BLOOD DESTRUCTION DURING EXERCISE. · G. O. BROUN Per cent 300 100 700 500 1,300 300 t100 100 900 700 500 300 1300 100 1,1oo00 900 500 300 100 300 100 300 100 300 100 I i I I I I.-F3

BLOOD DESTRUCTION DURING EXERCISE.

III. EXERCISE AS A BONE MARROW STIMULUS.

BY G. O. BROUN, M.D.

(From the Laboratories of The Rockefeller Institute for Medical Research.)

(Received for publication, August 25, 1922.)

Observations already recorded' 2 offer strong evidence for theoccurrence of blood destruction during exercise. There are yetother phenomena which point to the same conclusion. It is wellknown that any considerable loss of blood from hemorrhage or de-struction of cells within the body is followed in the absence of com-plications by a definite increase in the number of reticulated redcorpuscles in the peripheral circulation. This reaction can be takentherefore as a direct indication that unusual demands for new cellsare being made upon the hematopoietic tissues. If exercise of cagedanimals produces such a well marked decrease in the red cell quantityas blood volume observations indicate,2 a demand for corpuscles toreplace this loss will inevitably result and this demand should bereflected in an increase in the number of reticulated cells.

Methods.

In order to rule out any possible influence upon the hematopoietic tissueof the methods employed to determine blood volume, a different series of animalswas used in the present work from those heretofore reported upon. 1' 2 Treadmillexercise was given them as already described. Dogs 17, 18, and 19 had beencaged for only a little over a month at the time observations were begun. Nos.20 and 21, by contrast, had been confined for over 4 months before the firstobservations and were caged and sedentary for a further 2 months prior to thesecond series. In enumerating the reticulated cells the method of Robertson3

was employed. 10,000 cells were counted in each instance. The number ofreticulocytes found in 10,000 red cells furnished the "count" of the animal. On

I Broun, G. O., J. Exp. Med., 1922, xxxvi, 481.2 Broun, G. O., J. Exp. Med., 1923, xxxvii, 113.3 Robertson, O. H., J. Exp. Med., 1917, xxvi, 221.

187

Dow

nloaded from http://rupress.org/jem

/article-pdf/37/2/187/1176474/187.pdf by guest on 14 June 2021

BLOOD DESTRUCTION DURING EXERCISE. III

the days on which exercise was given, at least two, and in some instances four,counts were made at intervals during the exercise period. The average of thesecounts has been employed for charting purposes. In the control periods beforeand after exercise only single counts were taken on any 1 day. Great individualdifferences were noted in the "normal" number of reticulocytes, but the variationsoccurring in the same animal from day to day, while considerable, were less marked.

The reticulated elements were followed on all of the dogs for a week or morebefore exercise. The average of the counts was taken as the "normal" for theanimal. In the tables, the counts are given as such, i.e. the number found in10,000 red cells, as well as in percentages of the previous "normal." In thegraphic representation in the charts, the variations are expressed in percentagesof this "normal."

In the single experiment each on Nos. 17, 18, and 19, and in the last of the twoexperiments on Nos. 20 and 21, hemoglobin, hematocrit, and red cell determina-tions were made as well as the reticulated cell counts. Owing to the wide varia-tions which result from changed cell distribution during a day of exercise, theblood was examined both before it and afterwards. The average of the twofindings is used in the tables and charts. The hemoglobin percentage was deter-mined by the method of Newcomer 4 in the case of Nos. 17, 18, and 19, and by thePalmer s method in the other two animals. Blood for the various counts wastaken from the marginal ear vein of Nos. 20 and 21, and in the other animals fromthe external jugular.

Reticulated Cell Changes.

The reticulated cell counts are given in Table I and graphicallyportrayed in Text-fig. 1. No. 17 shows a well marked response toexercise, first manifest on the 5th day of it, and maintained throughoutthe following week. Thereafter only occasional observations weremade; and when a practically normal count had been secured on the10th day after exercise, they were discontinued. The animal hadbeen confined but little over a month when exercise was begun. InNo. 18, confined an equal length of time, the reaction, while distinct,,assumes less considerable proportions. Only 5 days of exercisewere given. No. 19, also caged for but a single month, showed noreaction during the 1st week of exercise. This was continued, there-fore, into the 2nd week and a distinct increase in the reticulocytecount manifested itself. Dogs 20 and 21 had been caged over 4

4 Newcomer, H. S., J. Biol. Chem., 1919, xxxvii, 465.6 Palmer, W. W., J. Biol. Chem., 1918, xxxiii, 119.

188

Dow



G. O. BROUN

Percent

300

100

700

500

1,300 300

t100 100

900

700

500

300 1300

100 1,1oo00

900

500

300

100

300

100

300

100

300

100I i I I I I .-F 3

Da 14 12 10 8 6 4 2 0 2 4 6 8 10 12 14 16 18 20 22 24 6 30 32

TEXT-FIG. 1. Changes in reticulated red corpuscles during exercise.

189

700

500

l I . . . I . . . . . i l . . . .lll_ 1 1~ , /Ii || I I,:, , 'A

i v

Dow




M

0Xh

a0n~y asea 'euaou Jo luao Iad jo aoseazo Alea

sa!pas o luno a~aevae X Ge

0102 JoI T -Iou IO luav ad

- -E 0 luno [.de M I Elaelu

a·Cd - o ]o uuanoa I

~Zm E ° l'junoD-.ou o lua la

a.'t -IOU Jo un Qj a

'1unoD

-IoU Jo moala (I

*1u oc:t_x,. 10 JU03 J;),

.ia .rB

o 2 2 2·- ~~~~~~ ~ 40

0) 0) 0) 0g~~ ~~~ N NE N

0) 0) " 0) 00)C 0 2U - - P'~

ch - U) *o * X o o on

I V0 i) - 2o r0 k- 00

0 0b V m)' 0 m o CS~yh~~~~h ~e2 - C cS )

L U) N = c-~~~~~~~~~~~~L c

'0O'00000 00' 0 00 re

- - -o0 ')

_~ OS %o O U) 0) _

I~~~~~~~~I C) o1 _ Ci s s)4o 0

vn0\ tU 0- Wo

- - .- - ~~~~~~4 - -n o It 0 ' 00 U7 W

-- - - -~~~~~e *- C-

t- 00~~\

1) Il) oo) 2 oo)

00 0 - p)1

-S *2f' 41I 00 C o0

_ _ tS~C

I - - ) C) =)

_- 2- 41) 00 00

0- 2- If) _ _-

h~~~~~~~~~ _ , _l

_ _ _ 4

0)

N 0...........

; *O--=

vl C

0 _)

.0 0) 3 = X 0) 0)~~~~a

mo~lh~o~~r~cuN0)

190

0)

-1

,S

0-

.E

P4

4.'

0)

N

rz

.e

4-

vt-z-A

S .n . . I. .

_N _

Dow



G. O. BROUN 191

)0 4o

a

_q i i : ; : i ; i C: i o 4i m M M O _ - Iq; o c o S oo " 't I; q i ; V

CS VUX X U t + W mP; i i i ) ) ,) rn 0o 0 ...O0 ..e

O _ _ 50 CS t mb *-

0 o o 1- CS 1_ 00 CS _ .) 1 0 o 000 0 00 0.........

0_ c ) ' (9 _ C %0%e -o

0") 0% (9 '0 '0 (9 c' ~o t- t-

M9 (9 oo _a a _ (.M4M9 o --

M t_ 9D *n n M 00 oo o- o- W ) o X_N k- r- ___

d O b - 0 ( -a q _ (S -r.q .o 0 I

00 ') e d 0

-O V m N- h- -,C

(9 N ' 0) - 0 N -

O 0% .00 ) ( -4 .) 4% \ 0

- -9 ( - ( 4 9 - - -N

0) a') N N 0 O) - 9 0 °O 4

'0 V )O - '0 - - 0 .0 -

'0 +' '0 00 V)' 00 0 V) 0

( : :I 0) ::::)ed

. . . . . . . ...

. . .- - - -.9 .. .

. . .. . . ..... , , , _~· I. . ... . . . ........... ................................

.~~~~~~~~~~~~~~ . ...................C

Dow




months at the time of the first experiment upon them. The reticu-locyte curve of No. 20 shows a well marked reaction to exercise atthis time. On exercise again 2 months later, a definite reaction wassecured but one much less imposing than had previously occurred.Prior to exercise the blood of No. 21 showed but a very small numberof reticulocytes, 2 in 10,000 being the greatest number noted. Thoughthe actual counts after exercise were not high, they amount in per-centage terms to a very large increase. This increase was maintainedpractically throughout the 2 months elapsing before the secondexperiment. Nevertheless, during the second exercise period therewas a marked reticulocyte rise above the already heightened level.

Several interesting points deserve mention in connection with thecharacter of the reaction. First of all, the irregular wave-like char-acter of curves derived from successive reticulated cell counts underordinary circumstances should be noted. A single count is no reliableindex to this curve. In some instances (Text-fig. 1, Nos. 21A and20B) a slight increase in the reticulocyte count occurred during the1st day or two of exercise. This was followed by a distinct fall inthe count and only towards the end of the exercise period did a secondrise occur. In practically every instance the crest of the rise isreached after exercise has been discontinued, and the curve remainsrelatively high until hemoglobin and cell count have come backwithin normal limits. It may well be that the rise noted early inthe course of exercise represents the appearance of a certain reservesupply of cells held in the bone marrow for emergency purposes andthat these disappear from circulation during the following days,when the activity of the marrow has not yet increased. With thisincrease there occurs a second rise, near the end of the 1st week ofexercise.

Changes Shown by the Hemoglobinometer, Hematocrit, and Red Count.

In Tables II to IV and in Text-fig. 2 are given the data obtainedby the use of hemoglobinometer, hematocrit, and red counts on theseries of animals already dealt with. It will be noted that the find-ings are in complete general agreement with the results of blood volumedeterminations as previously reported upon, in that they indicatethe disappearance of a considerable quantity of blood during exercise.2

192

Dow



G. O. BROUN

Taken independently the figures would not offer conclusive proofof this destruction as they do not deal with total values for the body.Certain irregular fluctuations that will be noted may be due eitherto errors in the individual determinations or to local or generalchanges in the ratio of fluid to cells. For example, a persistentlyhigh plasma volume will suffice to account for the fact that thedepression of these curves persisted for nearly 3 weeks after exercisehad ceased. In Text-fig. 3 is given a composite picture of the changesin reticulocytes, hemoglobin, hematocrit, and red count. Whenevercounts were made on more than one dog on the same day the percent-age figures yielded by these counts were averaged and used for thecomposite chart. The general features of the curves leave room forno doubt of the changes.

It is a priori possible that the reticulated cell reaction may be dueto other causes than the stimulus of blood loss, as for example, tosome chemical substance engendered or liberated during exercise.If it be due on the other hand wholly to cell loss, then on promptreplacement of this loss from outside sources the rise in reticulocytesshould not occur. To test the point the following experiment wasperformed.

Preliminary blood volume determinations were made on two dogs previouslycaged during 2 months. Hemoglobin and reticulated cell counts were taken for2 days beforehand as well as daily during the course of exercise. The animalswere exercised on treadmills after the usual manner for 5 days. The reticulatedcell count showed at the end of this time an upward trend in both animals. Asecond blood volume determination was now carried out and the quantity of cellslost determined. Each animal was now transfused with blood from a compatibledonor to the amount that should on calculation exactly replace the loss of hemo-globin. No further exercise was given.

The results of this experiment are presented in Table V and Text-fig. 4. It will be seen that the usual increase in reticulocytes afterexercise did not occur. In fact the cell count fell below the previouslevel.

Yet another test:-If the increase in reticulated cells is due toanemia from blood destruction, an animal made plethoric artificiallyshould on exercise show no rise in reticulocytes so long as the bloodamount remains abnormally large.

193

Dow




lTunou o luoa ad Jo alaA AlNiea

sauaslo IOlad ruqoSomaq oaSaAB Xi(ai

~F;,~ . o I la

-, 0leao to luaJ aa

ou o uao .tab

Z; f R uqojouoaq ua3 laa

a.slaveIeuulou Jo I= 1a01

Z ~. E 'uqoloumaq lau3 .aj

-m~ uW iUoUrr p lJao laaZ °E W W uliqolmomaq lua

Z E *qol omaq waa aa

v re|woup lo lad

-c-ewa

tb _ _ _ _ _ - - w - - - _N C~~~~~

z 'I

c) Id-- - -0 - - - -

00 00 I- - e ~ ~ c. O00 0\ 0 0 0 \ O

0- oX -F t... 0' 'rt "0 '0 0

0000\0C t- rt

, o= o, o o C ON

0'.0\C 0 0\ %0 0\ 0\0 0

C\0C, 00 00000 0 O- r00-

r- :P 0 C t- 00 x\0 0

0-~ 000-4 0 0,M00

00 C4 , , ,c,.

o, oo o oo 0\ 0 EOoo oo

L0 0

00 00 00

00 -~~~~- t- 0-

-

13~~33 %W o oo h ts mes 8 '

- --0 OIO

3 o ' O

I ho o oot O lt 08to .

CS " 88 _ O_ _, _Q

I o ~O b 00 KI C O °O00 0 0

C> + a0 s 00-

. ... .

...

C .0~~~~~~~ . .

fi- _- _ - -H ~::::

_ _ __ -- - :::

..0 N a, ): : -

,I ~4 4- - -4 _ _ __-a c- · t*0m Nd

194

'.0

,Z

:4

4 ,0

r.1

e43J

~,Ei

Dow



G. 0. BROUN 195

o d4 O -

C,0) 0

C 0 e . . ..-

4 0~ 00 X-- t-

0o o 00 00 a 0 o )o a o o o oo o o o o~CI W ~Z1=::0'0

00 = co 00 r- s X- 0 4

41) - 0' 04 o ~4 O 0

o o o 00 00-- - -- - - n4

C, 30' C4 C~ oo C0 Cs C0 O C 00 m a 00 00 00-00 -00000

C,0 oo 0' 0 0'0 Cooo ' 0

m4 0 I n 0 0 m0 'm 004 0 -- 04- 4 04 q 0 cos o os o\o co~

C, C, C ,

- 00 -

%O C)0.%OC 00 0- - - 0

o '0 0 0' 0's '0 o so00 t- 00 00 0 00 0 10

oo 04 00 0 0 'o v)0 m 00o 00 0 4 - -4 -- - = - ~- - - - - -

+0 -~ C 3~h

:: 0 00 * 0 .::::

:~~~ :: :- :0 :4 : :: :

60)c

.)

0

0

d

a

S

4)4

0

a

.40

4

0

0

00

0

be

.0)

0)

Dow



s3uos aql ooslta3 po mat ad rnloA alxS AiBa

d p " g iVuoU Jo laQ lad

o lua*aad aumlo A

~' i ,.a [ e|luaou Jo lUar0 I0~tiig Gm eoslla,

l',eou Jo luao ad

; ~tfo luao a ad nloA

lo2n e bdanat

IVUUO 'ah,oAS

G~ ' h ~_

gp utO l lad

jo .m ald unIO A

V X E Y o pa s aa

3uo J Ina lad

d~~~~ir=-~~~912

lJuo od a na{a~ to:lr ;I mo

C'! o C,! v! cs4 L -cl O \O \O N 3o-~ Q\ h oo o

ov V va xwl t- s "'Or I IVpo~o~~a \~~a 2 ;8 ; lfn 9 ofi oo O

o, C, oo o o 0 o _0 o

0: cl 0 0 \0 ow O \a 0 00 in000 0 h

O O 0 i X

I~ ~ o U: B ;°° °°0_S OC 00 _1 0

Cs 0 0s0 00 u O 0 0

.e e O-'oO ~o ,b So0s _c 00 Chi _

>9 0 N 0\ 0 o U _

, ) e + $ q ,

196 BLOOD DESTRUCTION DURING EXERCISE. III

EC4

·saalt.^ aaAeeulmou p lna lad aaae IFia

I

tt

1F41d

a

J0

·- --

cl,

C * eaA, _ _A

V- e 0 0 _ 00 t- t- C2 o 0 c O2 C 00 00 00 00 0H

. .:- : ; ........

.fl ~ .9 4 ~::::::i:::: i

b -|. 44 ta 4 J~L_ UA,

Y$ )4 4 X~C,$ 4 4

Dow



G. O. BROUN 197

r r -:4) 4). c

0 0 go

w 1- * 8

00 0 0 0 2

*~ fi o'i0 u z__

%)0oooo4)U) o

oo oo 4 o 4 m C r

@ W SWS$

ll Ol lS Q V O O

o h o o oX

0t 0

oo V) o00 00 0 o

. . 2. ...

o~~~~~~~- r oo + Os n

. .) . .. 0

.~ '. . .....

. -. . .....

: : : ::::::

4). ..

. * . . .. 0 . ......

.SW

'n

0.

w4)

,0

S

4)

.4)

QI.

10

0

0

-

.)

0

0

.0

� 7,

Dow




samsngasefAv jvuou o uao lad jo aftiaaS Ajmo

saps Jo unoo pa aaAe Xiea

.. asseJaae leunou p luao so

i - unoD pad

a asOAv livwou 0 3UaD lad

*;uio0o pa-

d ~~~~~~~~~p''92wo~tv jrupumo JO ua3 lad

zp~Q 23 l)~unoa pAj

aB Z 9Auou Jo lUas 'ad

Z~~~l; *~lanoa paB

_= IB0aV Iuuou p lJo J lad

~0p.ad i~

°vIuoa pa

.e cd.E .

-Ic

x--~~~~~~~4 - 4- f 4-fi

e; 9 ¢ Q ¢d4.3------ 4-

4- ... .-

~,5·:5·~"4 '" "

00oo r -- - _ e Ch 0O Ch O O 0 C0 Cs

to eq o ~n

0 l4V ').40%0 -c ~ 4 08 000 0 0 0 00 0 00 0X 00 n ., 00 o

ox g oa o o o s

o co 8 m 8 ° 800xcocoo 00 0 0o oo oo c

I o 8 o oX oo

0 80 O 00 00 000 00 00 00

O OoO oo r t t

-4.0 i - 0

0 a0 0 0 00 0%

. O O-

00

0 0000 o o8 r

0 8% 00 8% °

o 0000oo

·. o . . . .

.e

4--

Q S .~~~.

E ~~ 1

4O 0) -04 s 04

-04J=~

40 - -O~)Ni C

401

198

q.

4

.E,

> b

t

ir4

.)4-

F4.

, 4

t4

14

.1

u

b

IQ

'A

E

ii

Dow



G. . BROUN 199

. O x t S O ," .a c3 a ,.S

N n o o o g -°8 8°-_ 1-. - u u B o U

00 003 00 00 00 00 0 0 0

o o oo o o o

0- 0- 0 0 0 - 00 0 0 0

oo 0- ( 8 O o o

g 0 00 - u7 (' 1") '"

0- 0- 0- 00 t- 00

oo0 00o 0- _ + 0- O co oN 0 0 _0

so rs o) o or 0 O

00 a o o

0 0- '0 I0 r 0 '0 0-0 000 0

00 00 O Nn I- _ 3o oo b 05 oo oo ov o

o0 ' ' o o 0- - ° h

. 0 0

Dow




HemnRlobhin

_

19_ a

F -i

vi~.C

17' 20

flume of cells _

- " F I/

4/; -...'I7 '

Day 1412 10 8 6 4 Z 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32

TEXT-FIG. 2. Changes during exercise shown by the hemoglobinometer,hematocrit, and red count.

In Dog 26, a normal animal caged for 3 months, the number of reticulocytes,per cent of hemoglobin, and number of red cells per cubic millimeter were followedfor 2 weeks. The animal was then given intravenously 550 cc. of citrated bloodfrom a compatible donor. This caused definite plethora. A period of 48 hourswas allowed for readjustment and then exercise was begun and kept up for 6 days.The blood volume was not followed.

As the chart shows (Table VI, Text-fig. 5), a slight fall in redcount and hemoglobin occurred during the exercise period, but bothremained above the normal level. The reticulated cells disappeared

17 e2

200

Percent

110

AM

90

80

70

100

90

80

110

100

90

80

hematoctit - er cent vo

I~ ~ I Ll9- r_ 1 Z 1T:.

'S

Corpuscles per c.mm.

xI n 2i0 ed

70

- - - i -- P -- - _ . _:--~-

_ .A., .-,... M.;r., Err iP i%.t ,. .%* . _ -j· . _ . . _ -

_ --i iU _ . \- eTIt _ _~ ,' C _ ; - ._ p GA : _ _ _ _. _-- _- _

I _ I _ __ _ t I-II:L

\

-- --

,1WIfii

ez o. :._ ._.. .,-4:

i i 0

- -- - -- -- -- - --- _ T _ A:

.r' -%Xij·A-A'Icd. + .le-- -

_I,/a2

%??Je N I/

G. . BROUN 201

a-

.4

U ', - ri

5 a

v)

.0

40

42 z )

0 0 [email protected] aN

!es -

e d t o o o0 00

;i'Z

;;t

1s

8P4:

,-:

: : . . .

.3

Dow



A/>-7 I i !

;- I -- ?-- - _,dii~

_, t_ __ i _ __ __._ _ _ _ _ , C

-F-~ ~ ;, , : ]XE41:Sbl~l~·· y-p

12 10 8 6 4 2 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 0J 32-- Reticulated red corpuscles-- emos bin

-..... HematdP it.--- Copuscles per, c.mm.

TEXT-FIG. 3. General comparison of the changes in the reticulated red cor-puscles with the hemoglobin, red count, and hematocrit.

PerC. .,

300

200 110

100 100

0 90

so

Day 2 0 2 4 6 8 10-Reticulated red corpuscles----....... Hemolobin---- Cell volume

TEXT-FIG. 4. Prevention of the reticulated cell reaction by transfusion.202

Per

600

500

400

300 110

200

100 100

0

90

80

Day

Dow



G. . BROUN 203

0

0

oo

o4)

a

1

0)0

040

N, N

u0) 0e 0) ,, ,

o 0· z - - . z x" vf ~ - - - -N _ '0o .4e0

CO 0\ O t. < C' C-ICC O0 .-O 00 r~

Cmr N c o xuz Org m swe qO

ON00 NC~,C0-- ON00 OON 4'. 'm n-o~ -~~ - ^

- N o fiN oo'ooo'o''

ON 00 -ON ~1'004'In 21c'1 C ONC - lq- - - D l C,

I _I O 1 rn _ 0 O J- t 0 t, -It 8 InO O O OC O _ C -I 00 O a,-f 0 r 00t . _ 43 43 -

00 00 t- - 0 0 00\o ooo . 'O C c. .

0 n C) O O 'E m 0o o 0 00 0 0 o 0 o

0 -

C-C m - CD- -om 4V I 0 .. t-00 o - s-t___s^

a__ x-----__

U1 C r

,o O rd + e m n + m wo o o _ X o .. . . . . .. . . . .

.vdI9P

_t__

.4

'4

ts

-

0).

e

.S

1:

X

>

N

I-

.4.

HN

;N0Z1

R-8 ;-

I: £04

.

,D

8 8u·

.I

. d4

40 v4

c#Eso , .

.5 t

o

C- 90. N0

04&T 1

4B4

14

z5z

Ian

i

4

0;

"aI1:

*N:

Dow




practically completely from the blood stream within 3 days afterthe transfusion and did not reappear during the exercise nor for morethan a week thereafter. By this time the red counts and hemoglobindeterminations had fallen below the normal level and in the courseof the next few days reticulated cells again appeared.

_ Percent180160

Q 140'@ 120

1008060

, 40200

Percent

130

120. I

110

tX90ioo80

,,

N

-j7.

Z

0

C.

-I

iI

Ir

-

0

U

C.)

i,

--x

i[ -.9

\

I-4V

......

.+.....

i -T-,,I Ii

IlI I1

Day 14 12 10 8 6 4 Z 0 4 tb 10 iZ1 lA 1 tb UJ

TEXT-FIG. 5. Absence of reticulocyte rise after exercise in a plethoric animal.

DISCUSSION.

The foregoing observations, in connection with those previouslyreported, yield a number of suggestions as to the reaction of the bonemarrow of caged animals to exercise. Obviously there is at first aperiod in which blood destruction is proceeding more rapidly thanblood formation. In most animals during this period the reticulatedcount is increased but little. The need for new cells is then as greator greater than during the following week when the animal is againresting. It is possible that reticulated cells are broken up morequickly during exercise than normal cells. However, in this casethe counts prior to each day of exercise should be higher than thoseat the end of it, and this was not regularly the case. One may believethat during the long period of confinement which preceded exercisethe bone marrow had become inert, perhaps even atrophied, as com-

-

1-

I

-

L

l!...

i 1

l

:

{_LI i

V_I %I..

-VU I -LUk

[%'J7'-I/ :_ _t . Ks7! . .- . Xt z I

1it

I _ I _ i \IA

S t I 4VJj7dT4I.-

204

l-�

- L ! -A-i

T Ad T : ,

-. Eex c-~# ,-r--l-,l- I-· ------- ·

l IA l .r' rFT11- 1i 1

-

-.r

1 t AL tX l l i

_

' -- -- ?] ½ 5,,

Dow



G. O. BROUN

pared with that of normal animals and it was for a time unable toproduce new cells to meet the sudden demand. More will be saidupon the point in a paper that is to follow.'

Unfortunately no reticulated cell observations were made in whichthe period of exercise was extended over several weeks. It is probablethat as the marrow adapts itself to the demands upon it, the numberof reticulocytes will fall to the normal.

The observations of this and the preceding papers taken togetherstrongly indicate that the rle of exercise as a pace maker in blooddestruction and formation is an important one. Just as a disusedmuscle becomes weakened, and atrophied, so presumably may abone marrow which is not constantly working to replace worn outcells lessen also in its functional ability. And with the sudden in-crease in blood destruction brought about by exercise there ensueswhat may be termed marrow decompensation.

As everyone knows, exercise is good for the body in many ways.One important effect would seem to be a stimulation of the hemato-poietic system to a high efficiency. This stimulus need not take theform of a reduction in the gross number of red cells through injuryto them, unless indeed the exercise is so overdone that blood destruc-tion exceeds the reparative abilities of the marrow. The loss of bloodthat has been demonstrated in sedentary animals2 produces a tempo-rary anemia in them only because their hematopoietic tissues are notin a condition to compensate for the increased corpuscular wear andtear. With mild exercise the increases in cell destruction and produc-tion should take place pari passu. And the result will be a marrow fitfor emergencies.

There are, of course, other stimuli to the hematopoietic tissues fromexercise besides the loss of blood cells. One thinks immediately of therelative oxygen lack consequent on increased metabolism. Air-hunger during violent exercise is often as great as that at high alti-tudes, and the resulting marrow stimulation should be as considerable.But this and kindred matters need not enter into present consideration.

The way in which the red cells are destroyed in increased quantityduring exercise remains undetermined. Rous and Robertson 7 have

6 Broun, G. O., J. Exp. Med., 1923, xxxvii, 207.7 Rous, P., and Robertson, O. H., J. Exp. Med., 1917, xxv, 651.

205

Dow




brought forward evidence for the view that normal blood destruction,and that of some pathological states as well, occur through a mechani-cal fragmentation of the erythrocytes. It was on the assumptionthat destruction of this nature would be increased by the wear andtear incident to the quickened blood flow of exercise that the presentwork was undertaken. The assumption has been borne out in thatan increased destruction has been found. But whether the lattercomes about by corpuscular fragmentation remains to be seen.

SUMMARY.

A definite increase in the percentage of reticulocytes occurs afterexercise in animals previously kept to a sedentary life. Concomitantchanges in the hemoglobin percentage, plasma-cell ratio, and redcount offer evidence in addition to that already reported by theauthor of the occurrence of an increase in blood destruction undersuch circumstances.

Replacement by transfusion of blood destroyed during exerciseprevents the reticulated cell reaction. Animals rendered plethoricand then exercised show no increase in reticulated cells while theplethora persists.

The fact is emphasized that exercise must be an important factorin the maintenance of an efficient hematopoietic tissue.

206

Dow



Documents

BLOOD DESTRUCTION DURING EXERCISE. · G. O. BROUN Per cent 300 100 700 500 1,300 300 t100 100 900 700 500 300 1300 100 1,1oo00 900 500 300 100 300 100 300 100 300 100 I i I I I I.-F3