Abstract
We developed the monitor the daily rhythm of respiration pattern by whole body plethysmography(WBP) using ovalbumin (OVA)-induced asthma model mouse. There are small difference of tidal volume, minute volume/body weight and respiratory frequency, but the Tienh (Ti/Te x Pe/Pi; Te/Ti,Time inspiration /Time expiration; Pe/Pi, Pressure increase by expiration/Pressure decrease by inspiration (to averaged P line) showed the circadian pattern in the asthma model mouse but not in the normal mouse. Thus, Tienh is good index for lung resistance and high Tienh represents inspiratory obstruction in asthma model mouse. A value of Tienh was higher during daytime (ZT4-7) and lower in the night time (ZT16-19). It is well known that smoking of tobacco worsens the asthmatic symptom. Therefore we asked whether smoking of tobacco affects the Tienh of respiration of the asthma model mouse. We prepared the three different type of tobacco depending on the content of nicotine and tar. Tobacco smoking elevated the value of Tienh depending on content of nicotine and tar both in normal and asthma model mice. Further experiments are required to show the effect of chronic exposure of tobacco smoking on Tienh value. The present results suggest that tobacco smoking worsens the respiratory response in the daytime (night time for humans), because respiration deficit may show circadian pattern. [J Physiol Sci. 2008;58 Suppl:S95]
