William E. Hinds

Effects of 14 days of spaceflight and nine days of recovery on cell body size and succinate dehydrogenase activity of rat dorsal root ganglion neurons

The cross-sectional areas and succinate dehydrogenase activities of L5 dorsal root ganglion neurons in rats were determined after 14 days of spaceflight and after nine days of recovery. The mean and distribution of the cross-sectional areas were similar to age-matched, ground-based controls for both the spaceflight and for the spaceflight plus recovery groups. The mean succinate dehydrogenase activity was significantly lower in spaceflight compared to aged-matched control rats, whereas the mean succinate dehydrogenase activity was similar in age-matched control and spaceflight plus recovery rats. The mean succinate dehydrogenase activity of neurons with cross-sectional areas between 1000 and 2000 microns2 was lower (between 7 and 10%) in both the spaceflight and the spaceflight plus recovery groups compared to the appropriate control groups. The reduction in the oxidative capacity of a subpopulation of sensory neurons having relatively large cross-sectional areas immediately following spaceflight and the sustained depression for nine days after returning to 1 g suggest that the 0 g environment induced significant alterations in proprioceptive function.

Influence of Spaceflight on Succinate Dehydrogenase Activity and Soma Size of Rat Ventral Horn Neurons

Succinate dehydrogenase (SDH) activities and soma cross-sectional areas (CSA) of neurons in the dorsolateral region of the ventral horn at the L5 segmental level of the spinal cord in the rat were determined after 14 days of spaceflight and after 9 days of recovery on earth. The results were compared to those in age-matched ground-based control rats. Spinal cords were quick-frozen, and the SDH activity and CSA of a sample of neurons with a visible nucleus were determined using a digitizer and a computer-assisted image analysis system. An inverse relationship between CSA and SDH activity of neurons was observed in all groups of rats. No change in mean CSA or mean SDH activity or in the size distribution of neurons was observed following spaceflight or recovery. However, there was a selective decrease in the SDH activity of neurons with soma CSA between 500 and 800 microns2 in the flight rats, and this effect persisted for at least 9 days following return to 1 g. It remains to be determined whether the selected population of motoneurons or the specific motor pools affected by spaceflight may be restricted to specific muscles.

Responses of brown-adipose-tissue activity in the rat to 14 days of spaceflight

Abstract The current study was undertaken to investigate the effects of 14 days of spaceflight (SLS-2) on the function of brown adipose tissue (BAT) in male rats. The spaceflight did not seem to have any significant effect on BAT mass or its components (total protein, DNA, RNA, and triglyceride) in the animals ( n = 13). As compared with synchronous controls ( n = 8), the expression of uncoupling protein (UCP) mRNA in BAT of flight rats was enhanced considerably ( P g and came to the same degree 9 days later. Both UCP antigen and guanosine 5′-diphosphate (GDP)-binding values in the mitochondria recovered from BAT of flight rats increased three to four times over those of control rats 9 days after flight, being highly suggestive of an increase in the thermogenic activity of BAT, but not 6 h after flight. These data suggest that spaceflight itself may not have great influence on the function of BAT. Collectively the results suggest that samples, especially BAT, should be obtained in flight as well as after in order to avoid the influences of entry to space, and reentry and readaptation to 1 · g .

Development of Experiment Kits for Processing Biological Samples In-Flight on SLS-2

The design of the hematology experiment kits for SLS-2 has resulted in a modular, flexible configuration which maximizes crew efficiency and minimizes error and confusion when dealing with over 1200 different components over the course of the mission. The kit layouts proved to be very easy to use and their packaging design provided for positive, secure containment of the many small components. The secondary Zero(Tm) box enclosure also provided an effective means for transport of the kits within the Spacelab and for grouping individual kits by flight day usage. The kits are readily adaptable to use on future flights by simply replacing the inner components as required and changing the labelling scheme to match new mission requirements.