SOLO SOdium LOad in microgravity

Standardized Study Conditions on the ISS and on Earth

Dr. Petra Frings-Meuthen DLR, Institute of Aerospace Medicine

Study managementStudy protocol

Volunteer selectionVolunteer rules

ISS experimentsBed rest studiesaccording to

ESA standardization plan

(Para) Medical CareNutrition

Biological samplesData management

n = 6-8, COLUMBUSSOLO

Common High salt intake+ controlled diet

Low salt intake+ controlled diet

day 1 day 5 day 1 day 5

• 24-h urine collection• blood draw

• blood gas analysis• body weight measurement

Petra Frings-Meuthen1, Martina Heer2 & Scott Smith3

1DLR, Institut für Luft- und Raumfahrtmedizin, Köln2Universität Bonn, Profil Institute for Clinical Research, Neuss

3NASA Johnson Space Center, Houston, USA

ESA: ELIPS ILSRA-2001-028

• 2 x 5 days inflight•2 x 5 days postflight (R+6-12 months) baseline data collection (BDC)

Sodium retention

microgravityvery high salt

ECV

sodiumexcretion

Sodium retention

without fluid retention

Drummer et al. EJCI 2000; Heer et al AJP 2000

ECV= Extracellular volume

Hypothesis 1

Higher salt intake in microgravity leads to sodiumretention without fluid retention• Sodium balance (intake, excretion)• Water balance, body weight

„High salt intake exacerbates immobilisation induced bone loss accompanied by changes in the acid-base and electrolyte system“

(DLR Salty Life 7 study, 2005)

study days

0 2 4 6 8 10 12 14 16 18 20

urin

ary

CTX

-exc

retio

n (µ

g/d)

0

2000

3000

4000

5000

6000

7000

8000

90000.7 mEq NaCl/kgBW/d7.7 mEq NaCl/kgBW/d6°HDTBR

high vs low salt

p < 0.001ANOVA „treat“

47%

Bed rest period

Frings-Meuthen et al. J Appl Physiol (in press)

Hypothesis 2

Standardisation:Nutrient intake

Environmental conditionsPhysical activity

Sampling & Analysing methods

Higher salt intake exacerbates microgravity induced increased calcium excretion & bone resorption• calcium excretion• bone resorption marker• bone formation marker

Energy (kcal) Protein (g) Fat (g) CH (g) Na (mg) K (mg) H2O (g)BreakfastApple Cider 113 0,1 0 28 29 4 250Cocoa 198 3,1 1 44 144 507 175Sausage Pattie 118 9,8 8 1 589 179 50Split Top Roll 160 4 5 24 300 0 18Grits with Butter 116 2,3 0 26 624 54 125LunchLemonade 82 0 0 20 25 2 250Hot & Sour Soup 65 3,5 1 10 297 132 155Beef Fajitas 159 28,9 4 1 763 453 90Tomatoes & Artichokes 74 2,5 4 8 489 526 191Pears 96 0,3 0 24 21 97 104DinnerPeach Apricot Drink 133 0 0 33 32 2 250Chicken w/ Peanut Sauce 234 22,5 5 25 446 538 64Potatoes au Gratin 147 4,2 8 14 581 157 100Creamed Spinach 65 3,3 2 9 560 245 50Cherry Blueberry Cobbler 308 2,1 9 54 148 184 104SnackApple Cider 113 0,1 0 28 29 4 250Blueberry Raspberry Yoghurt 140 4,5 1 28 50 163 113Almonds 272 11 23 2 305 282 6SUM 2593 102,2 71 379 5432 3529 2345

Energy (kcal) Protein (g) Fat (g) CH (g) Na (mg) K (mg) H2O (g)BreakfastChocolate Breakfast Drink 14 10 1 24 149 532 175Granola w/Blueberries 246 7,4 10 32 53 361 50Berry Medley 97 1,1 0 23 1 165 60Waffles 200 2,9 12 21 149 73 7Orange Drink 112 0 0 28 29 4 250LunchApple Cider 113 0,1 0 28 29 4 250Sweet & Sour Chicken 144 21,5 2 11 192 236 100Potato Medley 101 1,9 2 18 28 212 120Blueberry Raspberry Yoghurt 140 4,5 1 28 50 163 113DinnerPeach Apricot Drink 133 0 0 33 32 2 250Chicken Pineapple Salad 131 10,8 6 7 329 200 75Barbecued Beef Brisket 192 25,4 5 12 368 395 61Green Bean & Potatoes 48 1,6 1 9 206 296 102Cherry Blueberry Cobbler 308 2,1 9 54 148 184 104SnackLemonade 82 0 0 20 25 2 250Macadamia Nuts 312 4,7 27 12 0 117 0Cocoa 198 3,1 1 44 144 507 175SUM 2571 97,1 77 404 1932 3453 2142

High Salt

Low Salt

SOLO Hardware: standardized proceduresMeasuring urine

volume via scaling

Blood gas analysisBody mass measurement

Blood draw

Urine collection

Experiment Status

ISS: 2008BDC: 2009

ISS: 2008BDC: 2011

ISS: 2009BDC: 2010

ISS: 2009BDC: 2010

plannedfor 2011/2012

ISS: 2010BDC: 2011

Sodium intake

experiment days

0

1000

2000

3000

4000

5000

6000

Sodi

um(m

g/d) Low salt

High salt

0

10

20

30

40

50

60

70

80

90

100

ISS low ISS high BDC low BDC high

Sodium balance

More positive sodium balancein space than on earth

Sodi

um(m

mol

/d)

Body weightAstro 1

body

wei

ght (

kg)

0

74

75

76

77

78

79

80

81

82

ISS low ISS high BDC low BDC high

Bod

dy w

eigh

t (kg

)

0

85

86

87

88

89

90

91

92

body

wei

ght (

kg)

0

64

65

66

67

68

69

70

71

72

73

74

75

76

ISS low ISS high BDC low BDC high

subject 2subject 1

subject 3

sodium retention seems to beaccompanied by fluid retention

Water balance to be done

+ 0.8 kg

+ 0.5 kg

+ 0.4 kg

+ 1.25 kg

+ 1.57 kg

+ 1.25 kg

ISS low ISS high BDC low BDC high

0

5

10

15

20

ISS low ISS high BDC low BDC high

0

20

40

60

80

100

120

140

160

180

ISS low ISS high BDC low BDC high

Bone formationbAP (µg/l) PINP (µg/l)

No effect on bone formation with respect to salt intake

Calcium excretion tended to be slightly higher, different reactions regarding bone resorption marker

Conclusion

First scientific ResultsCompletion of this study, with a full complement of subjects, is mandatory to investigate the effects of salt on bone metabolism of astronauts.Sodium retention with or without fluid retention demands further analyses

Standardisation on ISSImplementation in space is more difficult than on earth (technical issues, communication)Mandatory to decrease intra-and inter variation in studies with a small number of test subjects

SOLO Benefits: Importance for space and earth

SOLO will provide information how high salt intake affects thebone turnover in general.

SOLO results will help the nutritional support teams to optimize thefood for crewmembers on long-term missions.

SOLO helps to investigate the influence of a lowmechanical impact and high salt intake on bonemetabolism.

The research will also benefit everybody withlow mechanical loads and high salt intake onearth to prevent osteoporosis.

Thanks for your attention