Functional residual capacity and airway resistance of the rat measured with a heat- and temperature-adjusted body plethysmograph.
The functional residual capacity (FRC) and airway resistance (R(aw)) 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 R(aw), we analyzed the effects of inhaled methacholine (Mch, 0-8 mg/ml) on R(aw).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 degrees C. The R(aw) at FRC was 0.230 +/- 0.017 cm H(2)O/ml/s. It increased proportionally with increases in the Mch concentration. When the dynamic changes in R(aw) were analyzed, the R(aw) was found to progressively increase during expiration; this increase continued throughout inspiration. Thus in the rat, R(aw) 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 R(aw).
Tajiri
Sakurako
S
Department of Medicine, Tokai University School of Medicine, Bohseidai, Isehara, Kanagawa, 259-1193 Japan.
Kondo
Tetsuri
T
Yamabayashi
Hajime
H
D000280:Administration, Inhalation; D000403:Airway Resistance / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001831:Body Temperature / Q000502:physiology*; D016084:Bronchoconstriction / Q000187:drug effects / Q000502:physiology; D016085:Bronchoconstrictor Agents / Q000008:administration & dosage / Q000494:pharmacology; D005652:Functional Residual Capacity / Q000502:physiology; D006358:Hot Temperature; D006813:Humidity; D008168:Lung / Q000502:physiology*; D008297:Male; D016210:Methacholine Chloride / Q000008:administration & dosage / Q000494:pharmacology; D010993:Plethysmography, Whole Body / Q000379:methods* / Q000662:veterinary; D051381:Rats; D017208:Rats, Wistar
D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride