A comparative analysis of the excretory and incretory activity of the stomach and pancreas in astronauts soon after completion of space flights of various durations was performed. An increase in the fasting activity of gastric and pancreatic enzymes and hormones (insulin and C-peptide) in blood, reflecting the increased excretory and incretory activity of organs of the gastroduodenal region developing in microgravity, was demonstrated. The absence of subjects infected with Helicobacter pylori in the space flight crew excluded the involvement of this microorganism in the mechanism underlying the increase in the gastric secretory activity. The absence of correlation between the increase in the secretory activity of organs of the gastroduodenal region and the duration of the space flight allowed us to rule out the hypokinetic mechanism, which is associated with the duration of exposure to microgravity. It was concluded that the main mechanism underlying the changes in the functional state of the digestive system in space flight may be determined by the rearrangement of the venous hemodynamics of organs of the abdominal cavity, unrelated to the duration of exposure to microgravity. It was shown that, after completion of space flights and in ground-based experiments simulating the hemodynamic rearrangement occurring in microgravity, the increase in the basal excretory activity of gastroduodenal organs was not caused by gastrin secretion and occurred simultaneously with an increase in the secretion of insulin, which is considered as a putative hormonal component of the hemodynamic mechanism.
Research Containing: Space Flight
The present suite of advanced space plant cultivation facilities require a significant level of resources to launch and maintain in flight. The facilities are designed to accommodate a broad size range of plant species and are, therefore, not configured to support the specific growth requirements of small plant species such as Arabidopsis thaliana at maximum efficiency with respect to mass and power. The facilities are equally not configured to support automated plant harvesting or tissue processing procedures, but rely on crew intervention and time. The recent reorganization of both spaceflight opportunities and allocation of limited in-flight resources demand that experiments be conducted with optimal efficiency. The emergence of A. thaliana as a dominant space flight model organism utilized in research on vegetative and reproductive phase biology provides strong justification for the establishment of a dedicated cultivation system for this species. This paper presents work on the design of a small plant cultivation facility directed at supporting research on the vegetative growth phase of A. thaliana . The design of the facility is based on the use of existing space flight hardware, and configured to support the fully automated germination of seed, cultivation of plants, and final termination of plant growth by chemical fixation and preservation of plant tissue.
Constraints in both launch opportunities and the availability of in-flight resources for Shuttle and Space Station life science habitat facilities has presented a compelling impetus to improve the operational flexibility, efficiency and miniaturization of many of these systems. Such advances would not only invigorate the level of research being conducted in low Earth orbit but also present the opportunity to expand life science studies to outer space and planetary bodies. Work has been directed towards the development of a miniature plant cultivation module (PCM) capable of supporting the automated and controlled growth and spectral monitoring of small plant species such as Arabidopsis thaliana. This paper will present data on the operational performance and efficiency of the cultivation module, and the extent to which such a system may be used to support plant growth studies in low Earth orbit and beyond.