Acid-Base Metabolism, Bone Metabolism, Circulation System, Electrolyte Metabolism, Energy Metabolism
Conditions
Keywords
bone metabolism, salt intake, acid base balance, bed rest
Brief summary
The Salty Life 7 study aimed to examine the effect of a high salt (sodium chloride, NaCl) intake on different forms of sodium retention, acid-base balance and bone metabolism and other influenced physiological systems. Because of the fact that astronauts are a vulnerable group in this context, they were of special interest. Astronauts have a high salt intake, probably because of a reduced sense of taste, as well as an increased bone resorption resulting from the lowered mechanical load in space. In which forms sodium could be retained even without fluid retention (osmotically inactive)- contrary to the argumentation of physiological text books - and if the acid-base balance is connected to sodium chloride induced bone loss is examined in a stationary bed rest study with 8 healthy, young, male test subjects. The study consisting of 2 x 21 days is carried out at the German Aerospace Center (DLR). After an adaptation period of 4 days, test subjects are immobilised in 6° head-down tilt bed rest (simulation model for some physiological changes in space) for 14 days during which they received a high (7.7 mmol NaCl/kgBW/d) and a low salt (0.7 mmol NaCl/kgBW/d) intake in cross-over design. The form of sodium retention is investigated by the calculation of daily metabolic sodium-, water- and potassium balances and by changes in body weight. The measurements of bone formation (bAP, PINP, Osteocalcin) markers as well as bone resorption markers (CTX, NTX) supply insight into the influences of a high salt intake on bone metabolism. Blood gas analysis and ph values of 24-h urine are used to gather information about accompanying changes in the acid-base balance. Further physiological systems like energy metabolism and circulation system are also under investigation.
Interventions
OTHERDietary salt intake
Sponsors
Charite University, Berlin, Germany
University of Erlangen-Nürnberg
University Hospital Tuebingen
DLR German Aerospace Center
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
NONE
Eligibility
Sex/Gender
MALE
Age
20 Years to 35 Years
Healthy volunteers
Yes
Inclusion criteria
* Male * Age: 20-35 years * Weight: 65±85kg * Height:180±10cm. * Successfully completed medical & psychological screening
Exclusion criteria
* Drugs- and alcohol abuse * Hyperlipidemia * Obesity * Renal diseases * Participant of another study in the same time frame and 3 months before starting the study * Blood donation within the last three months before starting the study * Risk for thrombosis * Smoking * Diabetes * Rheumatism * Bone Fracture
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| To determine the effect of salt intake on bone metabolism in bed rest | after 14 days of high and low salt intake |
Secondary
| Measure | Time frame |
|---|---|
| To determine the effect of salt intake on acid base metabolism in bed rest | after 14 days of high and low salt intake |
| To determine the effect of salt intake on electrolyte metabolism in bed rest | after 14 days of high and low salt intake |
| To determine the effect of salt intake on the circulation system in bed rest | after 14 days of high and low salt intake |
| To determine the effect of salt intake on energy metabolism in bed rest | after 14 days of high and low salt intake |
Countries
Germany
Outcome results
None listed