Study of the Digestive Transportation Function of the Small Intestine

Metabolism and nutrition

Rattus norvegicus (Sprague-Dawley rat)
Flight: 10 Male

Basal: 5, Vivarium: 10

Ambient Temperature Recorder, Animal Enclosure Module

Previous experiments have revealed an increase in the acidic-peptic potential of the stomach and a decline of the functional capability of the pancreas. This experiment was to conduct a morphological and biochemical investigation of changes in the mucous membrane of the small intestine after space flight.

The duodenum, jejunum, and ileum sections of the small intestine were removed from flight and control animals, and the mucosa was examined with an electron microscope. Enzymes involved in cavity and membrane digestion (carbohydrases, peptidases, monoglyceride lipase, alkaline phosphatase) were investigated biochemically.

The investigation of the functional status of the small intestine revealed complex changes of enzyme activities. In the system of protein membrane hydrolysis, there was a shift of proximodistal gradient dipeptidase activity, indicating the compensatory nature of the changes. Analysis of processes of lipid digestion revealed a number of alterations in digestive patterns manifested as a significant decrease of nonglyceridelipase activity and an increase of alkaline phosphatase activity in the proximal segment of the small intestine. These changes also reflect the compensatory and adaptational nature of the alterations. In the carbohydrase enzymatic change, no significant alterations were found. Changes of digestive/transport hydrolysis of proteins, fats, and carbohydrates were reversible and functional in nature. The adaptive nature of the rearrangements of membrane digestion is demonstrated by a self-regulatory activity of the digestive system in the distribution of enzyme activities.

Smirnov, K.V. et al.: Study of the Digestion-Transport Conveyor in the Small Intestine. Spacelab Life Sciences-1 Final Report, NASA TM-4706, Aug 1995, p. 33.