SOLO SOdium LOad in microgravity

Transcription

1 SOLO SOdium LOad in microgravity Standardized Study Conditions on the ISS and on Earth Dr. Petra Frings-Meuthen DLR, Institute of Aerospace Medicine

2 Bed rest studies according to ESA standardization plan ISS experiments Study management Study protocol Volunteer selection Volunteer rules (Para) Medical Care Nutrition Biological samples Data management

3 SOLO n = 6-8, COLUMBUS Petra Frings-Meuthen 1, Martina Heer 2 & Scott Smith 3 1 DLR, Institut für Luft- und Raumfahrtmedizin, Köln 2 Universität Bonn, Profil Institute for Clinical Research, Neuss 3 NASA Johnson Space Center, Houston, USA ESA: ELIPS ILSRA day 1 day 5 day 1 day 5 Common High salt intake + controlled diet Low salt intake + controlled diet 24-h urine collection blood draw blood gas analysis body weight measurement 2 x 5 days inflight 2 x 5 days postflight (R+6-12 months) baseline data collection (BDC)

4 Sodium retention ECV microgravity very high salt sodium excretion ECV= Extracellular volume Sodium retention without fluid retention Drummer et al. EJCI 2000; Heer et al AJP 2000

5 Hypothesis 1 Higher salt intake in microgravity leads to sodium retention without fluid retention Sodium balance (intake, excretion) Water balance, body weight

6 High salt intake exacerbates immobilisation induced bone loss accompanied by changes in the acid-base and electrolyte system (DLR Salty Life 7 study, 2005) HDTBR high vs low salt urinary CTX-excretion (µg/d) meq NaCl/kgBW/d 7.7 meq NaCl/kgBW/d Bed rest period 47% p < ANOVA treat study days Frings-Meuthen et al. J Appl Physiol (in press)

7 Hypothesis 2 Higher salt intake exacerbates microgravity induced increased calcium excretion & bone resorption calcium excretion bone resorption marker bone formation marker Standardisation: Nutrient intake Environmental conditions Physical activity Sampling & Analysing methods

8 High Salt Low Salt Energy (kcal) Protein (g) Fat (g) CH (g) Na (mg) K (mg) H2O (g) Breakfast Apple Cider 113 0, Cocoa 198 3, Sausage Pattie 118 9, Split Top Roll Grits with Butter 116 2, Lunch Lemonade Hot & Sour Soup 65 3, Beef Fajitas , Tomatoes & Artichokes 74 2, Pears 96 0, Dinner Peach Apricot Drink Chicken w/ Peanut Sauce , Potatoes au Gratin 147 4, Creamed Spinach 65 3, Cherry Blueberry Cobbler 308 2, Snack Apple Cider 113 0, Blueberry Raspberry Yoghurt 140 4, Almonds SUM , Energy (kcal) Protein (g) Fat (g) CH (g) Na (mg) K (mg) H2O (g) Breakfast Chocolate Breakfast Drink Granola w/blueberries 246 7, Berry Medley 97 1, Waffles 200 2, Orange Drink Lunch Apple Cider 113 0, Sweet & Sour Chicken , Potato Medley 101 1, Blueberry Raspberry Yoghurt 140 4, Dinner Peach Apricot Drink Chicken Pineapple Salad , Barbecued Beef Brisket , Green Bean & Potatoes 48 1, Cherry Blueberry Cobbler 308 2, Snack Lemonade Macadamia Nuts 312 4, Cocoa 198 3, SUM ,

9 SOLO Hardware: standardized procedures Measuring urine volume via scaling Urine collection Blood draw Body mass measurement Blood gas analysis

10 Experiment Status ISS: 2008 BDC: 2011 ISS: 2008 BDC: 2009 ISS: 2010 BDC: 2011 planned for 2011/2012 ISS: 2009 BDC: 2010 ISS: 2009 BDC: 2010

11 Sodium intake Sodium balance 6000 Sodium (mg/d) Low salt High salt Sodium (mmol/d) experiment days 0 ISS low ISS high BDC low BDC high More positive sodium balance in space than on earth

12 82 81 Astro 1 subject kg Body weight subject kg body weight (kg) kg Boddy weight (kg) kg body weight (kg) ISS low ISS high BDC low BDC high subject kg kg 85 0 ISS low ISS high BDC low BDC high sodium retention seems to be accompanied by fluid retention Water balance to be done ISS low ISS high BDC low BDC high

13 Bone formation 20 bap (µg/l) 180 PINP (µg/l) ISS low ISS high BDC low BDC high ISS low ISS high BDC low BDC high No effect on bone formation with respect to salt intake Calcium excretion tended to be slightly higher, different reactions regarding bone resorption marker

14 Conclusion First scientific Results Completion 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 ISS Implementation 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

15 SOLO Benefits: Importance for space and earth SOLO will provide information how high salt intake affects the bone turnover in general. SOLO results will help the nutritional support teams to optimize the food for crewmembers on long-term missions. SOLO helps to investigate the influence of a low mechanical impact and high salt intake on bone metabolism. The research will also benefit everybody with low mechanical loads and high salt intake on earth to prevent osteoporosis.

16 Thanks for your attention