抄録
Last year we described the flow-volume curve (F-V curve) in rats. In that study rats were orally intubated using 14G (OD 1.75mm) cannulas. The F-V curve revealed a long ascending limb similar to that seen in human with extrathoracic upper airway obstruction. In the current study we examined the effect of tracheal cannula caliber on the F-V curve. The maximum cannula size used for Wistar or Norway Brown strain rats of 8-9 week of age was 13G (OD 1.95mm) for oral intubation and 14G (OD 1.95mm) for tracheostomy. The use of 12G or 13G cannulas respectively shortened the ascending limb of the F-V curve. The curve consisted of 3 phases: a steep ascending, a mild descending and a steep descending phase. Expiratory flow in the ascending limb increased along with increase in thoracic pressure while the mild descending limb was unaffected. When airways were constricted by inhaled methacholine the mild descending phase was shortened and vital capacity decreased, although the other phases were not affected. These findings suggest that large airway caliber is the crucial determinant of F-V curve in rats. To analyze F-V curves in rats maximal cannula size should be used. [J Physiol Sci. 2008;58 Suppl:S117]
