. of water and boiling down to 10 cc. The copper-lime precipitation was omitted as unnecessary for the purpose of these experiments since it had previously been found to make little difference in some diabetic blood and tissue filtrates.

Total reducing material in the Somogyi filtrate was determined and reported as “soluble carbohydrate.” The non-fermentable reducing substances included in this figure probably amounted to about 6 per cent, which was the average found in six filtrates which were subjected, after removal of alcohol, to yeast fermenta- tion according to the method of Benedict (10). The absence of higher hydrolyzable carbohydates was shown in two liver and two heart samples in which the average difference between unhydro- lyzed and hydrolyzed samples was found to be 2 per cent.

As a typical set of results showing the agreement between duplicate pieces of tissue, complete data on Dog 51 are given in Table I; glycogen and soluble carbohydrates are calculated as glucose, and the sum of these plus lactic acid (potential glucose) is given in the columns designated “Total.”

Since the experimental work described here was completed Evans, Tsai, and Young (11) have questioned the use of amytal in studies on liver glycogen. We selected amytal as preferable to the volatile or other anesthetics because the normal resting car-

TABL

E I

Carb

ohyd

rate

Cont

ent

of

Tiss

ues

durin

g Fa

st an

d 4

Hour

s af

ter

Gluc

ose

Dog

51,

weigh

t 6.

1 kil

os.

Day

of

fast

,. .

. .

. .

. . .

. .

. .

. .

Glu

oose

inge

sted

,gm

......

......

......

......

......

.

- 20

0 22

0 28

25

Tota

l G

ly-

Tota

l

9er

cent

0.44

4 0.

420

0.43

2

4.84

8 4.

705

4.77

7

1.64

4 1.

972

1.80

8

0.35

5 0.

305

0.32

9

- t1

i ) ) -

tt P

8 9 -_ 8

Lacti

c ac

id

Solub

le

G’y-

cYY

% co

gen’

drat

es*

-__

36~

cent

per

cm

Gly-

%

A2

:oge

n*

hy-

drat

es’

volub

le ca

rbe

Lacti

c

3kL*

ac

id

-- ‘W co

&t pet

te

n

0.05

4 0.

05:

0.07

3 0.

02t

-- ,gr

cent

pe

r te

n

0.02

1 0.

31s

0.01

5 0.

37:

____

0.

018

0.34

f

-- t??

cent

per

cm&

0.26

2 0.

042

0.17

7 0.

055

-- 0.22

0 0.

04i

~- 1.30

2 0.

24(

0.98

3 0.

251

~- 1.14

3 0.

24:

--

_

II , , -

r ) I i , -

wr

cell

0.02

: 0.

02!

De?

cenm

0.32

5 0.

258

Mus

cle,

Sam

ple

1. .

......

......

......

.. “

2 ...

......

......

......

. 0.

260

0.03

8 0.

321

0.03

(

0.29

1 0.

03<

0.02

t 0.

29:

0.32

Av

erag

e ...

......

......

......

......

...

Liver

, Sa

mple

1.

. ...

......

......

......

“

2.

......

......

......

....

0.06

4 0.

04

-- 0.30

4 0.

02:

0.24

3 0.

01;

-- 0.27

4 0.

02(

-- 0.06

4 0.

05:

0.05

7 0.

064

0.06

1 0.

05t

-~ 0.08

1 0.

03;

0.08

4 0.

08(

-- 0.08

2 0.

05t

0.01

: 0.

01:

0.01

:

1.55

: 1.

24i

1.40

1

4.52

4.

44

4.48

Av

erag

e ...

......

......

......

......

..

Hear

t, Sa

mple

1.

. ...

......

......

......

‘I

2.

......

......

......

....

1.52

1.

85

1.68

--

Aver

age.

......

......

......

......

....

Diap

hrag

m,

Sam

ple

1..

......

......

....

“ 2.

....

......

......

. 0.

23

0.14

Aver

age.

......

......

......

......

.. 0.

18

Bloo

d Befo

re

gluco

se...

......

......

......

.. 2

hrs.

afte

r gl

ucos

e.

. . .

. . .

. .

. . .

. . .

.

4 I‘

‘1

“ . .

. . .

. . .

. . .

. . .

. .

. .

0.00

: 0.

372

O.Ol

r 0.

163

0.02

1

l Ca

lculat

ed

as

gluc

ose.

Glycogenesis from Ingested Glucose

bohydrate metabolism of the whole body seems to be least affected by it. It has been shown that with the technique employed in these experiments (50 mg. per kilo of amytal injected intra- peritoneally) in the dog there is no rise in blood sugar, no significant change in the respiratory quotient from the 2nd to the 7th hour after its administration, no effect on the alkali reserve of the blood, and no evidence of adrenal stimulation in the form of chemical regulation of body temperature (Edwards and Page (12), Deuel, Chambers, and Milhorat (13,14)). The concentration of lactates in the blood is unchanged (unpublished data). While contrary to the results of Long (15) and those of Anderson and Macleod (16), the evidence of Hinsey and Davenport (17) and of Eggleton and Evans (18) distinctly favors the idea that this narcotic causes no serious decrease in muscle glycogen nor increase in muscle lactates. In their recent article on hexosephosphate in muscle (19) Cori and Cori again emphasize the advantages of anesthetizing rather than killing the animal to remove muscle for carbohydrate determina- tions. Evans, Tsai, and Young (11) found that in cats under amytal anesthesia for 4 hours the liver may lose about one-half of its glycogen, whereas the loss in the muscle is comparatively small. Large doses, 70 to 160 mg. per kilo, were injected sub- cutaneously or intramuscularly. Only a slight impairment in carbohydrate utilization was noted by Cori (20) in rats infused with glucose. In the unanesthetized controls 18 per cent of the sugar was deposited as liver glycogen, whereas in the amytalized animals this fraction amounted to 14 per cent. Hines, Leese, and Barer (21) report that amytal inhibits in dogs the glycogenesis from continuously injected glucose in the liver but not in muscle.

It is doubtful whether in our experiments the anesthetic seriously interfered with the comparative results on the increase in hepatic glycogen before and after glucose ingestion, as illustrated in Table I by the figures 1.143 and 4.484 per cent. Some indication of the extent of glycolysis in liver and muscle may be gained from the data on soluble carbohydrates and lactates. According to Simpson and Macleod (22) postmortem glycogenolysis yields lactic acid in the muscle, but glucose in the liver; and the normal level of the free sugar in the liver is only slightly below the normal range of blood sugar. On the 22nd day of fast (Table I) soluble carbohydrates in the liver averaged 0.245 per cent or about

M. Dann and W. H. Chambers

0.200 per cent more than the blood (0.032 per cent) or the muscle (0.047 per cent). It is difficult to explain this marked difference between hepatic and blood sugar concentrations as an amytal effect when one considers that the blood sugar level was not elevated, nor have we found the carbohydrate metabolism in- creased in the dog under these conditions. In the different experi-

TABLE II

Carbohydrate Content of Liver and Striated Muscle

Dog 36, male, weight 7 kilos; weight of liver 198 gm.

am. Per Pm Pm Per Per Per P@ Per cent cent cent cent per cent cent cent cent cent per cent

20 0.5490.0960.0570.702 0.5490.4840.0311.064 27 0.4420.0870.0690.608 -0.0940.8270.2690.0271.123+0.059 33 6 29 0.5540.0700.0740.698+0.0903.1320.4020.0313.565+2.442

Dog 50, male, weight 5.9 kilos; weight of liver 183.5 gm.

;;

30

1

4

1 ““250.0750.0340.434 0.2750.0670.0330.375 -0.059 /.375~234~.011~.620~

20 0.3310.1250.0340.489+0.1143.3260.4070.0183.751+3.131

Dog 51, female, weight 6.1 kilos; weight of liver 193 gm.

20 0.2910.0390.0180.348 22 0.2200.0470.0260.293 28 4 25 0.3280.0640.0400.432

* Calculated as glucose.

ments shown in Table II a period varying from 20 to 95 minutes elapsed between the administration of the anesthetic and the excision of the liver samples. There was no apparent correlation between the length of this interval and the amount of soluble sugar in the samples. The low concentration of lactates in the muscle, which was 0.018, 0.026, and 0.040 per cent on the 3 different days

420 Glycogenesis from Ingested Glucose

given in Table I, shows that only a small amount of glycolysis took place in this tissue.

Results

The data on the glycogen, soluble carbohydrate, and lactic acid content of liver and muscle tissues in all the experiments on the three dogs are summarized in Table II. Each figure represents the average obtained from two pieces of the same tissue.

The changes in carbohydrates in the three different dogs are in accord, although the relative values in each animal are different (Table II). In the striated muscle a gradual loss in glycogen with little change in other carbohydrates occurred during fasting. Samples taken 2 days apart from one dog showed a loss in total carbohydrate plus lactate of 0.055 gm. per 100 gm. of tissue. In the other two dogs, when the intervals were 5 and 7 days, the losses were 0.059 and 0.094 gm. per 100 gm. The amounts of glycogen remaining in the muscles after a long fast were 0.442, 0.275, and 0.220 per cent. Other carbohydrates and lactic acid brought the totals to 0.608, 0.375, and 0.293 per cent, respectively. After glucose ingestion the gain in muscle carbohydrates was definite in each case, being respectively 0.090, 0.114, and 0.139 gm. per 100 gm. of tissue. By far the largest part of this increase was in glycogen.

A much greater variation was observed in the liver glycogen during fasting than in that of the muscles. Values of 0.375, 0.549, 0.827, and 1.143 per cent were obtained, bearing no pro- portionate relationship to the length of fast. Almost as great a variability was found in the sum of the carbohydrates and lactates, which ranged from 0.620 to 1.401 per cent. In Dog 36, in which successive samples of liver were taken, no significant change in total was observed. During the 4 hours after the glucose was in- gested a marked increase in hepat,ic glycogen occurred, amounting to a total of 2.442, 3.131, and 3.376 gm. per 100 gm. of tissue.

Blood was drawn at the time that tissue samples were excised. The concentrations of glucose and lactate in the arterial blood are shown in Table III. During fasting the soluble carbohydrate content of the muscle was quite similar to that of the blood. After the glucose was given the characteristic large increase in blood sugar was seen in each case, whereas there was very little

M. Dann and W. H. Chambers 421

rise in muscle sugar. Relative figures for blood and muscle in each dog were 152 and 70, 377 and 125, 163 and 64 mg. per cent. Glycolysis probably explains the higher concentration of lactates in the muscle than in the blood, for the liver and blood were not essentially different in lactate concentration.

The cardiac muscles (Table IV) 4 to 5 hours after glucose contained 0.920, 1.497, and 1.808 per cent total carbohydrates.

TABLE III

Blood Sugar and Lactates

Dog No. Date

36 50

51

1931

Jan. 26 July 6

“ 9 “ 22 “ 27 “ 28

_

* Amytal anesth lesia.

Glucose, mg. per 100 co. Lactic mid. mg. per 100 cc.

“,;“;c”d’B”e”

--

33 71 27 75 30 75 22 32 27 38 28

2 --

359

372

4 6 2 -- --

192 192 152* 7 7

377* 377* 11 11 9 7

21 21 163* 14 163*

TABLE IV

Carbohydrate Content of Heart after Glucose Ingestion

Dog No. Day of fast Glycogen*

per cent 36 33 0.721 50 30 1.226 51 28 1.689

Soluble :arbohydrate* Lactic acid

per cent pw cent per cent

0.069 0.130 0.920 0.125 0.056 1.407 0.061 0.058 1.808

4

26*

21*

Total

* Calculated as glucose.

The glycogen content was considerably higher than that of the striated muscle of the same animal, while soluble carbohydrates were almost identical. Lactic acid was higher in the cardiac muscle, perhaps because autonomic contraction continued after excision.

It was anticipated that the regularly contracting respiratory

422 Glycogenesis from Ingested Glucose

muscle might resemble the heart in its carbohydrate content. However, the data of Table I show that the diaphragm is similar to the striated muscle of the leg rather than to the cardiac muscle in this respect. Additional results of the same type were obtained from Dog 50 and from another fasting dog without glucose.

DISCUSSION

The most striking and important point which these data demon- strate is that both muscular tissues and liver are able to form glycogen in an apparently normal manner, although the oxidation of sugars during this time is almost completely suppressed. In contrast to the results of Junkersdorf and Mischnat (2) the glycogen increase in the present experiments is closely cornpars ble to that found in rats by Macleod and his collaborators (4) and by Cori (3). The amounts of liver glycogen are similar to those reported by Fisher and Wishart (23), who obtained the

TABLE V

Comparison of Results with Those of Other Investigators I I

Authors No. Glycoeen

I I i& Nature of

experiment Muaole 1 Liver 1 Heart

per cent per cent per cent

Schenk (24) 12 Normal diet 0.46-0.57 0.37-0.51 Junkersdorf (25) 4 ‘I “ 0.55 6.1 Fisher and Lackey 3 Meat fed 0.58 1.81 0.50

(26) 2 Fast, 5 days 0.09 0.26 0.28 Junkersdorf (27) 15 ‘I 11 “ 0.21 0.59 Rathery and Kour- 3 “ 6-23 days 0.18-0.510.05-3.03

ilsky (28) 2 “ 30 days 0.18 0.20 5 “ 30-47 days 0.11-1.83

Junkersdorf and 4 “ 11 days 0.21 0.90 0.88 Mischnat (2) 3 “ 2643 days 0.10 0.40 0.56

This 3 paper “ 20-27 “ 0.224.550.38-1.14

percentages 3.33, 3.30, 3.85, 2.56, and 7.24 in well nourished dogs killed 1, 2, 2, 3, and 4 hours, respectively, after 50 of glucose. gm. The possibility of glycogenolysis in the liver due to the anesthesia has been discussed earlier in the paper. If such occurred at a rate proportional to the amount of glycogen present, or if some glycogen storage from ingested glucose was prevented by the amytal,

M. Dann and W. H. Chambers 423

there would have been a greater deposit of glycogen than is indicated by our experiments.

It is of interest to compare the amounts of glycogen found in the tissues of the fasted dogs with values reported by other investi- gators for normal and fasting animals. In addition to the experi- ments which we have already quoted, a few of the many analy- ses published for muscle, liver, and heart glycogen are shown in Table V.

The experiments of Schenk (24) are of added interest because he also determined lactic acid and other carbohydrates. He reported from 0.028 to 0.060 per cent lactic acid in muscle and from 0 to 0.067 per cent in heart, while “other carbohydrates” ranged from 0.10 to 0.13 per cent in both. These results are closely comparable to those given in Tables II and IV.

The average muscle glycogen found in our three dogs after 22 to 27 days of fast was 0.312 per cent, slightly higher than most investigators observed after fasts of varying lengths. The liver glycogen values fall within the range of variation found by Rathery and Kourilsky (28) in five dogs fasted between 30 and 47 days (chloralose anesthesia).

Some indication of the fate of the ingested carbohydrate can be obtained from the calculations of the amounts deposited and accounted for in other ways according to figures presented in Table VI. The analysis of the contents of the gastrointestinal tract gives evidence that practically complete absorption of 25 gm. of glucose takes place within 4 hours. The amount of sugar metabolized is estimated on the basis of previous experiments, including those published in 1930 (1) and three other unpublished calorimeter experiments in which the glucose oxidized during the 2nd, 3rd, and 4th hours after glucose ingestion following a 23 to 29 day fast averaged, respectively, 0, 0, and 0.03 gm. per hour.

In calculating the increase in blood sugar it has been assumed that the ratio of the blood volume to the body weight is 0.082 (Chambers and Coryllos (29)), without attempting to allow for a change in volume of blood or tissue fluids after glucose ingestion.

For the total muscle carbohydrate the value of 3 :7 given by Palmer (30) as the ratio of the weight of muscle to body weight of normal dogs is used. It is probable for emaciated animals this is more nearly correct than the ratio of 3 : 10 of Jur&rsdorf (25).

424 Glycogenesis from Ingested Glucose

While it is realized that the carbohydrate content of one leg muscle is not a valid representation of that of the whole striated muscula- ture of the body, on this basis the gain in carbohydrate in the muscle averages a little over 3 gm. If, also, the muscles had continued to lose carbohydrate at the same rate after the second sample was taken (Table II) as they had before, the increase after glucose ingestion would have been from 25 to 100 per cent higher than the amount shown in Table VI.

The increase in liver carbohydrates is based on the sugar con- centrations and weights of the organs given in Table II. Approxi- mately 60 per cent of the absorbed glucose is accounted for in Table VI and probably at least 35 per cent is deposited as glycogen in the liver and muscles at a time when practically none of it is being oxidized.

TABLE VI

Recovery of Ingested Glucose

Carbohydrates a8 glucose

Dog No. Ill- y$ RI?-

gested tained

---- gm. gm. gm.

36 45.6 16.7 28.9 50 50.0 29.6 20.4 51 25.0 0 25.0

* Not determined.

Present Metaba 1 gasCo- lised l;~t$lal $p;>

-- c7m. gm.

* 0.8 1.2 0.5 0.2 0.5

In addition to the possibility tha t more glycogen was stored

- ,-

, 1 --

I

Increase in tissues Exmkd __.

el Liver In urine 3lood Muscle -- gm. gm.

0.46 2.7 1.46 2.9 0.62 3.6

-- gm. gm. 4.8 3.8 5.8 3.1 6.5 3.9

Total ac-

:ounted for

gm.

12.6 14.9 15.3

in the muscles and liver than is calculated, a further fraction of the ingested glucose can undoubtedly be accounted for by storage in other organs and especially in the skin and subcutaneous tissue. Folin, Trimble, and Newman (31) found that following the injec- tion of sugar into dogs the skin contained as much glucose as the blood and more than the muscles. Determinations of glycogen in subcutaneous adipose tissue were made by Hoffmann and Wertheimer (32) and by Scoz (33), who found 2 per cent and even higher in dogs fasted for 2 or more days and then given a diet rich in carbohydrate.

Consideration must be given to the heart as a possible storage

M. Dann and W. H. Chambers 425

place for fairly large amounts of glycogen. Some results in the literature on heart glycogen of dogs in various states of nutrition were brought together in 1927 by Junkersdorf and Hanisch (34). Individual variations were considerable, but the average values reported by several authors for normal animals ranged from 0.39 to 0.46 per cent, while six dogs which had fasted from 3 to 56 days averaged 0.43 per cent. A more recent art.icle by Visscher and Mulder (35) gives 0.56 per cent as the average for twenty-six normal hearts.

The very high heart glycogen (0.72 to 1.69 per cent) found in our experiments after fasting and one dose of glucose is of the order observed by Fisher and Lackey (26) for depancreatized dogs and by Junkersdorf (36) for phlorhizinized animals. The amounts of total carbohydrate and lactate in the heart (Table IV) are very close to those found in three depancreatized dogs whose tissues were analyzed by the same technique (unpublished data). The hearts from these diabetic dogs contained 1.2 to 1.8 per cent carbohydrate.

SUMMARY

Determinations of glycogen, glucose, and lactic acid were made on portions of the liver and muscles of three dogs fasted 3 weeks or more, and on the same tissues 4 to 6 hours after ingestion of glucose.

No serious derangement in the process of glycogen formation was produced by a fast sufficiently long to suppress almost all oxidation of carbohydrate. An increase in total carbohydrate and lactate of 0.1 gm. per 100 gm. of muscle, and of 3 gm. per 100 gm. of liver, occurred after sugar ingestion.

Absorption of 25 gm. of glucose from the alimentary tract was practically complete within 4 hours. The blood sugar reached a maximum in about 2 hours and fell gradually.

Heart glycogen was found to be unusually high, comparable to the values characteristic for pancreatic diabetes, whereas the carbohydrate content of the diaphragm was about the same as that of the striated muscle in the leg.

Of the glucose absorbed about 60 per cent was accounted for and at least 35 per cent was deposited as glycogen in the liver and muscles.

Glycogenesis from Ingested Glucose

BIBLIOGRAPHY

1. Dann, M., and Chambers, W. H., J. Biol. Chem., 89, 675 (1930). 2. Junkersdorf, P., and Mischnat, H., Arch. ges. Physiol., 224, 151 (1930). 3. Cori, C. F., J. Biol. Chem., 70, 577 (1926). 4. Barbour, A. D., Chaikoff, I. L., Macleod, J. J. R., and Orr, M. D.,

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