File Name: SLS1_15.DOC

EXPERIMENT SLS1 BSP15

WEIGHTLESSNESS EFFECT ON WATER AND ELECTROLYTES IN THE ANIMAL BODY

[PIs:]{.underline}

[Russia:]{.underline}

L.V. Serova, Institute of Biomedical Problems, Moscow

Yu. V. Natochin, Institute of Evolutionary Physiology and Biochemistry,
Leningrad

[Co-Investigators:]{.underline}

E. I. Shakhmatova, Institute of Evolutionary Physiology and
Biochemistry, Leningrad

E. A. Lavrova, Institute of Evolutionary Physiology and Biochemistry,
Leningrad

E.V. Snetkova, Institute of Biomedical Problems, Moscow

S. Ya. Ivanova, Institute of Biomedical Problems, Moscow

[US]{.underline}

L. Keil, NASA Ames Research Center, Moffett Field, California

[Introduction]{.underline}

Beginning with the very first space research programs, a lot of
attention was given to the study of fluid-electrolyte metabolism,
probably, because water and electrolytes determine the course of
essentially all physiological processes in the human and animal body.

In the framework of the Cosmos project, we carried out a number of
experiments to study space flight effects on water, sodium, potassium,
calcium and magnesium in bone, muscles, skin, liver, kidneys and heart
of rats. Measurements were performed in the weightless state as such and
during provocative tests in space flight and after landing.

Postflight loading tests (for example, administration of KCl isotonic
solution) revealed differences between flown and control animals: flight
animals showed a lower total body potassium and its accelerated
excretion which can be explained by a reduction of the potassium pool,
particularly, of the muscle mass \[3, 4\].

Calcium loss that occurs in a prolonged space flight, negative calcium
balance and continuous hypercalciemia have been a serious problem as
related to long-duration space missions. Cosmos-1514 experiments
specifically addressed calcium metabolism in weightlessness. Obviously,
physiological systems are challenged by a simultaneous action of several
factors depleting calcium: this was taken into consideration in the
Cosmos-1514 experiment, in which pregnant rats were exposed to space
flight, and ground-based controls underwent all space flight effects
except for weightlessness.

The Cosmos-1514 experiments yielded important data about
fluid-electrolyte changes in flight. The body weight of female rats,
that were flown during pregnancy days 13 to 18, did not increase whereas
that of synchronous controls grew by approximately 60 g. Since in the
flown and control animals food consumption was identical and the total
weight of fetuses at birth was very similar, it can be postulated that
the mothers lost weight for the benefit of their offspring. For example,
the liver weight in the flight rats averaged 10.3 g versus 14.6 g in the
synchronous controls whereas the kidney weight remained virtually the
same \[5\]. The calcium content in the liver and kidneys of the flight
rats diminished significantly. It is very likely that the animal body
has a mechanism of distribution of electrolytes, particularly calcium,
the concentration of which in maternal organs diminishes, entering the
fetus. Parameters of fluid-electrolyte metabolism of the fetal body
exposed to weightlessness proved more stable than those of the maternal
body (16). These observations indicate that the animal body has a strong
capability not only to maintain the basic parameters of
fluid-electrolyte balance but also to redistribute water and
electrolytes between various organs and tissues.

After a 7-day Cosmos-1667 flight, the potassium concentration in the
heart and kidneys decreased and that in the skin and bone increased. The
concentration of sodium and magnesium in the kidneys also diminished
\[2\]. After 14-day (Cosmos-1887 and Cosmos-2044) flights such changes
were not detected; due to this, they can be associated with an acute
stage of adaptation to weightlessness.

In the SLS-1 project, we investigated the concentration of water and
electrolytes in rat tissues immediately and 9 days after a 9-day flight.
In previous experiments rats were not examined during the recovery
period.

[Materials and Methods]{.underline}

Measurements were performed, using samples of the heart, liver, kidney,
skin, muscle and bone (humerus) from basal control (BC) rats, flight
rats dissected immediately after recovery (R+0) and 9 days after
recovery (R+9), and control rats dissected on the same days (C+0) and
(C+9). The samples were weighed, put into quartz tubes, and dried at 105
oC to reach a constant weight in order to evaluate water content. The
dried samples were ashed by concentrated nitric acid. Sodium and
potassium were

measured in a Zeiss-111 flame photometer by means of a propane-air
mixture, calcium and magnesium were measured in a Hitachi (Model 508)
atomic absorption spectrophotometer by means of air-acetylene flame. The
results were treated using the Student\'s t-test.

[Results and Discussion]{.underline}

The results obtained are summarized in Tables 1 to 7. In terms of water
and electrolyte content, the control animals dissected at different
times (BC, C+0, C+9) showed significant differences (Table 1). This is
the reason why we compared the data obtained from the R+0 and R+9 rats
with the corresponding controls, i.e., C+0 and C+9.

In the bone samples (humerus), the content of water, sodium, potassium,
calcium and magnesium did not change at R+0 or R+9 (Table 2).

In the skin of R+0 rats, the content of water and sodium decreased
significantly while that of potassium, calcium and magnesium remained
unchanged. At R+9 no differences were seen between the flight and
control animals. It should be noted that

both groups exhibited a low (significant difference when compared to
other examination times) content of water, sodium, potassium and calcium
(Table 3).

In the skeletal muscle (femoral fragments) of R+0 rats, the content of
water, sodium, potassium, calcium and magnesium remained unaltered while
that of R+9 rats showed an increased content of water and sodium and a
decreased content of magnesium, when compared to the corresponding
controls (Table 4). It should be noted that the difference was due to
the decrease of the parameters in the controls; R+0 and R+9 rats

did not show any differences in relation to these parameters.

In the heart of R+0 rats, the content of water, sodium and potassium
decreased while that of calcium and magnesium remained unaltered (Table
5). At R+9 there was no difference between the flight and control rats.
It should be however mentioned that almost every parameter of the C+9
rats was lower than that of the C+0 rats (Table 5).

In the kidney, the content of water and electrolytes of R+0 rats was
identical to that of C+0 rats (Table 6) whereas the content of sodium
and calcium of R+9 rats diminished (Table 6).

In the liver, no differences were observed in the content of water,
sodium, potassium, calcium and magnesium in the flight and control
animals immediately or

9 days after flight (Table 7).

To facilitate the analysis of a large body of data obtained, they are
summarized in Tables 8 and 9. They indicate that fluid-electrolyte
homeostasis of animal tissues remained stable immediately and 9 days
after return to the Earth. The differences between the flight and
control animals were insignificant and the changes detected were,
probably, caused by water and electrolyte redistribution between various
tissues and organs. Of greatest importance is the decrease of potassium
in the heart which may be responsible for changes in cardiac function at
an acute stage of adaptation to weightlessness. It should be mentioned
here that a similar change, i.e., potassium decrease in the heart of
rats, was found after a 7-day Cosmos-1667 flight \[2\]. In all entirety,
the changes observed in SLS-1 rats were very close to those seen after a
7-day Cosmos-1667 flight and greater than those reported after 14-day
Cosmos flights. This gives support to our concept that fluid-electrolyte
changes typically develop at an acute stage of adaptation to
weightlessness. It is very likely that the greatest changes occur during
the very first days of exposure and that after 7-9 days in space only
\"tails\" of the changes can be discerned while after 14 days in space
they virtually disappear. However, the possibility cannot be excluded
that in longer-term space flights the above changes may reappear.

[References]{.underline}

1\. Denisova, L.A., Lavrova, E.A., Natochin, Yu.V. et al. Content of
Water and Electrolytes in Tissues. In: Ontogenesis of Mammals in
Weightlessness. Moscow, Nauka, 1988, pp. 45-47 (in Russian).

2\. Denisova, L.A., Lavrova, E.A., Natochin, Yu.V. et al. Content of
Water and Electrolytes in Tissues and Organs in Male Rats After
Cosmos-1667 Flight. Kosm. Biol. Aviakosm. Med. 1988, vol. 22, No. 2, pp.
33-37 (in Russian).

3\. Ilyin, E.A., Natochin, Yu.V., Ilyushko, N.A. et al. The Effect of
Weightlessness and Artificial Gravity on Ion Regulating Function of the
Rat Kidney. Kosm. Biol. Aviakosm. Med., 1980, vol. 14, No. 3, pp. 21-26
(in Russian).

4\. Natochin, Yu.V., Ilyushko, N.A., Kondratyev, Yu.I. et al. Ion
Regulating Function of the Kidney of Cosmos-936 Animals. Abstr. VI Natl.
Conf. Space Biol. Aerospace Med., Kaluga, 1979. Moscow, 1979, pp. 64-65
(in Russian).

5\. Serova, L.V., Chelnaya, N.A., Bryantseva, L.A. General Health
Condition of Animals. Body and Organ Weight. Blood Picture. In:
Ontogenesis of Mammals in Weightlessness. Moscow, Nauka, 1988, pp. 45-47
(in Russian).

6\. Serova, L.V., Denisova, L.A., Lavrova, E.A. et al. Parameters of
Reproductive Function of Animals. Characterization of Fetuses and
Placentas. In: Ontogenesis of Mammals in Weightlessness. Moscow, Nauka,
1988, pp. 71-74 (in Russian).

[Summary]{.underline}

After a SLS-1 9-day flight the content of water, sodium, potassium,
calcium and magnesium was measured in the liver, kidney, heart, skin,
skeletal muscle and bone of male rats. On the day of recovery the
content of water and sodium decreased in the skin and that of water,
sodium and potassium diminished in the heart. In other tissues no
changes were seen.

[Table 1]{.underline}

Water and Electrolytes in Animals of Various Control Groups

  -------- ------------ -------------------------------------------------
  Group    H20 kg/kg    mM/kg dry weight

  -------- ------------ -------------------------------------------------

  -------- ------------ ------------ ------------ ------------ ------------
           dry weight   Na           K            Ca           Mg

  -------- ------------ ------------ ------------ ------------ ------------

**B o n e**

  -------- ------------ ------------ ------------ ------------ ------------
  BC       0.85±0.01    284±7        80.3±2.2     2296±78      114±5

  -------- ------------ ------------ ------------ ------------ ------------

+-------+-----------+-----------+-----------+-----------+-----------+
| C+0   | 0.74±0.01 | 283±3     | 70.7±2.5  | 2625±105  | 115±4     |
|       |           |           |           |           |           |
|       | P1=0.001  |           | P1\<0.05  | P1\<0.05  |           |
+-------+-----------+-----------+-----------+-----------+-----------+

+-------+-----------+-----------+-----------+-----------+-----------+
| C+9   | 0.66±0.01 | 288±4     | 57.9±0.7  | 2654±69   | 114±3     |
|       |           |           |           |           |           |
|       | P1        |           | P1\<0.001 | P1\<0.01  |           |
|       | ,2\<0.001 |           |           |           |           |
|       |           |           | P2\<0.002 |           |           |
+-------+-----------+-----------+-----------+-----------+-----------+

**S k i n**

  -------- ------------ ------------ ------------ ------------ ------------
  BC       1.73±0.17    193±16       108±12       2.39±0.15    7.9±0.6

  -------- ------------ ------------ ------------ ------------ ------------

  -------- ------------ ------------ ------------ ------------ ------------
  C+0      1.51±0.1     171±13       100±5        2.59±0.21    6.8±0.4

  -------- ------------ ------------ ------------ ------------ ------------

+-------+-----------+-----------+-----------+-----------+-----------+
| C+9   | 1.27±0.06 | 136±7     | 87.8±4.6  | 1.23±0.06 | 6.5±0.5   |
|       |           |           |           |           |           |
|       | P1\<0.05  | P1\<0.02  |           | P1        |           |
|       |           |           |           | ,2\<0.001 |           |
|       |           | P2\<0.05  |           |           |           |
+-------+-----------+-----------+-----------+-----------+-----------+

**S k e l e t a l M u s c l e**

  -------- ------------ ------------ ------------ ------------ ------------
  BC       3.56±0.09    163±10       479±19       2.70±0.32    32.7±0.7

  -------- ------------ ------------ ------------ ------------ ------------

  -------- ------------ ------------ ------------ ------------ ------------
  C+0      3.39±0.07    149±16       483±10       2.59±0.24    31.8±0.6

  -------- ------------ ------------ ------------ ------------ ------------

+-------+-----------+-----------+-----------+-----------+-----------+
| C+9   | 3.17±0.03 | 127±6     | 473±2     | 2.53±0.17 | 30.1±0.4  |
|       |           |           |           |           |           |
|       | P1\<0.01  | P1\<0.02  |           |           | P1\<0.02  |
|       |           |           |           |           |           |
|       | P2\<0.02  |           |           |           | P2\<0.05  |
+-------+-----------+-----------+-----------+-----------+-----------+

**M y o c a r d i u m**

  -------- ------------ ------------ ------------ ------------ ------------
  BC       3.95±0.07    278±7        396±9        4.94±0.80    26.8±0.4

  -------- ------------ ------------ ------------ ------------ ------------

+-------+-----------+-----------+-----------+-----------+-----------+
| C+0   | 3.93±0.03 | 249±6     | 420±7     | 3.69±0.22 | 29.6±0.9  |
|       |           |           |           |           |           |
|       |           | P1\<0.01  |           |           | P1\<0.05  |
+-------+-----------+-----------+-----------+-----------+-----------+

+-------+-----------+-----------+-----------+-----------+-----------+
| C+9   | 3.32±0.04 | 204±6     | 386±24    | 2.43±0.11 | 27.6±0.7  |
|       |           |           |           |           |           |
|       | P1        | P         |           | P1\<0.02  |           |
|       | ,2\<0.001 | 1,2\<0.01 |           |           |           |
|       |           |           |           | P2\<0.001 |           |
+-------+-----------+-----------+-----------+-----------+-----------+

[Table 1]{.underline} (cont.)

Water and Electrolytes in Animals of Various Control Groups

  -------- ------------ -------------------------------------------------
  Group    H20 kg/kg    mM/kg dry weight

  -------- ------------ -------------------------------------------------

  -------- ------------ ------------ ------------ ------------ ------------
           dry weight   Na           K            Ca           Mg

  -------- ------------ ------------ ------------ ------------ ------------

**K i d n e y**

  -------- ------------ ------------ ------------ ------------ ------------
  BC       3.25±0.11    256±9        304±7        4.20±0.17    24.7±0.7

  -------- ------------ ------------ ------------ ------------ ------------

  -------- ------------ ------------ ------------ ------------ ------------
  C+0      3.43±0.09    258±9        326±23       4.77±0.29    25.8±0.7

  -------- ------------ ------------ ------------ ------------ ------------

+-------+-----------+-----------+-----------+-----------+-----------+
| C+9   | 2.84±0.05 | 228±6     | 289±9     | 4.34±0.22 | 22.5±0.7  |
|       |           |           |           |           |           |
|       | P1=0.01   | P         |           |           | P2\<0.02  |
|       |           | 1,2\<0.05 |           |           |           |
|       | P2\<0.001 |           |           |           |           |
+-------+-----------+-----------+-----------+-----------+-----------+

**L i v e r**

  -------- ------------ ------------ ------------ ------------ ------------
  BC       2.37±0.05    111±4        317±17       2.86±0.09    24.1±0.48

  -------- ------------ ------------ ------------ ------------ ------------

  -------- ------------ ------------ ------------ ------------ ------------
  C+0      2.54±0.11    115±11       328±18       2.76±0.50    24.0±1.1

  -------- ------------ ------------ ------------ ------------ ------------

+-------+-----------+-----------+-----------+-----------+-----------+
| C+9   | 2.01±0.15 | 103±6     | 281±3     | 2.52±0.59 | 31.1±8.6  |
|       |           |           |           |           |           |
|       | P         |           | P2\<0.05  |           |           |
|       | 1,2\<0.05 |           |           |           |           |
+-------+-----------+-----------+-----------+-----------+-----------+

[Table 2]{.underline}

**Bone**

  -------- ------------ -------------------------------------------------
  Group    H20 kg/kg    mM/kg dry weight

  -------- ------------ -------------------------------------------------

  -------- ------------ ------------ ------------ ------------ ------------
           dry weight   Na           K            Ca           Mg

  -------- ------------ ------------ ------------ ------------ ------------

  -------- ------------ ------------ ------------ ------------ ------------
  C+0      0.74±0.01    283±3        70.7±2.5     2625±105     115±4

  -------- ------------ ------------ ------------ ------------ ------------

  -------- ------------ ------------ ------------ ------------ ------------
  R+0      0.75±0.02    282±8        66.6±1.5     2493±24      119±5

  -------- ------------ ------------ ------------ ------------ ------------

  -------- ------------ ------------ ------------ ------------ ------------
  C+9      0.66±0.008   288±4        57.9±0.7     2654±69      114±3

  -------- ------------ ------------ ------------ ------------ ------------

  -------- ------------ ------------ ------------ ------------ ------------
  R+9      0.62±0.02    274±4        53.8±1.7     2552±28      116±2

  -------- ------------ ------------ ------------ ------------ ------------

[Table 3]{.underline}

**Skin**

  -------- ------------ -------------------------------------------------
  Group    H20 kg/kg    mM/kg dry weight

  -------- ------------ -------------------------------------------------

  -------- ------------ ------------ ------------ ------------ ------------
           dry weight   Na           K            Ca           Mg

  -------- ------------ ------------ ------------ ------------ ------------

  -------- ------------ ------------ ------------ ------------ ------------
  C+0      1.51±0.1     171±13       100±5        2.59±0.21    6.8±0.4

  -------- ------------ ------------ ------------ ------------ ------------

+-------+-----------+-----------+-----------+-----------+-----------+
| R+0   | 1.14±0.08 | 129±8     | 83.7±7.6  | 1.92±0.28 | 5.8±0.5   |
|       |           |           |           |           |           |
|       | P = 0.02  | P \< 0.05 |           |           |           |
+-------+-----------+-----------+-----------+-----------+-----------+

  -------- ------------ ------------ ------------ ------------ ------------
  C+9      1.27±0.06    136±7        87.8±4.6     1.23±0.06    6.5±0.5

  -------- ------------ ------------ ------------ ------------ ------------

  -------- ------------ ------------ ------------ ------------ ------------
  R+9      1.15±0.1     135±11       71.5±9.8     1.69±0.37    5.7±0.5

  -------- ------------ ------------ ------------ ------------ ------------

[Table 4]{.underline}

**Skeletal muscle**

  -------- ------------ -------------------------------------------------
  Group    H20 kg/kg    mM/kg dry weight

  -------- ------------ -------------------------------------------------

  -------- ------------ ------------ ------------ ------------ ------------
           dry weight   Na           K            Ca           Mg

  -------- ------------ ------------ ------------ ------------ ------------

  -------- ------------ ------------ ------------ ------------ ------------
  C+0      3.39±0.07    149±16       483±10       2.59±0.24    31.8±0.6

  -------- ------------ ------------ ------------ ------------ ------------

  -------- ------------ ------------ ------------ ------------ ------------
  R+0      3.32±0.05    158±9        492±8        2.59±0.15    32.8±0.6

  -------- ------------ ------------ ------------ ------------ ------------

  -------- ------------ ------------ ------------ ------------ ------------
  C+9      3.17±0.03    127±6        473±2        2.53±0.17    30.1±0.4

  -------- ------------ ------------ ------------ ------------ ------------

+-------+-----------+-----------+-----------+-----------+-----------+
| R+9   | 3.35±0.08 | 174±15    | 476±9     | 2.57±0.09 | 28.4±0.3  |
|       |           |           |           |           |           |
|       | P = 0.05  | P = 0.02  |           |           | P \< 0.02 |
+-------+-----------+-----------+-----------+-----------+-----------+

[Table 5]{.underline}

**Myocardium**

  -------- ------------ -------------------------------------------------
  Group    H20 kg/kg    mM/kg dry weight

  -------- ------------ -------------------------------------------------

  -------- ------------ ------------ ------------ ------------ ------------
           dry weight   Na           K            Ca           Mg

  -------- ------------ ------------ ------------ ------------ ------------

  -------- ------------ ------------ ------------ ------------ ------------
  C+0      3.93±0.03    249±6        420±7        3.69±0.22    29.6±0.9

  -------- ------------ ------------ ------------ ------------ ------------

+-------+-----------+-----------+-----------+-----------+-----------+
| R+0   | 3.65±0.03 | 217±7     | 379±6     | 2.62±0.66 | 28.9±1.2  |
|       |           |           |           |           |           |
|       | P \<      | P \< 0.01 | P \< 0.01 |           |           |
|       | 0.001     |           |           |           |           |
+-------+-----------+-----------+-----------+-----------+-----------+

  -------- ------------ ------------ ------------ ------------ ------------
  C+9      3.32±0.04    204±6        386±24       2.43±0.11    27.6±0.7

  -------- ------------ ------------ ------------ ------------ ------------

  -------- ------------ ------------ ------------ ------------ ------------
  R+9      3.32±0.07    215±11       377±10       3.82±0.85    27.8±0.4

  -------- ------------ ------------ ------------ ------------ ------------

[Table 6]{.underline}

**Kidney**

  -------- ------------ -------------------------------------------------
  Group    H20 kg/kg    mM/kg dry weight

  -------- ------------ -------------------------------------------------

  -------- ------------ ------------ ------------ ------------ ------------
           dry weight   Na           K            Ca           Mg

  -------- ------------ ------------ ------------ ------------ ------------

  -------- ------------ ------------ ------------ ------------ ------------
  C+0      3.43±0.09    258±9        326±23       4.77±0.29    25.8±0.7

  -------- ------------ ------------ ------------ ------------ ------------

  -------- ------------ ------------ ------------ ------------ ------------
  R+0      3.53±0.06    254±6        320±3        4.56±0.19    24.7±0.6

  -------- ------------ ------------ ------------ ------------ ------------

  -------- ------------ ------------ ------------ ------------ ------------
  C+9      2.84±0.05    228±6        289±9        4.34±0.22    22.5±0.7

  -------- ------------ ------------ ------------ ------------ ------------

+-------+-----------+-----------+-----------+-----------+-----------+
| R+9   | 2.88±0.02 | 212±2     | 299±5     | 3.75±0.06 | 23.7±0.9  |
|       |           |           |           |           |           |
|       |           | P \< 0.05 |           | P \< 0.05 |           |
+-------+-----------+-----------+-----------+-----------+-----------+

[Table 7]{.underline}

**Liver**

  -------- ------------ -------------------------------------------------
  Group    H20 kg/kg    mM/kg dry weight

  -------- ------------ -------------------------------------------------

  -------- ------------ ------------ ------------ ------------ ------------
           dry weight   Na           K            Ca           Mg

  -------- ------------ ------------ ------------ ------------ ------------

  -------- ------------ ------------ ------------ ------------ ------------
  C+0      2.54±0.11    115±11       328±18       2.76±0.50    24.0±1.1

  -------- ------------ ------------ ------------ ------------ ------------

  -------- ------------ ------------ ------------ ------------ ------------
  R+0      2.27±0.05    109±11       283±13       2.28±0.12    22.8±0.55

  -------- ------------ ------------ ------------ ------------ ------------

  -------- ------------ ------------ ------------ ------------ ------------
  C+9      2.01±0.15    103±6        281±3        2.52±0.59    31.1±8.6

  -------- ------------ ------------ ------------ ------------ ------------

  -------- ------------ ------------ ------------ ------------ ------------
  R+9      2.23±0.05    101±4        316±10       2.13±0.15    24.0±0.68

  -------- ------------ ------------ ------------ ------------ ------------

[Table 8]{.underline}

Changes in Water and Electrolytes in Rat Tissues After Space Flight

(Comparison Between R+0 and C+0)

  ------------------- ---------- ---------- ---------- ---------- ----------
  Tissue              H20        Na         K          Ca         Mg

  ------------------- ---------- ---------- ---------- ---------- ----------

  ------------------- ---------- ---------- ---------- ---------- ----------
  Bone                =          =          =          =          =

  ------------------- ---------- ---------- ---------- ---------- ----------

  ------------------- ---------- ---------- ---------- ---------- ----------
  Skin                ---        ---        =          =          =

  ------------------- ---------- ---------- ---------- ---------- ----------

  ------------------- ---------- ---------- ---------- ---------- ----------
  Skeletal muscle     =          =          =          =          =

  ------------------- ---------- ---------- ---------- ---------- ----------

  ------------------- ---------- ---------- ---------- ---------- ----------
  Heart               ---        ---        ---        =          =

  ------------------- ---------- ---------- ---------- ---------- ----------

  ------------------- ---------- ---------- ---------- ---------- ----------
  Kidney              =          =          =          =          =

  ------------------- ---------- ---------- ---------- ---------- ----------

  ------------------- ---------- ---------- ---------- ---------- ----------
  Liver               =          =          =          =          =

  ------------------- ---------- ---------- ---------- ---------- ----------

[Table 9]{.underline}

Changes in Water and Electrolytes in Rat Tissues During the Recovery
Period

(Comparison Between R+9 and C+9)

  ------------------- ---------- ---------- ---------- ---------- ----------
  Tissue              H20        Na         K          Ca         Mg

  ------------------- ---------- ---------- ---------- ---------- ----------

  ------------------- ---------- ---------- ---------- ---------- ----------
  Bone                =          =          =          =          =

  ------------------- ---------- ---------- ---------- ---------- ----------

  ------------------- ---------- ---------- ---------- ---------- ----------
  Skin                =          =          =          =          =

  ------------------- ---------- ---------- ---------- ---------- ----------

  ------------------- ---------- ---------- ---------- ---------- ----------
  Skeletal muscle     \+         \+         =          =          ---

  ------------------- ---------- ---------- ---------- ---------- ----------

  ------------------- ---------- ---------- ---------- ---------- ----------
  Heart               =          =          =          =          =

  ------------------- ---------- ---------- ---------- ---------- ----------

  ------------------- ---------- ---------- ---------- ---------- ----------
  Kidney              =          ---        =          ---        =

  ------------------- ---------- ---------- ---------- ---------- ----------

  ------------------- ---------- ---------- ---------- ---------- ----------
  Liver               =          =          =          =          =

  ------------------- ---------- ---------- ---------- ---------- ----------