Download Electrolyte Content of Rat Heart Atria and Ventricles

Electrolyte Content of Rat Heart Atria and Ventricles
By J. A. BARCLAY, M.A., M.B., E. J. HAMLEY, PH.D., AND
HELGA HOUGHTON, B.SC.
T
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HE PECULIAR property of the heart,
its spontaneous beating, makes it one of
the few tissues easily studied when isolated
and perfused artificially. The rhythmic beat,
provides a reliable and immediate check of
normal activity since any change in periodicity can be assumed to reflect changes in metabolism. Furthermore, any variation in the
pattern of the beat can be studied electrically
and provides a correlation with changes in
electrolyte content. The small size of the rat.
heart also provides a link with the tissue-slice
preparation which has usually been used for
electrolyte studies. In spite of these points the
electrolyte data available in the literature on
the rat heart do not present the different
chambers, i.e., atria and ventricles, as separate entities except for a few estimations
referring to the atria used as tissue-slice
preparations. The whole heart used as a perfused preparation has shown its distinct differences in the extracellular space and, therefore, the ionic intracellular concentration of
each chamber.
Methods
The rats were males, weighing 270 to 330 Gin.,
derived originally from Wistar strain albino rats,
killed by concussion. The hearts were removed with
utmost speed and mounted on a cannula for perfusion by Langendorff's method.1 Perfusate was
oxygenated (100 per cent O2) Ringer-Locke solution2 with 0.2 per cent glucose, having a pH 7 2
to 7.4 due to the sodium bicarbonate of the solution
(150 mEq./L. Na and 6.25 mEq./L. K). Analytic
grade reagents were used throughout with fresh
glass-distilled water. The perfusion pressure was
30 to 33 cm. solution, temperature 30 to 35 C. The
hearts were removed for analysis after 2 hours poinfusion.
Samples of tissue for assay were the whole
atrium or pieces cut from the ventricles, dried
quickly on "ash-free" filter paper, weighed and
deposited in 0.9 per cent saline. After 45 minutes
the saline was analyzed for inulin or sucrose (a
similar procedure was applied to control blanks).
Other samples were digested in 0.13SF HN0 3 solution for 24 hours and analyzed for sodium and
potassium by flame photometer. The same digest
was analyzed for chloride by Sanderson's method.3
Dry weights were obtained by dehydrating samples
of tissue on aluminum pans in an oven at 105 C.
until constant weights were reached after 12 hours.
Since it is impractical to assay inulin and sucrose
simultaneously, 2 series of preparations were run;
inulin, Cl and Na were analyzed on one and sucrose, Cl and Na on the other, the results for Cl
and Na being grouped. The number of estimations
was limited by the amount of material available
in each atrium or ventricle.
The rabbits were males weighing 2.5 Kg., from
common, mixed laboratory stock. The procedures
used were identical to those described above.
If the electrolyte content of a tissue is to
be studied in any detail, it is imperative that
extracellular space be measured accurately.
Several materials may be used. The most reliable is inulin, but sucrose, chloride and
sodium have been used frequently in the past.
Data on these 4 materials are presented in the
tables.
In view of the very high chloride and sodium values found in the perfused hearts,
values are also given from a sample of fresh,
uuperfused heart. Furthermore, the work has
been extended to include similar data from
perfused rabbit hearts so that a comparison
may be made with data in the literature and
to illustrate species differences.
Results
The data summarized in tables 1 through
4 include the mean values ± standard error
of the mean, followed by the number of samples (shown in parentheses).
Discussion
The extracellular tissue spaces of the right
and left atria and right and left ventricles
are all statistically different, irrespective of
Prom the Physiology Department, Birmingham
University, Birmingham, England.
Received for publication June 21, 1960.
1264
Circulation Research, Volume VIII, November 1960
ELECTROLYTE CONTENT OF HEART
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the method of estimation, and the data clearly
indicate that ventricular tissue spaces are
very much smaller than auricular tissue
spaces. There is no statistical significance between estimations of tissue spaces by inulin
and by sucrose except in the left ventricle.
The left ventricle in the adult rat has markedly smaller tissue space than the right. It
is a histologic fact that vascularization is
good, and in 2 hours perfusion time, equilibration of inulin with the tissue spaces should
have occurred easily. Trial runs showed no
increase in inuMn space after the first 20 minutes of perfusion, and Bleehen and Fisher4
have shown that in the rat heart the rate of
turnover of inulin has a diffusion half-life of
3 to 5 minutes, indicating that 2 hours perfusion time is more than adequate to allow
equilibrium to be reached. Further support
for the difference between right and left ventricles can be found from the other methods
of estimation; the chloride spaces in both perfused and unperfused preparations confirm
that the right ventricular space is larger than
the left. The rabbit data substantiate this difference between right and left, and if one
concedes that data from the whole minced
heart will give values that reflect the large
anatomic size of the left ventricle, the sucrose
space of the cat myocardium5 seems to be
even smaller than the rat's.
The data for intracellular ionic contents
of the perfused hearts clearly exhibit that
migration of ions across the cell membrane
during perfusion is great. This is not in itself
remarkable and may be due to the very high
chloride and sodium content of the perfusing
fluid when compared to blood. What is remarkable is that unperfused hearts examined
immediately after removal from the thorax
show high intracellular chloride and sodium
values, and these values are highest in the
auricles. This cannot be explained as a part
of a special mechanism of contraction in view
of the low values known for skeletal muscle
but may possibly be associated with specialized myocardial mechanisms of conduction
since even higher values have been reported
for A-V bundle.8
1265
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BARCLAY, H A M L E Y , H O U G H T O N
Intracellular Concentration of Perfused
Table 2
Rat Hearts*
Chamber
Sodium
Chloride
Right atrium
Left atrium
Right ventricle
Left ventricle
51.9 ± 0.7
58.0 ± 2.6
59.0 ±1.6
63.9 ± 1.5
Potassium
46.7 ± 0.8 (12)
(11)
(H)
(52)
(51)
54.2 ± 1.4
57.8 ± 1.7
60.8 ±1.6
64.0 ± 1.5
51.8 ± 1.2 (10)
58.2 ±1.6 (23)
62.4 ±1.8 (25)
(12)
(12)
(29)
(29)
84.9 ±1.6
83.4 ±1.8
81.1 ± 0.5
80.3 ±0.6
( 8)
( 7)
(28)
(29)
"Calculated from imilin space data: mEq./Kg. wet weight.
Intracellular
Table 3
Concentration of Fresh, Unperfused
Chamber
Chloride
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Right atrium
Left atrium
Right ventricle
Left ventricle
30.9 ±1.7
39.0 ± 2.5
22.7 ± 1.3
24.4 ±0.7
Rat
Hearts"
Sodium
22.3 ±1.8
24.5 ± 2.2
19.1 ±0.8
23.6 ± 1.7
(20)
(19)
(38)
(18)
Potassium
(20)
(20)
(18)
(19)
75.2 ±
79.9 ±
85.2 ±
89.0 ±
1.6
2.5
3.3
3.5
Water
(14)
(14)
(12)
(12)
80.2
79.0
77.2
75.9
±2.0
± 2.3
± 1.5
± 1.7
(8)
(8)
(9)
(9)
'Calculated from inulin space data: mEq./Kg. wet weight.
Table 4
Tissue Data for the Perfused
Chamber
Right
Left
Right
I ,eft
atrium
atrium
ventricle
ventricle
Babbit Heart*
Extracellular
Inulin space
25.6 ± 3.4
28.4 ± 1.5
21.4 ±3.2
11.8 ± 2.3
(6)
(6)
(6)
(6)
Intriicellulii r
Chloride
78.8 ± 5.2
76.5 ±4.6
91.3 ±3.6
80.6 ± 1.7
Sodium
(7)
(7)
(7)
(7)
51.8 ± 6.0
45.4 ± 5.6
67.2 ± 5.7
77.8 ±5.0
Potassium
(7)
(7)
(7)
(7)
50.0
57.0
46.3
54.3
± 1.5
± 2.4
±2.8
±2.5
W i iter
(7)
(7)
(7)
(7)
75.6 ±1.3
82.5 ± 1.0
S0.3 ± 1.0
83.1 ± 0.1
(7)
(7)
(7)
(7)
*Space: ml./100 Gin.; concentration: mEq./Kg. wet weight.
The increase of intracellular sodium during perfusion with Ringer-Locke solution
appears to coincide with migration of potassium that maintains the total intracellular
concentration of Na plus K unchanged over
a period of 2 hours. Similarly, increase in
intracellular water is significant in all chambers and is the prime effect of perfusion. It
may be that the reciprocal relationship of
sodium and potassium is part of a simple
mechanism by which electrolytes and water
invade the cell. This is not necessarily in the
form of isotonie solution uptake as suggested
by Leaf," since similar calculations applied
to our data for the heart do not confirm his
results which refer to brain and kidney tissue
slices.
It is hoped that these data will show the
.specificity of the tissue spaces and ionic contents of the different chambers of the heart
and thus aid in the elucidation of the mechanisms of myoeardial function.
Summary
Extracellular tissue spaces are compared
vising inulin, sucrose, chloride and sodium in
hearts perfused with Ringer -Locke solution
by Langendorff's method. Also chloride and
sodium spaces are given for uuperfused,
fresh hearts. From the inulin spaces the int raceHular chloride, sodium, potassium and
water concentrations in both perfused and
unperfused heart chambers have been calculated. Data showing the specificity of Hie
Circulation Research. Volume VIII. November 1900
ELECTROLYTE CONTENT OF H E A R T
a t r i u m and ventricles oi: the h e a r t are p r e sented.
Summario in Interlingua
Spatios tissiilar extracellular esseva coniparate, utilis.'into inulina, sucrosa, eliloruro, e natrium in cordes
pt'rfiiiiilitu con .solution do Ringer-Locke sccundo le
methodo de Langundorff. Etinm le spntios de eliloruro
o do natrium es date pro iion-perfundite cordes fresc.
Ab lo spatios de inulina, le concentratioiies intracellular do eliloruro, natriuni, kalium, e aqua osseva
calculate. Dittos deinonstrante le specificitate del
:itrio e del ventriculos dol corde es presentate.
References
1. HAJILEY, E. •)'.: Laugendorff perfusion of tlio
rat heart. J. Pli.ysiol. 149: (Proceedings), .1959.
2. LOCKE, F. S., AND ROSK.NMIKIM, 0.: Contributions
Downloaded from http://circres.ahajournals.org/ by guest on June 18, 2017
Circulation Research, Volume Vlll, November 19(10
.126"!
to physiology of the isolated heart. .1. Physiol.
36: 205, 1907.
3. SANDERSON, P. H.: Poteiitiometric determination
of chloride in biologic.il fluids. Biochem. J.
52: 502, 1952.
4. BLEEHEN, N. M., AND FISHER, Jt. B.: Action
of insulin in the isolated rat heart. J. Physiol.
123: 260, 1954.
5. BOBERTSON, W. B., AND PEYSER, P.: Estimates
of extracellular fluid volume of myocardium.
Am. J. Physiol. 184: 171, 1956.
6. DAVIES, F., DAVIES, E. E., FRANOIS, E. T. B.,
AND AVHITTAM, J}.: Sodium and potassium
content of cardiac and other tissues of the
ox. J. Physiol. 118: 276, 1952.
7. LEAF, A.: On the mechanism of fluid exchange of
tissues in vitro. Biochem. J. 62: 241, 1056.
Electrolyte Content of Rat Heart Atria and Ventricles
J. A. BARCLAY, E. J. HAMLEY and HELGA HOUGHTON
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Circ Res. 1960;8:1264-1267
doi: 10.1161/01.RES.8.6.1264
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