A total of twelve large rats (400 g) and twelve small rats (200 g), all specific pathogen free, were flown in the RAHF for seven days. About three weeks before flight, biotelemetry transmitters for measurement of EKG, deep-body temperature and heart rate were implanted into seventeen large rats, five of which were selected for flight. Three to five days after surgery, implanted rats were placed in flight-type cages and the signals from their transmitters monitored to establish preflight diurnal rhythms. About thirteen days before launch, the remaining animals were also placed in flight-type cages where the rats could learn to use the flight feeders and lixits. Body, food, and water weights were observed preflight. The 24 flight animals were inspected and weighed at recovery at the landing site in California, then flown to Kennedy Space Center for further inspection, microbiological sampling, and sacrifice. Organs and tissues were weighed and preserved for biosample distribution for further analyses.

Results:

The RAHF functioned well in providing an adequate environment and nutrition for the animals. When recovered, rats had an extensive coating of dried urine and food powder on their coats but were otherwise healthy and in good condition. A variable air flow rate in the cage modules may have prevented some of the urine, feces and food powder from being deposited in the waste collection trays, which resulted in some of the particulate matter escaping from the RAHF during feeder and waste tray change-outs. Rats were strikingly calm when handled and did not resist oral swabs or fecal collection. An unexplained disparity was seen in the growth rates of flight rats with telemetry implants as compared to the implanted ground controls. Elevated blood glucose concentrations in both large and small rats probably reflect reentry stress, analogous to the responses shown by astronauts postflight. Other increased blood chemical responses shown by small flight rats included urea nitrogen, cholesterol, potassium and glutamic-pyruvic transaminase, and may indicate muscle wasting or responses of growing rats to microgravity.