抄録
The functional residual capacity (FRC) and airway resistance (Raw) of the rat were measured, using a newly designed body plethysmograph (BPG), the inner environment of which was maintained at body temperature and was water vapor saturated. The subjects were anesthetized and tracheally intubated male Wistar rats (n = 15). After measuring the FRC and Raw, the effects of inhaled methacholine (Mch, 0–8 mg/ml) on Raw were analyzed. The determined FRC was 5.37 ± 0.22 ml (mean ± SE). An almost linear relationship between box pressure and respiratory flow was obtained when the difference between box-gas temperature and the rectal temperature of the rat was less than 1.0°C. The Raw at FRC was 0.230 ± 0.017 cmH2O/ml/s. It increased proportionally with increases in the Mch concentration. When the dynamic changes in Raw were analyzed, the Raw was found to progressively increase during expiration; this increase continued throughout inspiration. Thus in the rat, Raw is not simply a function of changes in lung volume. In conclusion, the humidity- and temperature-adjusted BPG provided an absolute and possibly dynamic value of Raw.
