EFFECTS OF LONG-TERM RESTRAINT ON BODY-TEMPERATURE, BODY-WEIGHT AND PACKED CELL-VOLUME IN MICE

Long-term restraint of mice was required for low dose-rate gamma-irrad iation of the snout in studies on radiation-induced oral mucositis. To test for physiological changes, body temperature, body weight, and pa cked blood cell volume (haematocrit) were assessed during restraint in polystyrene tubes without anaesthesis for up to 6 hours. Body tempera ture decreased significantly (p < 0.01) by 2-3 degrees C during the in itial 5 to 15 minutes of restraint to reach a plateau at 35-36 degrees C. The shape of the temperature curve suggests an initial stress reac tion followed by an adaptive response. Body weight decreased in a near linear manner at a rate of 0.7 to 0.8% (0.15-0.20 g) per hour. The pa cked blood cell volume increased by 3-4% during the first 90 minutes o f restraint and subsequently remained constant at about 50%, indicatin g initial water loss from the intravascular space, which then is compe nsated by a shift of fluid from the extravascular into the intravascul ar compartment. Long-term fixation of mice in plastic tubes appears to be a feasible and suitable method to be used without anaesthesia for protracted experimental procedures.