Airway response to induced muscular contraction in spontaneously breathing rabbits

详细信息    查看全文

• 作者：Franç ; ois Marchal ; Bruno Demoulin ; Cyril Schweitzer ; Anne Laure Leblanc ; Noë ; lle Bertin
• 关键词：Exercise ; Bronchodilation ; Bronchomotor tone ; Methacholine ; Airway calibre ; Breathing pattern ; Augmented breath ; Airway wall hysteresis
• 刊名：Respiratory Physiology & Neurobiology
• 出版年：2008
• 出版时间：1 February 2008
• 年：2008
• 卷：160
• 期：2
• 页码：224-231
• 全文大小：212 K

文摘

The airways are thought to dilate during exercise in humans but the time course and mechanisms of the response are not fully described. The aim of the study was to document changes in airway calibre during electrically induced muscular contractions (MC) in spontaneously breathing rabbits. Experiments were also performed after induced bronchoconstriction to assess the effect of change in breathing pattern on airway calibre during MC. Respiratory resistance (R_RS) was measured in 12 rabbits using the forced oscillation technique at 20 Hz before, during and after 30 s MC in control conditions and after methacholine induced bronchoconstriction (Mch). MC was associated with significant decrease in R_RS both at control and Mch. The MC induced increase in V_E occurred with significant albeit small change in mean tidal volume (V_T) at Mch but not control. An augmented breath (AB) occurred in 29/35 MCs and was usually associated with an abrupt drop in R_RS. The decrease in R_RS induced by AB was significantly larger at Mch compared with control. Passively inflating the lung after MC induced significantly larger decrease in R_RS than AB during MC. The data indicate bronchodilation by MC in spontaneously breathing rabbits. The mechanisms appear to include AB dependent airway wall stretching as well as removal of cholinergic input to the airway smooth muscle.