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Increased Renal Solute Excretion in Rats Following Space FlightFollowing space flight a diuresis, due to an increase in free water clearance, has been suggested in humans. To assess the effects of space flight on renal function, rats were flown in space for 14 days. Rats were divided into three groups; vivarium controls (V;n=6; housed 2/shoe box cage), flight controls (FC;n=6; group housed in a flight cage), and flight animals (F;n=6). Upon landing all animals were placed into individual metabolic cages. Urine was collected daily for 7 days and every other day for 14 days. Urine output was increased (p less than 0.05; ANOVA) following flight for 3 days. On postflight day 1, flow rates were, V=6.8 plus or minus 0.9, FC=8.711.8 and F=16.6 plus or minus 2.7 microliter/min. Excretion rates of Na+ and K+ were increased, resulting in an increased osmotic excretion rate (V=7.9 plus or minus 0.9, FC=6.1 plus or minus 0.7 and F=13.5 plus or minus 0.7 uOsm/min). Creatinine excretion rate was increased over the first two postflight days. In the absence of changes in plasma creatinine, Na+, or K+ (samples obtained immediately post flight from similar rats compared to Day 14), GFR was increased following space flight. The increased excretion of solute was thus the result of increased delivery and decreased reabsorption. Osmotic clearance was increased (V=28, FC=27 and F=51 microliter/min), while free water clearance was decreased post flight (V=-21,FC=-18 and F=-34 microliter/min). In rats, the postflight diuresis is the result of an increase in solute (osmotic) excretion with an accompanying reduction in free water clearance.
Document ID
20020024705
Acquisition Source
Ames Research Center
Document Type
Preprint (Draft being sent to journal)
Authors
Wade, Charles E.
(NASA Ames Research Center Moffett Field, CA United States)
Moore, A. L.
(NASA Ames Research Center Moffett Field, CA United States)
Morey-Holton, E.
(NASA Ames Research Center Moffett Field, CA United States)
Date Acquired
August 20, 2013
Publication Date
January 1, 1995
Subject Category
Life Sciences (General)
Meeting Information
Meeting: Experimental Biology 1995
Location: Atlanta, GA
Country: United States
Start Date: April 9, 1995
End Date: April 13, 1995
Funding Number(s)
PROJECT: RTOP 199-40-12-01
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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